CHEM 332: Spring 2014
Recitation Section 4/24/2014
1. Predict the major product with arrow pushing mechanism. Please do not ignore
stereochemistry.
O
O
ethanol
Me
Ph
Me
Ph 3P CHCOCH3
m-CPBA/CHCl 3
Me
O
O
benzene
H
Me
Ph 3P CHCH3
m-CPBA/CHCl 3
2. Complete the following equilibria, show all products. Using your knowledge of pka’s predict
the equilibrium constant for each reaction. In all cases please draw the expected product,
even if the reaction is highly endothermic.
O
Me
Et 3N
H
K eq =
O
LDA
K eq =
O
NaOH
K eq =
3. When cis-2,4-dimethylcyclohexanone is dissolved in aqueous ethanol containing a trace of
NaOH, a misture of cis and trans isomers results. Propose a mechanism for this
isomerization.
O
O
Me
O
Me
trace NaOH
Me
H 2O/EtOH
Me
Me
Me
Mixture of Cis and trans isomer
4. When bromo ketone 1 is treated with potassium tert-butoxide in tert-butyl alcohol at room
temperature, it gives exclusively 5,5-fused bicyclic ketone 2. In contrast, when 1 is treated
with LDA in THF at -72 °C, followed by heating, the product is predominately the 5,7 fused
ketone 3. Write arrow formalism mechanisms for these cycloalkylation reactions and explain
why the different reaction conditions favor different products.
O
Me
Br
1
1. KOt-Bu/
t-BuOH,
25 °C
2. H 2O
O
1. LDA/THF,
- 72 °C
2. Δ
3. Η2Ο
Me
2
O
3
5. Provide simple synthetic routes from cyclohexanone to the following compounds:
O
O
Me
O
Br
D
D
D
D
O
6. Give the expected products for the aldol condensations of
(a) propanal
(b) pentan-3-one