1.
MeO
MeO
PhSH
Br
N
H
Ns
N
K2CO3
O
MTM DMF
Br
N
H
H
N
O
MTM
MeO
Br
S
N
H
O N
O
S
S
O
O
N
O
H
O
O
O
MeO
Br
MeO
O N
O
S
S
O
O
N
O
N
H
Br
N
H
H
N
O
MTM
S
MeO
Br
MeO
N
H
O N
O
S
S
O
O
N
O
S
Br
N
H
NO2
SPh
N
H
O
O
O
O
S
O
1. I2, Ph3P,
imidazole
2.
O
2. KOt-Bu, THF,
OPMB DMSO
H O
OPMB
N
N
H
P
I
I
O
O
OCH3
O
Ph
p
Ph
Ph
I
O
I
Ph
Ph P O
Ph
OPMB
O
O
I
O
H
Ph
OPMB Ph P O
Ph
OPMB
cyclopentadiene
BocNHOH, NaIO4
3.
O
aq MeOH
Boc
rt
O
O
O
O
N
O H O
N
O I O
H
O
O H
N
O
H
I O
O
O
O
Boc
N
H+ transfer
O
O
O
N
O
O
I OH
O
O
H
O
N
O
O
I OH
O
O
H
CO2CH3
Et3SiO
TBDPSO
Cp2Zr(H)Cl;
Me2Zn, L
(20 mol %)
OSiEt3
H
L=
Zr
Si
O
O
Si
N
H
O
O
4.
H Cl
OTBDPS
O
OSiEt3
Ph
Ph
OH
Cp
Zr Cp
Cl
Et3SiO
OTBDPS
(Me)2Zn
O
O
OSiEt3
Si
O
O
Si
Zn
Et3SiO
Cp
Zr Cp
Cl
CO2CH3
Chiral ligand;
Si
O
H
O
"face selective addition to aldehyde"
O
CH3O
O
OTBDPS
O
OTBDPS
OSiEt3
CH3O
Et3SiO
O
OSiEt3
Et3SiO
L-proline
(20 mol %)
I
5.
H
I
O
PhNO, DMSO
O
Ph
N
H
H
99% ee
O
H
O
N
H
O
I
H
O
H
I
N
H
O
O
O
Ph
N
H
H
O
I
H
H
O
N
H
O
I
H
O
H
H
N
O
H+ transfer
I
I
H
O
N
H
O
H
O
N
H
O
O
O
N
O
H
H
O N
H
H H
O
N H
O
O
H
O N
H
H
I
N
H
O
O
O
H
H
H H
O
O
H+ transfer
I
O N
I
H
O N
H
O
H
N
O
chiral environment, with covalently linked chiral catalyst;
one enantiomer of the product is favored over other
H
O
H