chemistry 125: lecture 75 april 29, 2011 review: synthesis of cortisone, a natural product this for...

Chemistry 125: Lecture 75April 29, 2011

Review:Synthesis of Cortisone,

a Natural Product This

For copyright notice see final page of this file

Cortisone

based on Fieser & FieserAdvanced Organic ChemistryReinhold (1961) pp. 594-599

O

O

CH3

CH3

H

H H

OHCO

CH2OH

Louis F. Fieser (1899-1977)

Mik

ael H

äggs

tröm

Steroid work was awarded four Nobel Prizes between 1927 and 1950.

Closely related work earned another three between 1965 and 1975.

The awards in 1927 and 1928 were for determining thestructure.wrong

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Philip Hench Nobel Address

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Philip Hench Nobel Address

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Reichstein

Tadeus Reichstein Nobel Address

Fishhook to Extract Ketones :

H2N-NH-C-CH2-N(CH3)3

O+

H2N-NH-R+

EtO-C-CH2-N(CH3)3

O+

EtO-C-CH2-ClO

Cl-C-CH2-ClO

HO-C-CH3

O

H2NNH2

EtOHP/Cl2

N(CH3)3

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Cf Lect 6511 slide 3

5 were Previously

Known

Cortisol (hydrocortisone)

11

17

29 Steroids from

Adrenal Cortex

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O

O

CH3

CH3

H

H H

OHCO

CH2OH

11

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Woodward "Total" Synthesis (1951)

O

O

CH3

CH3

H

H H

OHCO

CH2OH

"Total" Synthesis Woodward (1951)

C D

BA

O

O

CH3

CH3

H

H H

OHCO

CH2OH

LiAlH4

reduction

D?C

O

CH3O

CH3

OH

D?C

O

CH3O

CH3

OH

OH

OH

D?C

CH3O

CH3

HOH

D?C

O

CH3

H

H+/H2O

OH

D?C

CH3O

CH3

HOH

CH3

C

O

CH3O

O

H

H

OH-

H

H+

+

D?C

O

CH3

H

Ac2O

Why losethe top OH

not one of these?hemiacetal

Diels-Alder

via enolate

OH allylic rearrangement

known andreadily available

+ +

CH3CO

Zn:+2

CH3CO2-

H+

cis

trans

trans

Zn

“handle”for B

“handle”for 11C=O

“handle” to modify D

Redox Analysis

"Total" Synthesis Woodward (1951)

C D

BA

O

O

CH3

CH3

H

H H

OHCO

CH2OH

D?C

O

CH3

H

OO

D?C

CH3

H

H

B

OsO4

O

D?C

CH3

H

H

B

OH

OH

O

D?C

CH3

H

H

B

O

O

H+ O=C(CH3)2

(ketal)

O

D?C

CH3

H

H

B

O

OH2 / Pd

enolate-

-

-

“Michael”(1,4 or conjugate)

addition

aldol

Robinson annulation

Protecting C=C

“handle”for A

“handle”for 11C=O

protection for D?

"Total" Synthesis Woodward (1951)

C D

BA

O

O

CH3

CH3

H

H H

OHCO

CH2OHO

D?C

CH3

H

H

B

O

O

Abbreviate Ring D(while we work on A)

O

C

CH3

H

H

B

CH3

Protectthe more

reactive position

"Total" Synthesis Woodward (1951)

C D

BA

O

O

CH3

CH3

H

H H

OHCO

CH2OH

O

C

CH3

H

H

B

CH3

O

C

CH3

H

H

B

CH3

N(CH3)PhHO

C

CH3

H

H

B

N(CH3)PhHN

CH3

C

-

-OH-

(catalytic)

NC

C

B

O

CH3

CH3

H

H

OCH3

conjugate addition

H-N(CH3)Ph

OB

H

OCH3

O

B

H O

OB

H OHO

N(CH3)Ph

- -

:

like aldol -unsaturated ketone(also an enamine)

like Claisen

HH

HH

"vinylogous”

H

LORE!

ready for aldol to A

closerto 11C=O

Robin

son?

MVK

H+

Protectthe more

reactive position

"Total" Synthesis Woodward (1951)

C D

BA

O

O

CH3

CH3

H

H H

OHCO

CH2OH

O

C

CH3

H

H

B

CH3

O

C

CH3

H

H

B

CH3

N(CH3)PhHO

C

CH3

H

H

B

N(CH3)PhHN

CH3

C

- OH-

(catalytic)

NC

OH- (strong)

H2O

ON

C

CH3

H

H

B

CH3

C OO

CH3MgBr H+C

B

O

CH3

CH3

H

H

OCH3

C

CH3

H

H

B

CH3

OO

conjugate addition

A?-

O

N(CH3)PhHlose

HOH+

++

H +H

+

HCH3enolate

"Total" Synthesis Woodward (1951)

CH3

O

C

B

O

CH3

CH3

H

H

D?

O

OA

aldol C D

BA

O

O

CH3

CH3

H

H H

OHCO

CH2OHnow work on D

A all set

"Total" Synthesis Woodward (1951)

C D

BA

O

O

CH3

CH3

H

H H

OHCO

CH2OH

CH3

H

D?

OH

OH

H+

H2O

CH3

H

O

H

O H

CH3

H

D?

O

O

I

H

HO

O-

O

Formal (or "Relay")

This conversion was known from previous cortisone studies!

1) K2Cr2O7

OB

A

C-OHCH3

H

D

O

CH3 HC

BH4-

CCH3

H

D!

O

aldol

base

-H2O

I

OO-

O

O

H/ resolved (1909 method)

-IO3- pericyclic

H

2) CH2=N2

hydrolyze acetal

new “acetal”

reduces ketone

not ester

CH3

not(luck)

precipitated 3 from 90% EtOHby natural “digitonin”

D?

O

O

J. Am. Chem. Soc.

H2

Pd

1) NaBH4

2) Ac2O

4 5 6 7 8

O

OH

But What Was the Yield?

Intellectual/Artistic Problem Solved

Sequential (39 steps @ 80%) 0.01% yield

Convergent99

99

A

B

C

D

Product

E

F

(4x9 steps + 2) 9% yield

Cortisone Synthesis (Practical)

Choose an appropriate,readily availablestarting material.

properlymethylatedtetracyclic

carbonskeleton

with properstereochemistryat key positions

and functionalgroups at or near

some of the proper positions

but

from ox bile1946-49

Merck made 1 kg cortisonefrom 600 kg

of this bile acid

?

Br?Br

Br

?O

1949Merck

$200/gm

Cortisone Synthesis (Practical)

Pregnancyhormone

~1955$0.48/gm

Abundant ina Mexican yam

Russell Marker

(1943) 10 tons

3 kg ($250,000)

1954 Strychnine Synthesis

Photos courtesy M. Saunders

“Woodward’s style is polished showing an insight and sense of proportion that afford him strong convictions, and a well developed dramatic sense.” Bartlett, Westheimer, Büchi (1969)

Nobel (1965) "for his outstanding achievements in the art of organic synthesis” .

Vitamin B12

(1973)

Albert Eschenmoser

ETH Zurich

Robert Burns Woodward

(1917-1979) Harvard

During this work RBW discovered control of stereochemistry by orbital symmetry(pericyclic reactions)

with ~100 co-workersincluding…

V. K

isak

ürek

H.C

.A.

M. S

aund

ers

postdoctoral Woodward collaborator

Yoshito Kishi(instructor Nagoya Univ.)

WOODWARD, PURE APPL CHEM 25: 283 (1971)

Kishi joined and then succeeded Woodward as professor at Harvard.

Palytoxin 62 Stereogenic Centers

42 Functional GroupsProtected 8 Different Ways

Convergent from 8 Pieces

Kishi et al. 1994

1020 stereoisomers7 E/Z Double Bonds

C123H213NO53

The FDA approved Eribulin for metastatic breast cancer on November 15, 2010

O

O

O

O O

O

O

O

O

HO

HO

MeO

O

H

H H

MeH

H

H

O O

OMe

OO

O

O

O

OO

Me

HH

H

H

H2N

OH

E7389halichondrin B C.1-C.38 macrolide

"In Vitro and In Vivo Anticancer Activities of Synthetic Macrocyclic Ketone Analogues of Halichondrin B"M.J. Towle, K.A. Salvato, J. Budrow, B.F. Wels, G. Kuznetsov, K.K. Aalfs, S. Welsh, W. Zheng, B.M.Seletsky, M.H. Palme, G.J. Habgood, L.A. Singer, L.V. DiPietro, Y.Wang, J.J. Chen, D.A. Quincy, A.DavisK. Yoshimatsu, Y. Kishi, M.J. Yu, and B.A. Littlefield, Cancer Res., February 1, 2001; 61(3): 1013-1021

SARActive Fragment

of Halichondrin B

"Simplified" Versionof Active Fragmentis Drug Candidate

E7389

~ 100,000 configurational isomers!

Friedrich Wöhler(1800-1882)

Organic Synthesis has comea long way from urea.

"Perhaps you still remember the experiment I carried out in that fortunate time when I was working with you, in which I found that whenever one tries to react cyanic acid with ammonia a crystalline substance appears which is inert, behaving neither like cyanate nor like ammonia."

To Berzelius (1828)

Thanks&

CreditsT. R. Williams

G. C. Maxfield

P. D. BartlettL. F. Fieser

J. B. Conant

T. W. Richards

W. Ostwald

E. P. Kohler

I. Remsen

R. Fittig

K. Schmid

J. Liebig F. Woehler

J. J. BerzeliusJ. L. Gay-Lussac

C. L. Berthollet “a tall, thin man with a small head, a strong

nose, ice-gray hair, and a thin beard”

Connecticut Science Teachers Association

Good Luck on the Final Exam

Review at Class Time Mondayin 110 SCL

April 29, 2011

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