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11-1-1991

Hydroboration-oxidation of styrene, 2,3dihydrofuran and quadricyclene dimethylesterpromoted by Wilkinson's catalystPingyun Feng

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Recommended CitationFeng, Pingyun, "Hydroboration-oxidation of styrene, 2,3 dihydrofuran and quadricyclene dimethylester promoted by Wilkinson'scatalyst" (1991). Thesis. Rochester Institute of Technology. Accessed from

HYDROBORATION-OXIDATION OF STYRENE, 2,3-DIHYDROFURAN

AND QUADRICYCLENE DIMETHYLESTER PROMOTED

BY WILKINSON'S CATALYST

PINGYUN FENG

NOVEMBER,1991

THESIS

SUBMITTED IN PARTIAL FULFILLMENT OF THE

REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE

APPROVED:

Terence C. MorrillProject Adviser

Gerald A. TakaerDepartment Head

Library

Rochester Institute of Technology

Rochester, New York 14623

Department of Chemistry

Title of thesis

Hydroboration-oxidation of Styrene, 2,3-Dihydrofuran and Quadricyclene

Dimethylester Promoted by Wilkinson's Catalyst

I Pingyun Feng hereby grant permission to the Wallace Memorial Library of RIT to

reproduce my thesis in whole or in part. Any reproduction will not be for conunercial use

or profit.

Date: Nov. 25 , 1991

Pingyun Feng

Table of Contents

Acknowledgments

Abstract

Introduction 1

Mechanism of Hydroboration-oxidation 2

Catecholborane 4

Wilkinson's Catalyst 7

Mechanism of Hydrogenation with Wilkinson's Catalyst 9

Hydroboration of Styrene 10

Hydroboration of Heterocyclic Olefins 12

Hydroboration of a Cyclopropane Ring in the Quadricyclene System 15

Experimental 19

Hydroboration-oxidation of Styrene 21

Hydroboration-oxidation 2,3-Dihydrofuran 31

Preparation of Quadricyclene Dimethylester 34

Preparation of Quadricyclene Dicarboxylic acid 39

Results and Discussion 42

Hydroboration of Styrene with BH3THF 42

Hydroboration of Styrene with Catecholborane 44

Hydroboration of Styrene Promoted by Wilkinson's Catalyst 44

Mechanism of Rhodium Catalyzed Hydroboration of Olefins 48

Hydroboration of 2,3-Dihydrofuran Promoted byWilkinson's Catalyst.... 54

Hydroboration of Cyclopropane Ring in Quadricyclene System 57

Spectra

300MHz !HNMR ofNorbornadiene Dimethylester in CD3COCD3 6 1

200MHz XH NMR ofNorbornadiene Diacid in CD3COCD3 62

200MHz lH NMR ofQuadricyclene Diacid in DMSO 63

GC - Mass Spectrum of the Reaction of Styrene and BH3THF

withoutWilkinson's Catalyst 64

GC - Mass Spectrum of the Reaction of Styrene and BH3THF

withWilkinson's Catalyst 65

GC - Mass Spectrum of the Reaction of Styrene and Catecholborane

withoutWilkinson's Catalyst 66

GC - Mass Spectrum of the Reaction of Styrene and Catecholborane

withWilkinson's Catalyst (reaction time 0.5 hr.) 67

GC - Mass Spectrum of the Reaction of 2,3-Dihydrofuran and BH3THF

withoutWilkinson's Catalyst 68

GC - Mass Spectrum of the Reaction of 2,3-Dihydrofuran and BH3THF

withWilkinson's Catalyst 69

Capillary GC Spectrum ofAuthentic a - Phenylethanol Sample 70

Capillary GC Spectrum ofAuthentic P - Phenylethanol Sample 7 1

Capillary GC Spectrum of the Reaction of Styrene and Catacholborane

withWilkinson's Catalyst (reaction time 1 hr. ) 72

Capillary GC Spectrum of the Reaction of Styrene and Catacholborane

withWilkinson's Catalyst (reaction time 0.5 hr. ) 73

Introduction

The remarkable facile addition of diborane in ether solvents to olefins1,dienes2

andacetylenes3

at room temperature was discovered in 1956 by Herbert C.Brown.4

The reaction, hydroboration, makes readily available awide variety of organoboranes

which are proving to be exceedingly useful in organic synthesis. A wide variety of

olefins, amines, ketones and particularly, alcohols of desired structure and

stereochemistry have been prepared by the hydroboration - oxidationsequence.5

Pretiminary observations indicated that the addition to an unsymmetrical olefin proceeds

to place the boron atom on the less substituted of the two carbon atoms forming the

double bond6. Since the organoborane is readily converted to the corresponding alcohol

by oxidation with alkaline hydrogen peroxide, hydroboration provides a simple

convenient synthetic route for the anti-Markovinikoff hydration of olefins.

Recently, several groups (RIT, Harvard, Rice, Germany) have applied

transition metal catalysis to hydroboration resulting in rate enhancements for less

reactive borane reagents as well as complementary or improvedregio- and

stereochemistry. The possibility has been raised that transition metal catalysis might

significantly extend the utility of the hydroborationreaction.7

1Brown, H. C.,and Zweifel, G., /. Org. Chem., I960, 82, 4708.

2Brown, H. C.,and Zweifel, G., /. Org. Chem., 1959, 81, 5832.

3 Brown, H. C.,and Zweifel, G., /. Org. Chem., 1959, 81, 1512

4 PurdueUniversity,Nobel Prize Laureate 1979.

5 Ruffing, C. J., Aldrichimica Acta, 1989, 22, 3, 80

6 Brown, H. C.,and Zweifel, G., J. Org. Chem., 1960, 82, 4708.

7 Evans, D. A. Fu, G. C. ,and Hoveyda, A. H. ,

/. Am. Chem. Soc. 1988, 770, 6917.

Borane, BH3, is an avid electron pair acceptor because only a sextet of valence

electrons is present at boron in the monomelic molecule. The pure neat material exists

as adimer.8 Diborane can be generated in situ from sodium borohydride and boron

trifluoride. In aprotic solvents which act as electron pair donors such as ethers, tertiary

amines, and sulfides, tetrahydrofuran,we have known that diborane forms stable Lewis

acid-Lewis base complexes.

2R20+

B2H6 -2BH3 .

'

1 2R2Q BH3

Solutions of BH3-THF complex in tetrahydrofuran are commercially available.

An alternative commercially available borane reagent is the borane-dimethyl sulfide

complex. Both hydroboration reagents BH3THF and BH3-SMe2 react rapidly with

unsaturated carbon- carbon bonds and do not require metal or other catalysis.

Mechanism of Hvdroboration-Oxidation

Hydroboration is not only stereospecific ( syn addition ) but also regioselective;

steric and electronic factors control the regioselectivity: the boron atom binds to the less

hindered ( less substituted ) carbon, and the hydrogen atom binds to the more

substituted carbon.

Because the k bond in a carbon - carbon double bond is electron rich and

borane is electron poor, it is reasonable to formulate an initial Lewis acid base

complex, requiring the participation of the empty p orbital on BH3, as in the borane -

8 Carey, F. A. and Sunderrg, R. J., Advanced Organic Chemistry, Plenum Press, New York 1983,

167.

ether complex. Subsequently, one of the hydrogens is transferred by means of a four

centered transition state to one of the alkene carbons. All three B-H bonds are reactive

in the same way and therefore trialkylboranes are formed. Then the trialkylboranes are

oxidized with basic aqueous hydrogen peroxide; the highly nucleophilic and electron-

rich hydroperoxide ion attacks the electron - poor boron atom. The resulting

intermediate undergoes a rearrangement in which an alkyl group migrates with its

electron pair keeping the same configuration to the neighboring oxygen, displacing a

hydroxide group in this process. Although the hydroxide ion is usually a poor leaving

group, the reactive O-O bond and the simple intermolecular nature of this reaction

allows it to leave. The initial productR2BOR undergoes further similar oxidations to a

trialkyl borate (RO)3B which is hydrolyzed by the basic aqueous medium to the alcohol

(ROH) and sodium borate.9.

This mechanism is shown below:

R

R

- NaOHI - r^-

+ :0-OH 777^R B OOH

H2U

R

-

OH-

-? R B

R

OR

HOO-HOO"

? aa*

-

OH"

- OH

9 Vollhardt,K. C, Organic Chemistry, W. H. Freeman and Company, New York, 1987, 479.

- OH-? R B

R

NaOH '- r~^.

+ :0 - OH TT ^ R B O OHH20

R

OR

R

HOO" HOO"

? a**

OH -

OH"

In addition to borane reagent, there are other hydroboration reagents which are

available such as disiamylborane, 9 - BBN, catecholborane, and chloroborane. One of

the more interesting is catecholborane (1,3,2-benzodioxaborole).

Catecholborane

Catecholborane (CB) is readily available from the reaction of catechol with

borane complex in THF10:

10 Brown, H. C. and Gupta, S. K., /. Am. Chem. Soc. 1975, 97, 5249.

OH

OC + BH: THFTHF

OH0 -

25"

C

( CB )

In catecholborane, the boron atom is part of a planar five-membered ring. It has

unique structural features and is only a mild hydroboration agent due to competing

electron donation from the adjacent oxygen in the five-membered ring. It is amuch

weakerLewis acid than the borane complex. Hydroboration with catecholborane is

usually very slow at room temperature, while at high temperature the hydroboration

proceeds at much more satisfactory rate. It hydroborates olefins at 100C.11 It reacts

with acetylenes at 70 C.12

B H

RCH=CHR'

100

RC^CR'

70'

BCH-CH2R'

Several groups have now applied transition-metal catalysis to hydroboration

resulting in rate enhancement for less reactive boron reagents, such as

1 1Brown, H. C. and Gupta, S. K., /. Am. Chem. Soc. 1971, 93, 1816.

12Brown, H. C. and Gupta, S. K., /. Am. Chem. Soc. 1972, 94, 4370.

catecholborane13. For example, without a catalyst, two above reactions require

temperature of 100C and 70C respectively; however, they can occur without

difficulty at room temperature in the presence of a catalyst. Mannig and Noth have

found that it is possible to activate the carbon-carbon double bonds of olefins so

strongly that they are preferentially hydroborated even in the presence of the much more

reactive keto group.14 For example, without a catalyst, 5-hexen-2-one reacts with

catecholborane (1) rapidly and quantitatively give2-(l-methyl-4-pentenyloxy)-l,3,2-

benzodioxaborole (2) , whereas in the presence ofWilkinson's catalyst, RhCl(PPh3)3,

the ketone (3) is preferentially formed:

OC>--wOc>- +

^Y<>

0 oa\Q-\^^

In addition toWilkinson's catalyst, the complexes [RhCl(CO){P(C6H5)3}2],

[RhCl(CO){As(C6H5)3h], and [RhCl(cod)]2 (cod= 1,5 -cyclooctadiene) are also

suitable as catalysts for hydroboration with CB, but complexes of platium, palladium,

iridium, and cobalt exhibit no or only minor catalyticeffects.14We useWilkinson's

catalyst in our experiments, the reagent that is convenient because it is stable in air and

yet exhibits high reactivity.

13 Ruffing, C. J. Aldrichimica Acta, 1989, 22, 80.

14Mannig, D. and Noth, H., Angew. Chem. Int. Ed. Engl, 1985, 24, 878.

Like the keto group, other function groups such as hydroxy-, cyano-, nitro-,

chloro-, azo-. ether, ester, and carboxylic acid groups are also not effected by

Wilkinson's catalyst under these conditions.

Wilkinson's Catalyst

Two independent reports15 appeared in 1965 that the complex

chlorotris(triphenylphosphine)rhodium(l), RhCl(PPh3)3, in organic solvents is an

active catalyst for reduction of alkynes and alkenes at ambient temperature and

atmospheric pressure. This compound has subsequently become known as Wilkinson's

catalyst. Its X-raystructure16 is shown below ( Fig. 1 ).

15 Young, J. F., Osborne, J. A., Jardine, F. H., andWilkinson, G. /. Chem. Soc. Chem.

Commun., 1965, 131; Coffey, R. S., ICI Ltd. Br. Pat., 1965, 1, 121.

16 Huheey, J. E., Inorganic Chemistry, Third edition, Harper & Row, Publishers, New York,

1983, 655.

Figure 1. X -

ray structure of Wilkinson's catalyst:

&.***!E5SS2ESS5F(*'p,'Rha*-> ' - *-*.*~*-*-.

In this structure, RhCl(PPh3)3 has 16 electrons in Rh valence shell, the dimer

or the 5-co-ordinate complex of RhOQ?Ph3)4 does not form during preparation due to

the excess of triphenylphosphine in the solution and the steric factor (large phenyl

groups). Actually, the dimer can be readily converted to RhOQ?Ph3)3 by heating with a

10 molar excess of triphenylphosphine inethanol.17

The tristriphenylphosphine halide dissociates in solution as shown:

RhCl(PPh3)3-

Ethanola**

RhCl(PPh3)2 + PPh3

17 Osborn, J. A., Jardine, F. H., Young, J. F. and Wilkinson, G., J. Chem. Soc. (A) 1966, 1711

The essential point is that RhCl(PPh3)2 has vacant coordination sites which can

be occupied either by weakly bound solvent molecules or by other ligand atoms. The

existence of vacant sites is essential to the catalytic activity ofRhClQ?Ph3)2 as we shall

see below from the mechanism.18

Mechanism of Hvdrogenation with Wilkinson's Catalyst

The mechanism of hydrogenation includes three major steps: oxidative-addition,

insertion, and reductive-elimination

Figure 2 : Mechanism of Hydrogenation with Wilkinson's Catalyst

H H

H2 \ I /H. Solvent

Ph3P !| H

(Ph3P)3RhCl

^=^\Rh/ -

\^ci</|N^ph3p aS >Ph3

Solvent ige

18e

16e

18 Pearson, J. Metallo-organic Chemistry ,AWiley - Interscience Publication 1985

- Alkane

Red.- Elimin.

H

Ph3P. |

CI/ I ^Ph3P^C =

c"

18e

Ph3P

Rh

a/ N

H H,

Insertion

Ph.P

H

C-C-H

%/iA

CI/ ^Ph.P

16e

Solvent

Ph^P(Ph3P)3RhCl

16e

16e

The mechanism of hydroboration promoted byWilkinson's catalyst is not yet

completely understood. A mechanism similar to hydrogenation has been suggested. We

will discuss this in more detail in Results and Discussion section.

Hydroboration - Oxidation of Stvrene

The hydroboration of simple terminal alkenes such as 1-butene, 1-pentene and

1-hexene with diborane in THF proceeds in a highly regioselective manner to give

predominant addition of the boron atom to the terminal carbon atom ( ~ 93 - 94 % ).

Only a minor amount of addition to give the secondary alkyl boron product is observed

( ~ 6 - 7 % )19. These results correspond to a predomination of anti-Markovnikov

I9Brown, H. C. and Zweifel, G. /. Org. Chem., 1960, 82, 4708

10

addition. The hydroboration of terminal alkenes with an alkyl substituted at the 2-

position, such as isobutylene, proceeds to give almost exclusively ( 99% ) the terminal

hydroboration products20. On the other hand, the hydroboration of another terminal

alkene, styrene, results in only 81% of the boron atom entering the terminal position,

reflecting the significant non-steric directive influence of the phenylsubstituted.21

It became of interest to investigate such directive effects in the hydroboration of

alkenes with catecholborane. In 1975 H. C. Brown and S. K. Gupta investigated such

directive effects in the hydroboration of styrene with catecholborane at 100C. The

results indicated that catecholborane is more selective than borane in placing the boron

atom preferentially at the less hindered carbonatom.21 For example, they used

1-

decene, 1-diisobutylene, norbomene and styrene for their experiments. After the

standard hydroboration with catecholborane ( 10 % excess ) at 100C, the product

organoborane was then oxidized with alkaline hydrogen peroxide. The following

results were obtained:

CH3 CH3I I

CH3(CH2)7CH=CH2CH3C- CH2- C = CH2

ICH, t t

2% 98%1% 99%

20 Brown, H. C."

Hydroboration ", W. A. Benjamin, New York, 1962

21Brown, H. C. and Gupta, S. K., /. Am. Chem. Soc. 1975 , 97, 5249.

11

99.5%

0.5%

The above results indicate that catacholborane is somewhat more

selective than borane in placing the borane in less hindered carbon atom. Even the

directive effect of the styrene changed from 80% with borane to 92% with

catacholborane.

It was of greater interest to investigate hydroboration of styrene and other

alkenes withWilkinson's catalyst. Some very interesting results have been obtained

and we will discuss them in more detail below.

Hydroboration of Heterocyclic Olefins

Heterocyclic derivatives introduce some major differences in hydroboration-

organoborane reactions. First, the heterocyclic atom plays amajor role in controlling

the direction of hydroboration of double (and triple) bonds. Secondly, the presence of a

boron atom (3- to the heteroatom can result in facile ringopening:22 For example:

22Brown, H. C. and Rangaishenvi, M. V. J. Heterocyclic Chem., 1990, 27, 13.

12

R2BH

O

/

NaOH

O

V

OH

I

.BR2

r

o

+

Na

/

O

R2BOH

/

O

I

HO-BR2

+

Na

/

Ring opening can be thought of as a elirnination from the intermediate in the

reaction below. The extent of ehmination depends upon a number of factors, such as

leaving group (X), temperature andsolvent.23

RCH= CHX

X

B-HRCHCH2X-

I

\RCH=CH2 + B-X

IfX is a good leaving group, such as CI, or OAc, the ehmination occurs

rapidly.24'25'26 Elimination is minimized for poor leaving groups, such as OR and

OAr. It was observed that such hydroboration can proceed with a remarkable

23Brown, H. C. Vara Prasad, J. V. N., and Zee, S. H., /. Org. Chem. 1985, 50, 1582.

24Brown, H. C, Unni, M. K. /. Am. Chem. Soc. 1968, 90, 2902.

25Brown, H. C, Gallivan, R. M, Jr. /. Am. Chem. Soc. 1968, 90, 2906.

26Brown, H. C, Sharp, R. L. /. Am. Chem. Soc. 1968, 90, 2915.

13

regioselectivity, placing essentially all of the boron atom at the (3 - position27,28. For

example, l-ethoxy-2-methyl-l-propene yields 88% l-ethoxy-2-methyl 2-propanol

upon hydroboration-oxidation, indicating the preference of the boron atom for a p-

carbon atom even though it is tertiary.29

CH3 CH3

I ^B-H 'NaOH, H202

rH3r=rHor:H:'* n

, ch3cch2oc2h5 L_i_i

P a

/Bx

CH3I

CH3CCH2OC2H5

OH

Although there have been individual reports on the hydroboration of

heterocyclic olefins containingoxygen,30 sulfur,31

andnitrogen32'33

,clear

understanding of the optimum conditions required for clean and efficient hydroboration

of heterocyclic olefins is still lacking.

27Pasto, D. J. and Cumbo.C. C, /. Am. Chem. Soc. 1964, 86, 4343.

28Zweifel, G., and Plamondon, J., /. Org. Chem. 1970, 35, 898.

29Brown, H. C, and Sharp, R. L., /. Am. Chem. Soc. 1968, 90, 2915.

30Still, C, Goldsmith, W. Jr., /. Org. Chem. 1970, 35, 2282.

3iKrug, R. C, Boswell, D. E. ,

/. Org. Chem. 1962, 27, 95.

32Caron-Sigaut, C, Le Men-Oliver, L., Hugel, G., Levy, J., Le Men, J. Tetrahedron 1979, 35,

957.

33 Shono, T., Matsumura, Y., Tsubata, K., Sugihara, Y., Yamane, S., Kanazawa, T., Aoki, T. /.

Am. Chem. Soc. 1982, 704, 6697.

14

So it became of interest for us to study the hydroboration of heterocyclic olefins

and hydroboration of heterocyclic olefins promoted byWilkinson's catalyst. We chose

2,3 - dihydrofuran for our study.

Hydroboration of a Cyclopropane Ring in the Quadricyclene System

Many chemical reactions of quadricyclene system have been studied.34'35'36

Hydroboration-oxidation of the cyclopropane ring of this system is a very new area.

The cleavage of cyclopropane in norcarane by neat diborane has been reported by

Rickborn andWood.37 The reaction is quite regioselective and the products were those

involving boron addition to the least-substituted carbon, and hydrogen to themost-

substituted carbon (Markovnikov addition). Some examples are given here.

34 Nikolai S. Zefirov, N. K. Sadovaya, T. N. Velikokhat'ko, L. A. Andreeva, and Terence C.

Morrill, /. Org. Chem. 1982, 8, 47.

35Stanley J. C. and Robert L. S., /. Am. Chem. Soc. 1958, 80, 1950.

36 McCulloch, A. W., Mcinnes, A. G., Smith, D. G. andWalter, J. A. Can. J. Chem. 1976, 54,

2014

37 Rickborn, B. andWood, S. E. /. Am. Chem. Soc. 1971, 93, 3940

15

1. B2H6,107;2.H202,

OH"

95%

CH2OH

OH

0 %

OH

5%

This reaction is a highly regioselsctive cleavage process with only 5% of

cyclohexanol formed due to the cleavage of the internal bond.

1.B2H6>105,1 hr

2.H202OH" OH

95% 5%

OH

We plan to use quadricyclene dimethyl ester for our study. Some chemical

properties of this system have been studied. Early work clearly describes the

16

propensity for C5 - Q; or C1 -C7 ( shown in compound 4 ) bond cleavage in this

system.38

COOH

COOH

(4)

For example, addition of bromine to this system has been reported to give (6)

and (5),

COO]

(5) (6)

38 Cristol, J., Harrington, J. K., Morrill ,T. C. and greenwald, B. E., /. Org. Chem., 1971, 36,

2773

17

The C-3 carboxylic group was shown to be endo by the ready formation of

lactone (6). Structure (5) with exo- Br at the secondary halide position appeared to be

reasonable, as it permitted the formation of (6) by a stereochemically expected inversion

process.39

Other examples such as addition of benzenesulfenyl chloride to quadricyclene

dicarboxylic acid and dimethyl ester also revealed the C5 -Q ( Ci - C7 ) bond cleavage

propensity in thissystem.40

39 Cristol, S.J., Harrington, J. K. and Singer, M. S., /. Am. Chem. Soc. 1966, 88, 1529

40 Morrill, T. C, Malasanta, S. Warren, K. M. and Greenwald, B. E., /. Org. Chem., 1975, 40,

3032

18

Experimental

Nuclearmagnetic resonance spectra were obtained using either a Bruker

FT-NMR spectrometer (200MHz ); or a G. E. QE (300MHz). Tetramethylsilane

(TMS) was used as a reference standard, and all chemical shifts were recorded in 8

units (ppm) related to TMS (8 = 0.00 ppm). Multiplicity notations are: s, singlet; d,

doublet; t, triplet.

The GC Mass Spectrometric Analyses were performed on a Hewlett Packard

5995 GC/MS with a Supeleco fused silica capillary SPB-1 non-polar column ( 30 m,

0.32 mm ID, 1.0 mm df ). Helium was used as the carrier gas.

Capillary Gas Chromatography spectra was performed on a Hewlett Packard

5890A with a 50m x 0.32mm x 0.25 (J.m HP-1 ( cross linked methyl silicone gum )

non-polar column. Helium was used as the carrier gas. Flame ionization detectorwas

used.

Melting points were determined using aMel-Temp

apparatus from Lab

Specialties Incorporation, and required no correction as per calibration by benzoic acid.

Photochemical reactions were carried out using a 1 -literPyrex photochemical

reaction vessel and a 450-Watt high pressure mercury vapor lamp QZnglehardHanovia,

Inc.) was placed in a quartz immersion well. The quartz immersion well was placed in

19

the reaction jacket. The diagram of the 1-literPyrex photochemical reaction vessel

was shown in Figure 3.

Dry nitrogen was prepared by passing reagent grade nitrogen from Linde Air

Products through Fieser's reagent ( see experiment 3 ) followd by passage through

concentrated sulfuric acid and anhydrous potassium hydroxide.

Chemicals and solvents were purchased from Aldrich Chemical Co., Sigma

Chemical Co., Fisher, and Baker.

20

Hydroboration-oxidation of Stvrene

1. Hydroboration-oxidation of Styrene with BH-yTHF

All glassware was predried in an oven at 150 overnight, assembled hot, and

allowed to cool under a stream ofdry,41 deoxygenated nitrogen42. The nitrogen gas

was purified by Fieser's solution43, NaOH, and H2SO4.

A dry three-necked 250 ml flask was equipped with a magnetic stirring bar, a

condenser, and a pressure-equalizing dropping funnel. After cooling down to room

temperature under a stream of nitrogen, the flask was charged with 2.08g ( 20mmol )

of styrene by removing the condenser and adding the styrene as quickly as possible

under a blanket of nitrogen. The system was then reflushed with nitrogen for several

minutes, and 20 ml ( 20 mmol ) ofBH3-THF ( 1.0M THF solution ) was added to the

dropping funnel with a syringe.

Hydroboration was achieved by the slow dropwise addition of the BH3-THF

solution to the flask. Following the addition, the colorless reaction mixture was stirred

at the room temperature for 1 hour. The reaction mixture was then cooled in an ice bath

and 10 ml of a 30% H2O2 solution and 10 ml of 3M NaOH solution was added to the

reaction flask. Care was taken to maintain the solution slightly alkaline ( pH ~ 8 ). The

reaction was stirred for 3 hours and the reaction temperature was allowed to reach room

temperature.

4iBrown, Herbert C. Organic Syntheses Via Boranes, AWiley-Interscience Publication, JohnWiley

& Sons, 1975

42 See experiment 2

43 See experiment 3

21

Then anhydrous ethyl ether (3 x 20) ml was used to extract the alcohol

products. The combined ether extracts were washed with a 20 ml of saturated sodium

bicarbonate solution and then 2x20 ml of distilled water; the ether layer was

subsequently separated and dried over anhydrous magnesium sulfate.

The product mixture was analyzed by GC/MS spectrometry and comparedwith

authentic sample from Aldrich.

Mass spectrum of C6H5CHOHCH3 (9) : m/z 79 (100%), m/z 107 (84%), m/z

122 (28%), m/z 43 (42%), m/z 51 (30%), m/z 27 (11%). Retention time as shown on

GC/MS spectra was: 1.674 min .

Mass spectrum of C6H5CH2CH2OH (8) : m/z 91 (100%), m/z 122 (28%),

m/z 65 (25%), m/z 31 (10%). Retention time as shown on GC/MS spectra was: 1.782

min.

l.BH3-THF, RT, lh

2.H202, NaOH

OHOH

V

(7)

80.7%

(8)

19.3%

(9)

The total yield for this reaction was 78.9%. The yieldwas determined by

weight after evaporating solvent andmultiplying by the GC percentage of products (8)

and (9); GC identification was done by using authentic (Aldrich) samples of (8) and

(9).

22

2. Preparation ofDry. Deoxygenated Nitrogen

Bottled nitrogen was bubbled through a series of traps. The first one contained

Fieser's solution44 for the adsorption of oxygen. The second one was empty to prevent

crossover. The third and fourth traps contained , respectively, concentrated sulfuric

acid and sodium hydroxide pellets. Those last two traps were for removal ofwater

vapor.

3. Preparation of Fieser's Solution44

The solution was prepared by dissolving 20 g of potassium hydroxide in 100

ml ofwater and adding 2 g of sodium anthraquinone - p - sulfonate and 15 g of sodium

hyposulfite ( Na2S204 ) to the warm solution. The mixture was stirred until a clear,

blood-red solution results and this red solution was allowed to cool to room

temperature. Traces of oxygen in the nitrogen were removed by passage of the gas

through a trap containing this solution.

The above procedure was applied to all of our hydroboration-oxidation

reactions.

44Fieser, L. F., Fieser, M. Reagents For Organic Reactions, JohnWiley and Sons: New York

1967; p 393.

23

4. Hydroboration-oxidation of Styrene using BHvTHF

withWilkinson's Catalyst

All the set-up, nitrogen, and glassware went through the same procedures as

described in experiment 1.

A dry three-necked 250 ml flask was charged with 2.08 g ( 20 mmol ) styrene.

The system was then reflushed with nitrogen for several minutes, and 0.04 g ( ~ 0.2%

mol )Wilkinson's catalyst was added to this reaction flask. Following that addition, 20

ml ( 20 mmol ) BH3-THF ( 1.0 M THF solution ) was added to the dropping funnel

with a syringe, then added dropwisely to the reaction flask. The reaction mixture was

stirred at the room temperature for 1 hour, cooled in an ice bath, and then 10 ml of a

30% H2O2 solution and 10 ml of 3M NaOH were added to the reaction mixture. Care

was taken to keep the solution slightly alkaline. The reaction mixture was stirred for 3

hours and the resulting productwas allowed to reach room temperature.

Extraction of the alcohol products was carried out with 3 x 20 ml of anhydrous

ethyl ether. The combined ether extracts were washed with 20 ml of saturated sodium

bicarbonate solution and 2 x 20 ml of distilled water. Then the ether layer was

separated and dried over anhydrous magnesium sulfate.

The productmixture was analyzed by GC/MS spectrometry. Mass spectra of

C6H5CHOHCH3 and C6H5CH2CH2OH were same as the previous experiment. The

retention times as shown on GC/MS spectra were 1.770 min for (9) and 1.902 min for

(8). The mass spectra were compared with those from authentic samples from Ardrich

company.

24

BH3-THF, RT, lh NaOH, H202-a*-

tzt:**~

Wilkinson's Cat. H,0

65.9%

(8)

yOH

OH

34.1%

(9)

The total yield of alcohol for this reaction was 67.1% . The yield was

determined by total weight of product after evaporating solvent andmultiplication by

the GC percentage ofproducts (8) and (9) in the total productmixture.

25

5. Hydroboration-oxidation of Styrene with Catecholborane

Nitrogen and glasswares was subjected to the same procedure as described in

experiment 1.

A dry three-necked 250 ml flaskwas equipped with magnetic stirred bar and a

condenser. After cooling the system to room temperature under a nitrogen stream, 5 ml

of the fresh dry THF was added to the reaction flask, the system was then flushed

again with nitrogen for several minutes, and finally the flask was charged with 2.08 g

( 20 mmol ) styrene and 2.40 g ( 20 mmol ) of catechoborane as quickly as possible

under a blanket of nitrogen. The reaction mixture was stirred at room temperature for 1

hour, cooled in an ice bath, and to this was added dropwise 10 ml of a 30% H2O2

solution and 10 ml of 3M NaOH solution. Care was taken to maintain the solution at a

slightly alkaline pH ( ~ 8 ). The reaction mixture was stirred for 3 hours and the

reaction mixture was allowed to reach room temperature.

Anhydrous ethyl ether (3 x 20 ml) was used to extract the alcohol products. The

combined ether extracts were washed with 2 x 20ml of saturated sodium bicarbonate

solution, and 20 ml of distilled water, and then the ether layer was separated and dried

over anhydrous magnesium sulfate.

The productmixture was analyzed by GC/MS spectrometry. Mass spectra of

C6H5CHOHCH3 and C6H5CH2CH2OH were same as the previous experiment. The

retention times ( GC/MS ) were 1.982 min and 2.437 min respectively. And the Mass

spectra were compared with authentic sample from Aldrich company.

26

CT-o\W-

RT,lh

NaOH, H202 y^V

S^

yOH

OH

v^

73.7%

(8)

26.3%

(9)

Only 3.8% of the styrene was consumed. This result was measured by GC.

27

6. Hydroboration -oxidation of Styrene using Catechoborane

withWilkinson's Catalyst

The setup, nitrogen, and all glassware went through the same procedures as

described in experiment 1.

The 250 ml flask was charged with 5 ml of fresh THF and 2.08 g (20 mmol )

styrene was added under a stream of nitrogen, then 2.40 g ( 20 mmol ) of

catecholborane and 0.04 g ( ~ 0.2% mol ) Wilkinson's catalyst was added to the

reaction flask. The reaction mixture was stirred at the room temperature for 1 hour,

cooled in an ice bath, and then 10 ml of a 30% H2O2 solution followed by 10 ml of 3M

NaOHwere added to the flask. The reaction mixture was stirred for 3 hours with

cooling and the reagents was allowed to reach room temperature.

Anhydrous ethyl ether 3 x 20 ml was used to extract the alcohol products. The

combined ether extracts were washed with 20 ml of saturated sodium bicarbonate

solution and then 2 x 20 ml of distilled water; the ether layerwas separated and dried

over anhydrous magnesium sulfate. The product mixture was analyzed by GC/MS

spectrometry. Mass spectra of C6H5CHOHCH3 and C6H5CH2CH2OHwere same as

the previous experiment. The GC/MS retention times were respectively, 1.864 min and

2.026 min

The product mixture was also analyzed by gas chromatography ( HP 5890A )

The retention times for authentic samples of C6H5CHOHCH3 (9) and

C6H5CH2CH2OH (8) ( Aldrich company ) were 4.787 min and 5.084 min. The

retention times for the reaction product mixture were respectively, 4.779 min and 5.078

min, clearly in good agreement with the authentic samples.

28

B-HRT, 1 h

Wilkinson's Cata.

NaOH, H,02^2

V

14.1%

(8)

OHOH

85.8%

(9)

The total yield of this reaction was 71.5%. The yield was determined by the

same method as in experiment 1.

29

If the reaction time was reduced to half an hour different results were obtained.

B-HRT, 0.5 h

Wilkinson's Cata.

NaOH, H202

3.1%

(8)

yOH OH

96.9%

(9)

The product mixture was again analyzed by gas chromatography ( HP 5890A ).

The retention times for standard samples of C6H5CHOHCH3 and C6H5CH2CH2OH (

from Ardrich company ) were 4.787 min and 5.084 min. The retention times for

reaction product mixture were respectively, 4.776 min and 5.075 min. The yield of this

reaction was 59.1%. The work up and yield determination were same as in previous

experiment.

30

Hvdroboration-oxidation of 2.3-Dihvdrofuran

Hydroboration-oxidation of 2. 3-Dihydrofuran with BHq-THF

All the glassware was predried in an oven at 150C for 24 hours, assembled

hot, and allowed to cool under a stream of nitrogen ( purified by Fieser's solution,

NaOH, H2SO4 ).

A 250 ml flask was equipped with a magnetic stirring bar, a reflux condenser,

and pressure-equalizing dropping funnel. After cooling to room temperature under a

nitrogen stream, the reaction flask was charged with 10.5 g (150 mmol) or 3.5 g

(50 mmol) of 2,3-dihydrofuran by removing the condenser and adding the 2,3-

dihydrofuran as quickly as possible under a blanket of nitrogen; the system was then

flushed again with nitrogen for several minutes, then 50 ml ( 50 mmol ) ofBH3THF

complex ( 1.0M THF solution ) was added to the dropping funnel with a syringe.

Hydroboration was achieved by the slow dropwise addition of the BH3THF

solution to the flask. Following addition, the clear, colorless reaction mixture was

stirred at room temperature for 2 hours to complete the reaction. At this point 50 ml of

3M aqueous sodium hydroxide was added to the reaction mixture. Then 25 ml of 30%

aqueous hydrogen peroxide was introduced into the dropping funnel and added

dropwise to the stirred reaction mixture at a rate such that the temperature of the reaction

mixture did not exceed approximately 50C. The reaction mixture was stirred at room

temperature overnight.

Anhydrous ethyl ether (3 x 50 ml) was used to extract the products, and the

combined ether extracts were dried over anhydrous MgS04 , The ether was evaporated

31

resulting in 10.51 g of crude product. GC/MS spectroscopy results are shown in tables

1 and 2 below.

3BH3 THF

+ CH^=CHCH?CH9OH2^n2v

( H )

H202, NaOH

OH

HOCH2CH2CHCH3

( 12 )

HOCH2CH2CH2CH2OH

( 13 )

Table 1 : Hydroboration-oxidation of 2,3-dihydrofuran

ratio of

reactants

3:1

% 10 % 11 % 12 & 13 % yield

uncatalyzed 73.4 22.3 4.4 38.4

catalyzed 81.5 7.6 10.9 26.6

Note : In Table 1, the ratio of 2,3-dihydrofuran to BH3-THF is 3: 1, and"catalyzed"

meansWilkinson's catalyst was used in the reaction.

32

Table 2 : Hydroboration-oxidation of 2,3-dihydrofuran

ratio of

reactants

1:1

% 10 % 11 % 12 & 13 % yield

uncatalyzed 55.0 41.8 3.7 66.1

catalyzed 50.0 47.2 2.8 50.2

Note : In Table 2, the ratio of 2,3-dihydrofuran to BH3-THF is 1:1, and"catalyzed"

meansWilkinson's catalyst was used in the reaction.

33

Preparation of Dimpthvl Bievclor2.2.11hepra-2.5-diene-2.3-

Dicarboxylate

>0,178UC 2

qooch3

CH2C12

OOCH3

-? COOC H

COOC H3

(14)

A fractional distillation apparatus was set up in the hood with a 200 ml round

bottomed flask, to which was added 40.0 g ( 0.30 mol ) of dicyclopentadiene. A 400

ml receiving flask was attached and in this was placed 77 g ( 0.54 mol ) of dimethyl

acetylenedicarboxylate dissolved in 250 ml CH2C12. The dicyclopentadiene was slowly

heated to avoid the distillation of the dimer. And cyclopentadiene (b.p.45-47C) was

distilled into the receiving flask in a dropwise fashion. The reaction mixture was

allowed to stand overnight at room temperature.

34

Upon evaporating the solvent ( rotary evaporator ) ,113.00 g of pale yellow oil

( in quantitative yield and identified !H NMR to be dimethylbicyclo [2,2,l]-hepta-2,5-

diene-2,3-dicarboxylate ) was obtained.

*H NMR data : Solvent acetone - d6

5 2.1

8 6.9

5 3.85

5 2.2

5 3.7

35

Preparation of dimerhvl tetra-cvclor 2.2.1.0^.0 H]

heptane-2.3-dicarboxylate45

^rCOOCH3 hx>

COOC H3

(14)

COOCH

COOCH3

(15)

Freshly prepared norbornadiene dimethylester (14) weighing 100 g ( 0.48 mol )

was dissolved in 1000 ml ethyl ether. The solution was placed in a 1-liter Pyrex

photochemical reaction vessel ( see Figure 3 ) and stirred with a magnetic stir bar. Then

this solution was irradiated using the 450 WattHanovia high pressure mercury vapor

lamp. The lamp was located in a quartz immersion well. The quartz immersion well

was placed in the 1 -literPyrex photochemical reaction vessel and cooledwith water

flowing around the jacket surrounding the lamp. The reaction vessel was equippedwith

a reflux condenser. The whole photochemical reaction vessel was covered with

aluminum foil, and a N2 atmosphere was maintained during the entire reaction. The

reaction mixture was irradiated for 4.5 hours. Then evaporation of the solvent gave a

45 McCulloch, A. W., Mclnnes, A. G., Smith, D. G. and Walter, J. A. , Can. J. Chem. 1976, 54,

2013.

36

pale yellow oil. The *HNMR spectrum indicated that unreacted starting material as the

only significant product. No successful results were obtained, even if the reaction time

was increased from 4.5 hours to 8 hours, 24 hours, 48 hours or 72 hours. The amount

of norbornadiene-dimethylester (14) was decreased from 100 g ( 0.48 mol ) to 50 g

( 0.24 mol ) and dissolved in 1000 ml ethyl ether and irradiated again for each of 8

hours, 24 hours and 48 hours. The !H NMR spectrum again indicated only unreacted

startingmaterial.

37

Figure 3.: 1-liter Pyrex photochemical reactionapparatus:46

TOPOWER SUPPLY

WATER

GROUND

GLASS

JOINT

SOLVENT LINE-

HIGH PRESSURE_MERCURY

STIRRING BAR

WATER

PYREX

REACTION FLASK

QUARTZ IMMERSIONWELL

SOLVENTAND SUBSTRATE

46Kevin Gillman, M.S. Thesis, Rochester Institute of Technology, 1991.

38

Preparation of Bicvclor2.2.11hepta-2.5-Dicarhoxvlic Acid4748

OOH

COOH

Freshly prepared cyclopentadiene (~ 50 ml ) was slowly added to 50.0 g

( 0.44 mol ) of acetylene dicarboxylic acid which had been dissolved in 200 ml of

anhydrous ether and cooled in an ice bath. The solution was vigorously stirred for four

hours and the ice bath was allowed to reach the room temperature. The solution was

then heated for ten minutes on a steam bath and then cooled in an ice bath . After 30

minutes of stirring, a precipitate formed, and the mixture was stirred for another hour.

The solid was collected by filtration and more precipitate was obtained by evaporation

of about one halfof the ether layer. The combined solids were then dissolved in hot

water, treatedwith charcoal, filtered, and allowed to crystallize ( in refrigerator )

overnight. After filtration, the resulting solid was dried in a desiccator for 3 days. In

this way 47.30 g ( 59.7 % ) of norbornadiene dicarboxylic acid (16) was obtained of

melting point : 165 - 167C

47 Organic Synthesis, collective vol. II, P 10.

48 Greenwald, B., M.S. Thesis, Rochester Institute of Technology, 1971.

39

H^.M.R data : Solvent, acetone - d6

5 2.2 5 2.3

5 7.0

5 5.7

OH

OH

/5 4.15

40

Preparation of tetracvclor2.2.1.Q2A0Ml

heptane-2.3-Dicarhoxylic Acid

( 16 ) (17)

The same 1-liter Pyrex photochemical reaction vessel was used in this

experiment. First 45.52 g of dried norbornadiene dicarboxylic acid was dissolved in

1000ml ethyl ether. The solution was irradiated for 10 hours using the 450Watt

Hanovia high pressure mercury vapor lamp, while being stirred under an N2

atmosphere. Evaporation of the solvent gave a tight yellow precipitate. The precipitate

was recrystallized from anhydrous acetone. At the end of this period, 35.69 g

(78.41%) of quadricyclene dicarboxylic acid (17) was obtained.

The product gave the characteristic complex melting behavior ( similar to that

recorded49); at 235C it began to melt, at 240C it began to foam and turned brown, at

255C it stopped foaming and a brown powder was left which did not melt until

280C.

*H NMR. data : Solvent DMSO - de,

m - 5 1.9 to 5 2.8 integrates for 8H

49 Cristol, S. J. and Snell, R. L. J. Am. Chem. Soc. 1958, 80, 1975.

41

HvdrohoraHon-oxidation of Quadricyclene Dicarboxylic Acid with

BHvTHF Promoted hv Wilkinson's Catalyst

The setup, nitrogen, and all glassware went through the same procedures as

described in experiment 1.

The 250 ml flask was charged with 20 ml ofmethanol and 1.80 g (10 mmol )

quadricyclene dicarboxylic acid was added under a stream of nitrogen, then 15 ml ( 15

mmol ) ofBH3THF and 0.02 g ( ~ 0.2% mol )Wilkinson's catalyst was added to the

reaction flask. The reaction mixture was stirred at the room temperature for 24 hour,

cooled in an ice bath, and then 10 ml of 95% ethanol and 10 ml of a 30% H2Q2

solution followed by 10 ml of 3M NaOH were added to the flask. The reaction mixture

was stirred for 24 hours with cooling and the reagents was allowed to reach room

temperature.

At the end of this experiment, a light yellow precipate ( 0.56 g ) was obtained.

This precipate did not dissolve in THF, methanol, and DMSO and thus could not be

analyzed.

42

Results and Discussion

Hydroboration of Stvrene with BH^THF

As already mentioned in the introduction, unlike other terminal olefins such as

1- butene, and 1-pentene, hydroboration of styrene with sodium borohydride and

boron trifluoride etherate in diglyme gave only 80% addition of the boron to the

terminal carbon position, and 20% to the secondary carbon50. Similar results have been

observed in our lab when we used BH3THF as a hydroboration reagent instead of

sodium borohydride and boron trifluoride etherate (B2H6). Our results were 80.7%

addition of the boron to the terminal position and 19.3% to the secondary carbon. Thus

electronic effects play an important role in influencing the direction of addition of the

boron-hydrogen moiety to the carbon-carbon double bond.

All available evidence indicates that the addition of the boron-hydrogen moiety

to olefins involves a four-centered transition state51. The boron-hydrogen bond in

hydroboration agent is presumably polarized, with the hydrogen having some hydridic

character. In styrene, as a result of conjugation, the required unshared pair of electrons

can be brought to the terminal carbon atom by means of the polarization shown in

structure 18 52,

50 Brown, H. C. and Zweifel, G. /. Am. Chem, Soc. 1960, 82, 4708.

51Brown, H. C. and Zweifel, G., /. Am. Chem, Soc. 1961, 83, 2544.

52 Wheland, G.W.,"

Resonance in organicChemistry"

John Wiley & sons, Inc., NY 1955.

43

NVCH=^CH2

(18)

1 '/H----B/

5-

5+

As a result, electronic shifts can be applied to explain the preferred addition of

the boron atom to the terminal position. Steric effects also contribute to this anti-

Markovnikov addition.

It is known that the phenyl group can also stabilize a negative charge in the a-

position, and thus electrons can also be brought to the cc-carbon atom by means of the

polarization shown in structure (19). This is the reason for the enhanced addition of

boron atom at oc-carbon position.

CH, 'B~H. / >

(19)

This mechanism would place the boron at the a - position. The transition state

would be stabilized by anelectron-

withdrawing substituent, such as p-chloro-, and

made less stable by an electron supplying substituent, suchasp-methoxy-

group.

The first (18) of these two polarizations is apparently more important and this is why

the reaction gives more additionof the boron to the terminal position.

44

Hydroboration of Stvrene with Catecholborane

The hydroboration of styrene using catecholborane at room temperature over 1

hour gave 73.7% addition of the boron to the terminal position and 26.3% addition of

the boron to the secondary carbon. Only 3.8% of styrene was consumed. Thus anti-

Markovnikov addition still dominates the addition. These results are reasonable

because, as mentioned in the introduction section, electron donation from the adjacent

oxygenmakes catecholborane a much weaker Lewis acid. This means that

catecholborane is a much weaker hydroboration agent than borane agent. As a result,

the hydroboration with catecholborane is very slow at room temperature.

Hydroboration of Stvrene promoted by

Wilkinson's Catalyst

Mannig and Noth first reportedWilkinson's reagent catalyzed hydroboration53

and thus a new facet of hydroboration was revealed.We have used theWilkinson's

catalyst to promote hydroboration of styrene using catecholborane and BH3THF . Our

results showed predominantMarkovnikov selectivity with catechoborane and increased

Markovnikov selectivity withBH3THF in the presence ofWilkinson's catalyst. In the

absence ofWilkinson's catalyst, however both reagents afforded the anti-Markovnikov

predominant products. The results are summarized in Table 3.

53Mannig D.; Noth H., Angew. Chem., Int. Ed. Engl. 1985, 24, 878.

45

Table 3 Hydroboration of Stvrene promoted with

Wilkinson's Catalyst

Reagent Catalyst %Anti-Ma

%Mb

% Yield Time

CBCNo

73.7 % 26.3% 3.8% 1 h

CB Yesd14.2% 85.8% 71.5% 1 h

CB Yes 3.1% 96.9% 59.1% 0.5 h

BH3THF No 80.7% 19.3% 78.9% 1 h

BH3THF Yes 65.9%) 34.1% 67.1% 1 h

a. % ofAnti-Markovnikov product (C6H5CH2CH2OH)

b. % ofMarkovnikov product (C6H5CH2OHCH3)

c. CB means catecholborane

d. 0.2% mol ofWilkinson's catalyst was used.

In Hayashi 's paper54, they claimed that high regioselectivity (Markovnikov

addition ) was only observed with rhodium complexes that have tertiary phosphine

ligands and a positive charge on the rhodium atom. For example they found that the

hydroboration reaction of styrene with catecholborane in THF at25 C for 30mins in

the presence of 1% mol of rhodium catalyst prepared in situ by mixing [ Rh (COD)2]

BF4 and 1,4 -bis(diphenylphosphino)butane (dppb) followed by oxidation gave 99%

54 Haysshi, T., Matsumoto, Y. and Ito Y. ,/. Am. Chem. Soc. 1989, 111, 3426-3428.

46

of ct-phenylethanol regiospecifically (C6H5CHOHCH3 / C6H5CH2CH2OH~ 99/ 1).

In this case,Markovnikov addition product was the major product. But when

Wilkinson's catalyst was used, the anti - Markovnikov product was the major product.

According to their results, hydroboration of styrene with catecholborane in the presence

of 1 mol % ofWilkinson's catalyst gave the following ratio: C6H5CHOHCH3 /

C6H5CH2CH2OH = 10 / 90. The yield was 79%.

David A.Evans'

researchgroup55 have studied the hydroboration of styrene

with deuteriocatecholborane promoted byWilkinson's catalyst. They observed that the

reaction of excess olefin with deuteriocatecholborane under standared conditions

afforded only one deuterium-containing product, 1-phenyl-:deuterioethanol (100%,

C6H5CHOHCH2D).

Our reactions and observations were more similar toEvans'

observations.

Hydroboration of styrene with catecholborane in the presence of 0.2 mol % of

Wilkinson's catalyst at room temperature for half an hour provided 96% of a-phenyl

ethanol Markovnikov product. Also from our results, it seems that in the presence of

Wilkinson's catalyst with less reaction time, moreMarkovnikov product

( C6H5CHOHCH3 ) was formed. Hydroboration of styrene with catecholborane for

one hour gave 85.8% ofMarkovnikov product, whereas hydroboration of styrene with

catecholborane for half an hour gave 96.9% ofMarkovnikov product. Even though the

mechanism of hydroboration of styrene with catecholborane withoutWilkinson's

catalyst offerded the anti- Markovnikov product as major product, this process

( withoutWilkinson's catalyst ) is much slower than the catalytic process ( with

Wilkinson's reagent ), and the result of these two competing processes was largely

Markovnikov addition product.

55 Evans D. A. and Fu, G. C., /. Org. Chem. 1990, 55, 2280-2282.

47

We also hydroborated styrene with BH3THF in the presence ofWilkinson's

catalyst. Compared to catecholborane, BH3THF is a much stronger hydroboration

reagent. Our results indicated that withoutWilkinson's catalyst, borane ( BH3THF )

reagent can hydroborate styrene rapidly and providemainly anti-Markovnikov addition

product. When we appliedWilkinson's catalyst to the hydroboration of styrene with

BH3THF, we found that moreMarkovnikov addition product was obtained. It

should be noted that unlike the hydroboration with catecholborane, the hydroboration

using BH3THF gave anti-Markovnikov addition as major product both with and

withoutWilkinson's catalyst.

The effect of usingWilkinson's catalyst was an increased percentage of

Markovnikov addition. These facts suggested that hydroboration of styrene controlled

by the catalyticmechanism provides Markovnikov addition product, whereas

conventional hydroborationmechanism (without Wilkinson's catalyst) providesanti-

Markovnikov addition product.

The difference between using BH3THF and catecholborane can be explained

by the hydroboration rate. Since BH3THF is a much more reactive agent than

catecholborane ,the rate of hydroboration of styrene using BH3THF through the

conventional mechanism (withoutWilkinson's catalyst) is apparently faster than the rate

by the catalytic mechanism. This is why the anti-Markovnikov addition products were

major products even whenWilkinson's catalyst was used. However, the catalyzed

process was fast enough to cause an increased percentage ofMarkovnikov addition

product to be obtained. On the other hand, the hydroboration using catecholborane

withoutWilkinson's catalyst is very slow as demonstrated by only a 3.8% conversion

of styrene. Thus whenWilkinson's catalyst was used, the catalytic process heavily

dominated the hydroboration reaction and gave Markovnikov addition product as major

48

product. The very slow hydroboration process through the conventional hydroboration

mechanismmay still be present and this could give mainly anti-Markovnikov product.

The percentage of anti-Markovnikov product increased with reaction time as shown in

Table 3. This suggests that the rate of the non-catalytic process becomes more

significant compared to the catalytic process as the reaction proceeds. For better

understanding, let us look the proposed mechanism of the hydroboration catalyzed by

Wilkinson's catalyst.

Mechanism of Rhodium Catalyzed Hydroboration of Olefins

Mannig andNoth56 have suggested a mechanism for catalyzed hydroboration of

olefins, which is analogous to that proposed for the much more thoroughly investigated

rhodium - catalyzed hydrometalation reactions such as hydrogenation, hydrosilation

and hydroformylation57. The mechanism is illustrated as in Figure 4:

56Mannig, D., and Noth, H., Angew. Chem. Int. Ed. Engl., 1985, 10, 878.

57 Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G., Principles and Applications of

Organotransition Metal Chemistry ; University Science Books : Mill Valley, CA 1987.

49

Figure 4: Proposed Reaction Mechanism for a Wilkinson's Reagent

Catalyzed Hydroboration Reaction

L = PPh3

reductive

elimination

rV,

H

>( B-Rh\()/

| VL

CI

hydride

migration

(alkene insertion)

RhL3Cl

-L

RhL2Cl

( \-RhV | VL

CI

olefin

binding

According to the above mechanism, only the regiospecific incorporation of

deuterium at C2 of the product alcohol should be expected. After isotope labeling

studies carried out on the rhodium catalyzed olefin hydroboration reaction by Evans and

Fu55, it was found that the mechanism of these reactions is not as straightforward as

Figure 4 above suggested. When they usedWilkinson's catalyst to catalyze

hydroboration of 1 - decene with deuteriocatecholborane ( 2 mol % catalyst, THF,

50

20C) followed by oxidation, they did not find simple regiospecific incorporation of

deuterium at C-2 of the isolated 1-decanol as the mechanism in Figure 4 suggests.

Instead, a significant proportion of the deuterium in the product alcohol was found at

the hydroxyl-bearing carbon. But when they usedWilkinson's catalyst to catalyze the

hydroboration of styrene with deuteriocatecholborane, they found deuterium

corporation exclusively in the terminal carbon position of theMarkovnikov product.

These results indicated that the mechanisms of the hydroborations of the 1-decene and

styrene are not completely the same. The different hydroboration resultsare rationalized

in Figure 5.

In the case of 1-decene, the regioselectivity determining step is reductive

ehmination step. To explain the incorporation of deuterium at C-l, the hydride

migration step should be considered to be areversible step. In the case of styrene, the

regioselectivity determining step is an irreversible hydridemigration step. Since these

two reactions have different regioselectivity deterrnining steps and different

reversibility, the labeling study showed different results.

51

Figure 5: Regioselectivity Determining Step of Styrene and 1-Decene in

the Mechanism of Hydroboration Promoted by Wilkinson's Catalyst

<*^n Oct

(RO)2B-H

Rh(PPh3)3Cl

.n-Oct

(RO)2B-Rh

H/

H

'n-Oct

(RO)2B-Rh

yPh

I(RO)2BRh

H/

regioselectivity-

determining step !

I

Ph

H

(RO)2B -Rh

regioselectivity-

determining step

H

-Oct

H

Ph

(RO)2B

(RO)2-B

Recently, Zhang et al. also proposed the mechanism of

hydroboration for styrene promoted byWilkinson's catalyst. It is shown in the Figure

6. In this proposed mechanism, the insersion of an olefin toM-H bond or (M-Bbond)

52

mechanism, the insersion of an olefin toM-H bond or (M-Bbond) may occur in two

different ways: primary insertion and secondary insertion.

Our observations led us to believe that the secondary insertion ( to form the

secondary system, ArCH(CH3)MB was the predominant step, sincehydroboration-

oxidation of styrene with catecholborane promoted byWilkinson's catalyst ( for half an

hour ), gave 96.9% Markovnikov product and only 3.1% anti-Markovnikov product.

The domination of the insertion on the secondary carbon can be explained by the

formation of tj3- benzyl complex as illustrated in Figure 7.

53

Figure 6: Proposed Mechanism for Hydroboration of Styrene Promoted

by Wilkinson's Catalyst:

ArCH=CH2

ArCH-CH ArCH=CH2ArLH-CH2CB

,2

ArCH=CH2

ArCHCH3^ ArCHCH3

M

I

B M B

ArCH2CH2

IMB

ArCH2CH2

B

secondary insertion primary insertion

54

Figure 7 rj3- Benzylrhodium Intermediate

Ph3P B^

Ph3P

\ /Rh

CI

PnK^ h

The enhanced stability ofT|3 - benzyl complex makes the secondary

insertion a preferred step . Such T|3- complexs have been reported. This mechanism

explains why the hydroboration of styrene mainly gave theMarkovnikov addition

product as observed in our experiments.

Hydroboration of 2.3 - Dihvdrofuran Promoted

bv Wilkinson's Catalyst

The main purpose of this part of the project is to study the effect ofWilkinson's

catalyst on hydroboration of heterocyclic olefins in an attempt to find the optimum

conditions for these systems.

In 1985, Brown's research group studied the hydroboration of 2,3-

dihydrofuran with BH3-SMe2. They found that the hydroboration of 2,3-

dihydrofuran with BH3-SMe2 ( 3: 1 molar ratio ) at 0C for 2 hours proceeded to give a

mixture of trialkylborane and borinate ( 14 ). Oxidation afforded a mixture of3-

hydroxytetrahydrofuran ( 10, 88% ) 3-buten-l-ol ( 11, 4% ) and 1,3-and 1,4-

butanediols ( 12 and 13, 6% ) . The formation of these products can be rationalized in

55

the following Figure 8 ( the mechanism has been outlined on p. 13 of the introduction

section ):

Figure 8 : Hydroboration-oxidation of 2,3-dihydrofurane

BH, THF

2h

+ CHi=CHCH2CH2OH

11

H202NaOH

^oA^

H202NaOH

HOCH2CH2CHCH312

+

HOCH2CH2CH2CH2OH

13

56

We appliedWilkinson's catalyst to 2,3-dihydrofuran and the results are

summarized in Table 2 and Table 3 of the experimental section.

These results indicate thatWilkinson's catalyst caused different effects when the

ratio of reactant to hydroboration reagent was changed from 3:1 to 1:1. When the ratio

of 2,3-dihydrofuran to BH3THF was 3:1, the ratio ofmain product ( 3-

hydroxytetrahydrofuran, 10 ) in the product mixture was 73.4% in the absence of the

Wilkinson's catalyst. In the presence ofWilkinson's catalyst, the ratio was 81.5%.

However, when the ratio of 2,3-dihydrofuran to BH3THF was changed from 3:1 to

1:1, the ratio of 3-hydroxytetrahydrofuran in the product mixture was 55.0% in the

absence ofWilkinson's catalyst. It was changed to 50.0% in the presence of

Wilkinson's catalyst. Since the mechanism of hydroboration-oxidation of heterocyclic

olefins is not yet known, we are still unable to explain these results.

The product yield was lower withWilkinson's catalyst than without

Wilkinson's catalyst. The possible reason for this may be the following: since 2,3-

dihydrofuran has an electron rich oxygen andWilkinson's catalyst has a vacant site, the

electron rich oxygen might bind to theWilkinson's catalyst such that further reaction

may be suppressed. In other words,theWilkinson's catalyst might be deactivated by

2,3-dihydrofuran. Further evidence is needed to test the above suggestion. Evans has

also printed out thatWilkinson's reagent is subject to oxidation which can affect the

product ratios.

These results also showed that in the presence of excess hydroboration reagent,

the ratio of the main product (3-hydroxytetrahydrofuran, 10 ) in the total product

mixture was much lower. This is because the presence of excess hydride cause ring

cleavage of the alkylboranes, which leads to side products.

57

Hydroboration of the Cyclopropane Ring in a Quadricyclene System

promoted hv Wilkinson's Catalvat

Other research workers in our group were studyingWilkinson's catalyst

promoted hydroboration of a cyclopropane ring in quadricyclene. One ofmy research

projects was to hydroborate a cyclopropane ring in quadricyclene dimethylester or

quadricyclene dicarboxylic acid. The new reaction that we plan to perform is:

COOCH3

COOCH3

1) BH3,THF or CB, WILK. Cat.

2) H202, NaOH, H20

COOCH3

COOCH3

-*?

OH H

We prefer to use diester rather than diacid as a substrate for this reaction,

because the hydroborated diacid intermediatemight be susceptible to protonolysis by

58

the rest of the diacid58. One typical example to illustrate the above point is shown

below.

RSCH 2CH= CH2_ RSCH2CH2CH2Jg2^RSCH 2CH 2CH3

/B\

Therefore, we may not be able to use the diacid for the hydroboration

experiment because the following reaction may happen.

Ao/ \

COOH

COOH

We first attempted to prepare the quadricyclene dimethylester as the starting

material for the hydroboration reaction. In principle, the synthesis can be achieved

through the (2+2) addition of norbornadiene dimethylester.

Norbornadiene dimethylester was successfully prepared by reaction of

cyclopentadiene with dimethyl acetylenedicarboxylate. The Diels-Alder addition (2+4)

of two reactants gave us norbornadiene dimethylester. The product was verified by

200MHz *H NMR spectra.

58 Brown ,H. C.and Singaram, B., Pure and Appl. Chem., 1978, 59, 879.

59

Norbornadiene dimethylester synthesized in the previous experiment was placed

in 1 -literPyrex photochemical reaction apparatus and irradiated for 4.5 hours. The

*H NMR spetra indicated that the expected (2+2) addition had not happened. To study

whether the reaction time had an effect on the addition, we performed our experiments

with the different irradiation time ranging from 4.5 hours to 8 hours, 24 hours, 48

hours and 72 hours. The *H NMR analysis still indicated that the (2+2) addition

product was not present in the mixture. We also experimented with different (more

dilute) concentrations of norboranadiene dimethylester to avoid polymer formation.

The amount of starting norbornadiene dimethylester decreased from 100 g (0.48M) to

50 g (0.24 M), and then the solution was irradiated for 8 hours, 24 hours and 48 hours

respectively. An analysis of the product mixture using 200MHz *H NMR still

showed none of the desired 2+2 addition product.

The above results suggested that we may not be able to use norbornadiene

dimethylester directly to synthesize quadricyclene dimethylester. One possible reason is

that norbornadiene dimethylestermay form polymer under irradiation, although the

concentration study did not show this.

Because of the difficulty in synthesizing quadricyclene dimethylester from

norbornadiene dimethylester, we decided to use quadricyclene dicarboxylic acid for the

hydroboration study despite thepossible problem mentioned above.

First, we successfully prepared norbornadiene dicarboxylic acid by a 2+4

Diels-Alder addition of cyclopentadiene and acetylene dicarboxylic acid. The product

was verified by !H NMR spectrum.

Norbornadiene dicarboxylic acid prepared in the above experimentwas

irradiated for 10 hours. The reaction product was analyzed by *H NMR. The *H

NMR indicated that there was no norbornadiene dicarboxylic acid present. The olefin

60

proton signal at 8 7.0 had disappearedwhich proved only quadricyclene dicarboxylic

acid was present.

Hydroboration-oxidation of Quadricyclene diearhoxvlic acid with

BH3 THF promoted by Wilkinson's catalyst

The precipitate from reaction mixture could not dissolve in THF, methanol, and

DMSO. Good reaction and workup procedures are needed for the study

Furture work : first someone can hydroborate quadricyclene dicarboxylic acid

directly using hydroboration reagent BH3THF ,catecholborane or other reagents to

study the hydroboration of cyclopropane ring with and without the presence of

Wilkinson's catalyst. Secondly, we can synthesize quadricyclene dimethylester from

quadricyclene dicarboxylic acid and then hydroborate quadricyclene dimethylester.

61

<o-

00-

u

m

L^

w

l\>

62

S RS

aa

-CCM^. -M

l*3O (M ^ IP IT o

bocoicn ovaw a. ru

o&ou A a"*

C\

t o Gicnotn-c/:x &B<szk kGO ^iuukkZ&K

63

O) -* * ni-

am |O K OtClCM-"

. i oirmr.fn

'itDo ry -r^irjin

t*D*f, *riTlTW

op 1010 ?

e

ooboic* ocaW ff Ory

ft ryJ

aal*- OO O&ruX

C eotooottto

Pff.lN W

oac-iur. t- ^L vi

5* o Rnon*-cnz Esax- Cos j3uuku.ZD.vi

\3 ZTTT

8

64

GC - Mass spectrum of the reaction of styrene and BH3THF

withoutWilkinson's catalyst

c

u

c

tt

a

c

j

a

a

Scan BB (1 .674 nm) Of ORTR:PINS 0

2.BETS-

/ 107

1. SCS-5 79

3 31 1221 ers^ 16

es

'

/ BB \3. BC4-

B

\ /

.,tl, ! Jill. .,U . lmJ, , .1.1

, ,1.

2B 4B ED BBMatt ,'Ch arga

IBB 12B

C

X1

ll

3. BC7-

2.BE7-

TI C Of ORTF): FINC.D

I

1. BE7:

B^\ *

,

Tim Cn 1 n . 1

at

a

c

It

B

C

a

a.

1. SEE "i

Scan 71 (1 . 7B2 bd j n 3 of DRTfi: PIN 3.0

\91

1 .

5.

BEB-

BE3:

BJ

ie

19

31

B3/

J....

77

//

"'1 '

122

X

1.2B 4B EQ

Matt Charp

BB IBB 1B

u

c

C

TIC of ORTR:PINC.O

3.BE7-

2BE7-

i.BE7:

13

0

__ 11 A

T (ii. 1

Mn oTofb:Pii;.&

Peakl Ret Tiee Type Width Area

1 1.276 PV O.We 1B1R4831B4

2 1.462 W 6.076

3 1.676 W 0.D35

4 1.783 *B G.W7

Start Tine

1.1S2

15321058 1.425

2339S&73 . 1.631

97?386>7 MY 1.732

65

End Tine

l.4?5

1.M8

1.732

1.914

GC - Mass spectrum of the reaction of styrene and BH3THF

withWilkinson's catalyst

u

c

13

"B

C

if

XI

CC

Scan 71 C1.77B nm) of DfiTR:5TrRENE2.D

l-3EB: ^ 1B7

3 ; 9~~^

1. BEt- / 122

S. BE3:

39

E3 .

, ,1.a

'.....I II.

'

i.ili II2B 4B EB

Mi8t/Chrgi

BB IBB 12B

TIC of DRTR: STVRENE2. O

o

c

*

a

c

a

CC

t or 7

2.BE7:

l.BE/

B

*!

LLJUi,Tin Coin.)

Scan 7? U.9B2 mm) of DRTR: 5TVRENE2 . 0

rt

9

C

X>

CC

13

AXI I | <!"

B

*>-*

31

/

4L

S3

Ma. H'Nl)

4B BB EBrm /Chap; e

IBB 1B

TIC of DRTR:STVREME2.D

u

c

A

TJ

C

JO

ec

g.Br7-

2. be?:

l.BE/:

B:

Tin* (inn.)

Pe&kt Ret Tine Type Width

t

2

3

4c

1.294 VH

1.514 VH

1.771 VH

1.996 PV

3.556 W

Area

6.fi88 17nS51?fl?1

6.053 8D3UQf3

6.635 173323161

6.638 3451964956.634 3736291

Start TiM

i.rno

1.190

1.726

1.848

3.512

End Tiee

1.480

1.668

1.843

2.149

3.61R

66

Bean 9* CI. 9*7 ttm) af OUT*.: PINCCB. D

3

u

ca

4.BCB-

l.BEE-

- S X"

.g

c

i.bes-

\ I J IBS .__

5

'5

a

ii.bcb-

- N 1 j. J / '\ IBS/

eta 4a aa bb ibb ibb it IBB

|TIC I tf OP.TP.: PINCCB. O

1.BE7

11.SC7 1

1 t.ut?I

o I a. act

tf^wj .

<u 1 8 9 4c

CQ

Tine Cum.)

H1

.

>

s

CA

"5 .

Bean TB CI. BBS rm) of OP.TP,: PINCCB. O

\ f} IB?

co

1

CQ

sC

2

S.BC4-

"2.BE4-

ji..yI'Y f. l. r

B4B

1 i SB IBB 198 BBB

laH>ll /CMrtl

o TIC Bf ORTHi PINCCB. 0

E

2u

I.BE7 I ?

00

c

a

o

c

3

a

tt

I.9E7

I.BE7

9.8E6

at

i

1 1 B 1 4

uo

Ti *ii Cat 1 n. >

Bean BE (S.SB9 aiinl of OP.TP.: PINCCB. O

t.BES* i

I.9CS'1 i -

I.BES-

\v 7 T a.BBB

i9.BE4-

. 1 '/"/'\

SB IBB I9B BBB

i.

t

Maaa/Charaa

TIC Of OP.T P.! PINCCB. D

t

t.BCri

t.azr 1i t.ac?

-

I9.BEB k ^JL 1

-

i>

19 9 4

i Tla Coin.)

P**k Rat Tim 1W ' Ar" St.rt Tiw End Tiaia

i i:i.i W 1:83 .\mili\ \:\n2.135

9 1.983 W 0.060 6060061 1.9074 2.197 fy. 5'S5 22614697- 2.135 2.26V5 2.471 W 0.044 46820719$ 2.321 2.6BE(

67

GC - Mass spectrum of the reaction of styrene and catecholborane

withWilkinson's catalyst (reaction time 0.5 hr.)

Scan B2 C1.B64 nm) of DRTR: PXNGC82. 01.3EB-

y ^i

79 1B7l.BEB-

43 SI 122

3.BE3-27 i

\

BJ M. ...i 1 Jill _~l

91

, J.4B EB BB

Miti/Chargi

IBB 12B

2. BE7

1. 3E7

1.BE7

3. BEE

B

TIC Of DRTR: PINCCB2. D

2 a 4

Ti w>m (ill n. J

Peak*

1

2

3

4

5

6

u 1.BE31c

c 5.BE41 28a

o

B

Scan 9B C2.B26 ntn) of CRTR: PINGCB2. 0

y\91

iUt.,..Ji il il >> i.

122

/

1B3/! I

131

.' 1 1 * 1 1

4B EB BB IBB 12B MB IBB

TIC Of DRTR: P1NCCB2. D

2. BE7:

1.SE7-;

1 . BE7

3.BEB-

BI 1 -4

Ti na ttii n. >

* S

Ret Time

1.252

1.509

1.553

1.860

2.023

2.162

Type Width Area Start Time End Time

UH 0.070 1089329085 1.155 1.481

UH 0.026 6609628 1.481 1.520

PB 0.042 236675122 .

189123895*1.520 1.740

BU 0.042 1.769 1.965

uu 0.039 9734965 **.% 1.965 2.095

PU 0.043 173367086 2.095 2.368

68

GC - Mass spectrum of the reaction of 2,3-dihydrofuran and BH3THF

withoutWilkinson's catalyst

.Baiatn 7B (a .BOB mlma mt ORTS.PIMQ.O

4.BEB"

>o ^1u|29 37

c

m

3.BEB-

c

2.BEB"

a

0

CC ,..|| Ii. ..Lull,

7B BB 93

< ' y142

4B BB BB 1BCMitt/Chirst

1EB 14B

TIC of DRTR: PING. 0

3.BE7- 1 '

ti

c

m2.BE7:

a

c

a 1.BE7-

CC

nj J2 4 B

Tt na (nin. )

Scan 91 CI 721 mini of DRTRsPING.O

B.BEB-j ^a 'i 1 A 2cM

4.BEB-

-B . 37 71

Ca

0

CC

2.BEB-; |nil

.ll 1 1

/ / a.

1B1

/117/

4B BB BB

MasB/Charoa

IBB 12B

rTIC Of DRTR:PING.D

3.BE7-

c

u'

c

* 2.BE7";-B

'

C ,

a

X

CC

1.BE7-

K2 4

T1 na Cm n. )

B

Peekt Ret Tiae Type Width Area Start Tiae End Tiae

1 1.265 PV 6.683 357958165 1.126 1.463

Z 1.533 W 6.653 896524266 1.463 1.655

3 1.718 W 8.666 682618936 1.655 1.919

4 2.619 BY 6.834 7288137 2.758 2.838

5 2.857 W 8.636 7683686 2.838 2.904

6 2.965 W 8.629 3516984 2.931 3.664

7 3.657 PV 6.838 2649J732> 3.664 3.186

8 3.269 W 6.824 19673863 3.233 3.313

9 3.351 w__ 8.63$ 34217593 3.313 3.426

69

GC - Mass spectrum of the reaction of 23-dihydrofuran and BH3THF

withWilkinson's catalyst

Bean 77 CI. 302 mn) of DRTR : PXNC.O

u

c

B

C

a

s>

CC

2.5EBJ

2. BEEj

1.5EBJ1.

S.BE51

*

4

li

9

1

! 7

43

32 \ 4// |/

S3 61

L ...l.llll. \ ../

7B ?3

[ /BB

/1

SB 4B SB BBMatt /Charoa

7B BB 9B

u

c

*

1.3E7

1.BE7 1 \\;XC of DRTR: PING. D

C

a

0

CC

3. BEB

B

1 2 3

Ti na Cm n. )

4 3

2.3cm

2. BE3J1. 3E3i

1. BE3l

3. BE4~i

B*m

Scan 63 (1.62B mn) of ORTR:PING.D

44

71

77 91

i. xi. y yin ii ! in. .ii 1. 1 1, . .

134

'i '"I ' '' i1

4B EB BB IBB

Mas* /ChirQi

12B

""*9r"""""l""""""f

14B

Peak! Ret Tiae

1

2

3

4

5

6

7

8

9

1.192

1.241

1.451

1.563

1.629

1.852

2.452

2.517

2.806

Type

PH

PV

W

w

w

w

w

w

BY

Width

8.622

6.666

8.624

8.629

6.831

6.621

8.644

6.642

6.623

free

2561289

878855121

2274285

.286194343

< 26211559

3838661

4699129

1498$248i

.22224535J

Start Tiae

1.167

1.214

1.438

1.464

1.582

1.789

2.418

2.486

2.735

End Tiae

1.214

1.438

1.464

1.582

1.769

1.897

2.486

2.617

2.847

70

*1

s ' i26928' 986*

dd 9*C1 2SCS

5ua f^W'CCwe*

8d 2869t2 ^8^**

I62220* tee*

Ad ecu S2'

rA

ei6e2*99E98*

8d .111192* Zft

XW38W Hxam 3dAi WSdW 1

L J --

X?3*V

v^12ICCICI 1661 MC nnr fit #Hna

f

a

5

E

uo

a

dOlS

2SCS

t.*l'*

?62**

82^*e

71

CapillaryGC spectrum of authentic P - phenylethanol sample

H OH

r\-c- c-h\=/ 1

H A

3.783

4.428

4.797

5.884

5.438

auHt 44JUL 31.

1344I34

AREA*

T

3. 763

4.426

4.767

9.664

9.456

AREA TYPE 610TH

4469314 6

1547 6

2466 66

3717666 6

164 6P

IOTH AREA*

.6623.4742

.669.61316

.672.62616

.67436.47742

.667.66161

72

apillaryGC spectrum of the reaction of styrene and catacholboranewithWilkinson's

catalyst (reaction time 1 hr. )

_j

3.781

3.881

4.776

5.362

STOP

RUNt 47 JUL 31. 1991 141 13142

AREA*

RT AREA TYPE WIDTH AREA*:

3.761 8586675 BV .662 95.36314

3.661 125131 VV .645 1.48299

4.167 46929 VV .667 .45883

4.228 23478 VV .657 .28562

4.422 2785 VP .673 .63832

. 4.776 145568 PB .672 1.63218

.5.67524812 BB .676 .26918

.5.36249763 ee .684 .55786

73

CapillaryGC spectrum of the reaction of stvrene and catacholborane withWilkinson's

catalyst (reaction time 0.5 hr. )

3.784

><- 234

4.788

3.876

> 366

STOP

UNI 48 JUL 31. 1991 14I2H53

tlX

RT AREA TYPE yiDTH AREA*

1.784 3916826 PB .66596.39917

4.234 73367 PP .6711.22791

4.766 113366 VB .8691.67959

1.678 3696 6P .674.86348

6.666 26364 PB .685.42986

74