Exam 4 Solution Key - Organic Chemistry | CH 331, Exams of Organic Chemistry

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Chemistry 331

Organic Chemistry I

Exam 4

Br-^ HOMO H 3 C-Br LUMO

Name ________________________________________________________________

(please print)

Br-

C

H

H

H

Br

1. Give the products for the following two equations (E2 mechanism): (5 points)

H^ Br

H 3 C H

H 3 C H 3 C

CH 3 CH 3

CH 3

(iPr) 2 NH

H^ Br H 3 C^ H

H 3 C

H 3 C H 3 C CH 3 CH^3

(iPr) 2 NH

H 3 C

H 3 C CH 3

H 3 C H 3 C CH 3

H

H 3 C

H 3 C CH 3 H 3 C CH 3 CH^3

H

2. Explain the following reaction. Give a detailed reaction mechanism.

OH

H+

OH

H+

H O+ H

CH+ C+

e)

OH

H 3 C

1. Toluolsulfonylchloride, pyridine
   2. NaI, acetone

I

H 3 C

f) H^3 C^ Br

Br (^) H

2 mol LiSH

DMF

H 3 C SH

HS (^) H

g)

H 2 C

H

OH

H 3 C

CH 3

PBr 3

H 2 C

H

Br

H 3 C

CH 3

h)

CH (^3) SOCl 2 pyridine H 3 C^ OH CH 3

CH 3 H 3 C^ Cl CH 3

i) NH

1. excess CH 3 I
2. Ag 2 O H 3 C

N+ H O -^ CH^3 H^3 C

NH^2 C CH 3

j)

NH

CH 3

CH 3

1. xs CH 3 I 2. Ag 2 O

3. heat

H 3 C

N

CH 2

CH 3

CH 3

4. Indicate how you would carry out each of the following transformations. Besure to include necessary reagents, solvents, and conditions. More than one

step may be necessary. (3 points each)

a)

OH

CH 3

1. TsCl, Py 2. Na+^ C-

CH 3

b)

OH I

1.TsCl, Py 2. NaI, Acetone

c)

OH

OH

HCOOOH, performic acid

d)

Br

Br

Br 2 , CCl 4

j) C^ C

Ph

Br Ph

H

H

Br

C C

Ph

H Ph

H

NaI, Acetone

5. The following reaction works for HBr, however, only with poor yields for HCland HI:

OH

H H

Br

HBr

Give reaction conditions to obtain

a) the chloride ( not HCl!), including mechanism,

b) give reaction conditions and intermediates to obtain the iodide ( Hint: use

c) tosylchloride).Give alternative reaction conditions (not HBr !) to obtain the bromide (

points each).

OH

H H Cl

SOCl 2

OH

H O S

O

H Cl

OH

H H I

1. TsCl, NaI

OH

H H Br

PBr 3

Explain the outcome of the E2-reactions with stereochemical arguments. HINT:

Draw the 6-membered rings as chairs !! (10 points)

CH 3

Br

NaOCH 3 CH^3

H 3 C

H 3 C O

Br O

O

O

H 3 C

O

H 3 C

CH 3

O

O

CH 3 O O CH^3

O

CH 3

KOH

H

Br H

CH 3

H 3 C H

H

H BrH

anti-periplanar

O

Br

H

H

O

O O

O

CH 3

H 3 C

H 3 C

CH 3

anti-periplanar