key
Name ___________________
Chem 331
Exam #2
Friday, October 19, 2007
This is an open-book, open notes exam. Please show your work in detail.
1. (20 points) Draw the structures of B and C, and give IUPAC names for A, B, and C. You do not have to
show mechanisms, but you do need to show stereochemistry clearly.
PBr3
OH
B
Mg;
C7H13Br
CH3CN
C
C9H16O
A
(1S, 3S)-3-methylcyclohexanol
Br
O
(1R, 3S)-1-bromo-3-methylcyclohexane
1-((1R, 3S)-3-methylcyclohexyl)ethanone
2. (20 points) Indicate the expected major product. Explain your reasoning in detail.
O
Br
1.
ONa
O
O
2. KOH
Br
O
HO
O
benzylic Br more reactive
O
O
O
O
Br
O
O
O
O
O
inverted
Br
same
O
inverted
3. (20 points) Outline the synthesis steps to convert D into E. In addition to D, you may use any piece
that contributes three or fewer carbons to the final product.
HO
D
CrO3
O
TsCl, pyridine
MgCl
MCPBA
TsO
CH3MgBr
O
OH
4. (20 points) Deduce the stucture of F, and draw an arrow-pushing mechanism for the transformation.
H+
O
H+
13C
C9H10O
H
O
CH3
OH
H
CH3
1H
NMR
14.6, q
53.0, d
127.5, d
128.3, d (2)
129.0, d (2)
137.8, s
200.8, d
F
H3C
NMR
1.42, d, J = 7.3 Hz, 3H
3.63, dq, J = 4.2, 7.3 Hz, 1H
7.22, dd, J = 8.1, 2.4 Hz, 2H
7.31, dd, J = 8.1, 8.2 Hz, 2H
7.38, td, J = 8.2, 2.4 Hz, 1 H
9.65, d, J = 4.2 Hz, 1H
H3C
H
O
H
H
O
F
5. (20 points) Draw a detailed arrow-pushing mechanism for the following transformation. 5/20 points
for correctly showing the mapping of the starting material onto the product.
b
a
c
CO2CH3 +
d
S
e
f
O f
O
O eO
f
O
DMSO
CO2CH3
O
S
O
CO2CH3
O
CO2CH3
O
O
O
S
S
O
CO2CH3 H+
O
O
CO2CH3
O
O
transfer
S
S
O
d CO2CH3
S
O
O
O
O
bb
bf
O-e
a-d
f-H
f-S
a-f
e-f
O-f
d-H
c
+
S
O
b
a