B4M1 studymeeting #10 answer Zhai
Pericyclic reaction
1. One step in the synthesis of periplanone B, the chapter-opening molecule, involved anionic oxyCope rearrangement of the following unsaturated alcohol. Draw the product that results after
protonation of the intermediate enolate.
2. Classify each pericyclic reaction as an electrocyclic reaction, cycloaddition, or sigmatropic
rearrangement. Indicate whether the stereochemistry is conrotatory, disrotatory, suprafacial, or
antarafacial.
3. What type of pericyclic reaction is illustrated in each reaction?
4. Draw a stepwise, detailed mechanism for the following reaction.
5. Provide a mechanism for each reaction below and explain stereochemistry if needed.
kinetic product of the reaction
6.Provide a mechanism for each reaction below and explain stereochemistry if needed.
7.Provide a mechanism for each reaction below and explain stereochemistry if needed.
8.Provide a mechanism for each reaction below and explain stereochemistry if needed.
9.Provide a mechanism for each reaction below and explain stereochemistry if needed.
10.Provide a mechanism for each reaction below and explain stereochemistry if needed.
11.Provide a mechanism for each reaction below and explain stereochemistry if needed.
12.Provide a mechanism for each reaction below and explain stereochemistry if needed.
13.Provide a mechanism for each reaction below and explain stereochemistry if needed.
14.Total synthesis
A
C
B
D
E
1）Mechanism of A
Pictet-Spengler reaction
CO2Me
N
CO2Me
N
BnN
BnHN
HO2C
O
CO2H
O
CO2Me
NBn
N
BnN
HO
O
CO2Me
N
CO2H
CO2H
OH2
N
CO2Me
NBn
N
H
CO2Me
NBn
CO2H
CO2H
CH2O2H
（2）Mechanism of B -（1）
Dieckmann condensation
NaH
CO2Me
N
N
Bn
N
CO2Me
CO2Me
N
Bn
H
OH
N
MeOH,PhMe
Bn
O
CO2Me
N
N
Bn
OMe
N
O
O
OMe
OMe
H
N
Bn
N
OH
CO2Me
N
Bn
N
O
CO2Me
（3）Mechanism of C
OH
Bn
N
Bn
N
N
N
MeO
MeO
Me
MeO
OMe
H
MeO
Me
MeO
Bn
N
N
N
N
OMe
H
Bn
N
Bn
N
O
O
O
CO2Me
OMe
MeO
Me
H
（4）Mechanism of D-(2)
Swern oxidation
O
Cl
Cl
Cl
Cl
O
S
O
O
R
O
O
CO2,CO
R
O
S
H
S
Cl
OH
Et3N
H
H
R
O
H
S
R
O
R
SH
（5）Mechanism of E
Knoevenagel pyridine synthesis
O
HN
NH2OH
H
O
OH
OH
HN
O
N OH
O
N OH
N
OH2
OH
N OH2
H
H
N
O
S