Chem 140B Fall 2013, Final Examination, Wednesday, 11 October 2013, 242 Galbraith Hall Directions: Answer the questions contained in this examination to the best of your ability and according to the instructions for each question. Partial credit will be awarded where appropriate. Exams completed using pencil will not be eligible for re-grade. If using ink, only black or blue ink is allowed. Using erasable ink will be treated as if pencil was used. This exam was printed in single-sided fashion, so you can use the back of pages for scratch work. IMPORTANT: we will honor answers on the back of a page only if its a mechanism question. Policy on cheating: Molecular model kits are the only aids allowed during these examinations. Using notes, crib, or cheat sheets; using notes written or otherwise printed on clothes, skin, or personal belongs; conversing with other students during the exam; using any electricity-powered device; and/or using books or bound material of any sort are considered forms of cheating, and will be disciplined to the fullest extent of UCSD academic code and procedures. UCSD-issued student ID cards ARE REQUIRED DURING THE EXAMINATION and will be checked for validity DURING the exam. Failure to provide valid ID during an examination will result in a score of zero.

Terms and conditions:

By providing your name, ID number, and signature, you agree to abide by the terms above and also acknowledge that you can read, write, and follow directions in English. Print Name: ID Number: Signature: TA: Christina Matt Ryan none

Degree of Unsaturation Formula: DoU = ( 2C + 2 + N H X ) / 2

Question 1. Draw a structure consistent with the following data. Draw a box around your final answer. 25 points total, no partial credit. Molecular formula: C4H9Cl 1H NMR: 1.04 (d, 6 H) 1.95 (m, 1 H) 3.35 (d, 2 H)

Question 2. Draw a structure consistent with the following data. Draw a box around your final answer. 25 points total, no partial credit. Molecular formula: C8H10 1H NMR: 1.25 (t, 3 H) 2.68 (q, 2 H) 7.23 (m, 5 H)

Question 3. Multiple choice. Please rank the following four compounds according to how quickly they react as dienes in a DielsAlder reaction (assuming the dienophile is the same). You should rank the compounds from most reactive to least reactive. Select the letter that corresponds to the series that has your answer and write this letter in the box provided. 15 points total, all or nothing.

A: 1>2>3>4 G: 2>3>4>1 M: 3>1>2>4 S: 4>1>2>3 B: 1>3>4>2 H: 2>4>1>3 N: 3>2>4>1 T: 4>2>3>1 C: 1>4>2>3 I: 2>1>3>4 O: 3>4>1>2 U: 4>3>1>2 D: 1>2>4>3 J: 2>3>1>4 P: 3>1>4>2 V: 4>1>3>2 E: 1>3>2>4 K: 2>4>3>1 Q: 3>2>1>4 W: 4>2>1>3 F: 1>4>3>2 L: 2>1>4>3 R: 3>4>2>1 X: 4>3>2>1

Your answer:

1 2 3 4

Question 4. Which of the following two compounds is more acidic? Explain your answer in twenty (20) words or less. There is no need for grammatical correctness or full sentences. Answers longer than twenty (20) words will get a score of zero (0). 20 points total, partial credit available.

H H

A B

Question 5. Which of the following can be made selectively (mostly one product formed) by free radical halogenation? Please record your selection in the boxes below the structures. Note: Points will be subtracted for erroneous answers, but you cannot get less than a 0 on this question. You should NOT need all of the boxes! 30 points total, partial credit possible, wrong answers will be penalized to the same extent that correct answers are rewarded.

A B C D

E F G H

Cl Br

Cl Br

Cl BrCl Br

Question 6. Using the curved arrow formalism, provide a mechanism for the following process. Do not omit proton transfers! 54 points total, partial credit possible.

N COOHH2SO4, H2O

Question 7. Using the curved arrow formalism, provide a mechanism for the following process. Do not omit proton transfers! Hint: protonate the double bond to give the more stable cationic species. 21 points possible, partial credit possible.

O O O PhOH

H2SO4,

Question 8. Using the curved arrow formalism, provide a mechanism for the following process. Do not omit proton transfers! 48 points total, partial credit possible.

Li N+then H3O+

O

Question 9. Using the curved arrow formalism, provide a mechanism for the following process. 18 points total, partial credit possible.

OH conc. H2SO4

Question 10. Predict the product. If there is no overall change, write NR (no reaction). Draw a box around your final answer. 24 points total, partial credit possible.

O OHCl,

HOOH

BH3 then NaOH, H2O2

(show productstereochemistry for

full credit)

OH m-CPBA

Cl

OH

NaOH

Question 11. Predict the product. If there is no overall change, write NR (no reaction). Draw a box around your final answer. 24 points total, partial credit possible.

Cl

OH

NaOH

O

OH

SOCl2

O

O

O

AlCl3

OH 3 equiv. Br2,cat. FeBr3

Question 12. Predict the product. If there is no overall change, write NR (no reaction). Draw a box around your final answer. 24 points total, partial credit possible.

O

O

O

O

O

O

O

O

O

O

O

O

PPh3

t-BuOK

Ag2O

EtOH(excess),HCl

DIBAL(excess)

Question 13. Predict the product. If there is no overall change, write NR (no reaction). Draw a box around your final answer. 24 points total, partial credit possible.

O

O

O

O

O

OHCN,

NaOAc

PCC

OH

OH

NaH,CH3I

TsCl, C5H5Nthen NaOCH3

Question 14. Supply reagents for the following reactions. Note that each arrow represents a separate reaction. Dont worry about including any workup steps. 24 points total, partial credit possible.

OH

O

HNBu

Bu

O

NBu

Bu

+

OHO HO

O

(Note: the correct answer(s) have nohalogens or oxygen atoms!)

Question 15. Supply reagents for the following reactions. Note that each arrow represents a separate reaction. Dont worry about including any workup steps. 24 points total, partial credit possible.

CN

O

O

O

O

Cl

O

O

O

OH

OH(Note: ignore potential cyclization.)