2025 Spring CHEM 0320 Name__________________________
Exam 3 Page 1
I. (38 points) Complete each of the following reaction schemes. Complete structures are required.
Include stereochemistry as appropriate. If stereoisomeric products form, draw one and write
“+enantiomer” or “+diastereomer” In the box.
O O
O NaOCH2CH3
1a. + O + CH3CH2OH
H O HOCH2CH3
ester 5 ketone 5
O O
HO
O O
H3CO H3CO
1) NaH 1) LDA
1b.
2) O 2) I
Cl
OCH3 H3CO
OCH3 Cl OCH3
5 Br “+enantiomer” +1 6
O
O OLi 1) O O
Me2CuLi O CN
1c. O
2) Acidic Workup
5 “+diastereomer” +1 6
1) Li , -78 °C
CH3O O CH3O OH O
O
1d. 2) O
O
Br OCH3 Br OCH3
3) H3O+ workup “+enantiomer” +1 6
, 2025 Spring CHEM 0320 Name__________________________
Exam 3 Page 2
II. (23 points)
2a. Malaria is a major health crisis affecting around 250 million people globally. The following is the start to
the total synthesis of strasseriolide, which is a potent antimalarial agent. Draw the predicted product. You
do not need to show stereochemistry.
O O
N LDA N
I
5
2b. What is the expected stereochemical outcome for the above reaction?
one unique compound
a racemic mixture
circle
one: a pair of 2 diastereomers
a mixture of 3 or more stereoisomers 3
2c. For the following molecule, circle the proton that will be deprotonated when the molecule is treated with
one equivalent of LDA. Briefly explain your answer.
Circle the most acidic proton Explanation
H
H O The conjugate base has the most electron density delocalization by
O resonance stabilization from the allylic diene +3 and carbonyl group +3.
N H
H No credit for only resonance stabilization
H O O H
H 3 6
2d. Draw the structure of (R,E)-5-bromohex-2-enal.
(R,E)-5-bromohex-2-enal
Br
6 carbons +1
aldehyde on C1 +1
alkene on C2 +1
Br on C5 +1
(R) on C5 O
trans alkene +1 6
Exam 3 Page 1
I. (38 points) Complete each of the following reaction schemes. Complete structures are required.
Include stereochemistry as appropriate. If stereoisomeric products form, draw one and write
“+enantiomer” or “+diastereomer” In the box.
O O
O NaOCH2CH3
1a. + O + CH3CH2OH
H O HOCH2CH3
ester 5 ketone 5
O O
HO
O O
H3CO H3CO
1) NaH 1) LDA
1b.
2) O 2) I
Cl
OCH3 H3CO
OCH3 Cl OCH3
5 Br “+enantiomer” +1 6
O
O OLi 1) O O
Me2CuLi O CN
1c. O
2) Acidic Workup
5 “+diastereomer” +1 6
1) Li , -78 °C
CH3O O CH3O OH O
O
1d. 2) O
O
Br OCH3 Br OCH3
3) H3O+ workup “+enantiomer” +1 6
, 2025 Spring CHEM 0320 Name__________________________
Exam 3 Page 2
II. (23 points)
2a. Malaria is a major health crisis affecting around 250 million people globally. The following is the start to
the total synthesis of strasseriolide, which is a potent antimalarial agent. Draw the predicted product. You
do not need to show stereochemistry.
O O
N LDA N
I
5
2b. What is the expected stereochemical outcome for the above reaction?
one unique compound
a racemic mixture
circle
one: a pair of 2 diastereomers
a mixture of 3 or more stereoisomers 3
2c. For the following molecule, circle the proton that will be deprotonated when the molecule is treated with
one equivalent of LDA. Briefly explain your answer.
Circle the most acidic proton Explanation
H
H O The conjugate base has the most electron density delocalization by
O resonance stabilization from the allylic diene +3 and carbonyl group +3.
N H
H No credit for only resonance stabilization
H O O H
H 3 6
2d. Draw the structure of (R,E)-5-bromohex-2-enal.
(R,E)-5-bromohex-2-enal
Br
6 carbons +1
aldehyde on C1 +1
alkene on C2 +1
Br on C5 +1
(R) on C5 O
trans alkene +1 6
