Kinetic Resolutions - The Stoltz Group

Sharpless
Et
t-Bu
Proposed Asymmetric Dihydroxylation Mechanisms
O
O
Os
O
O
L*
O O
O Os
O
N
N
R
O
R = Ph, s = 9.7
R = CO 2Et, s = 32
R
R
N
[2+2]
N
O
N
Et
Sharpless, J. Am. Chem. Soc., 1993, 115, 7864
OAc
R 1
R = Me, 80% conv., 95% ee
N
R = Ph, 70% conv., >98% ee
Alkene: 47% Yield
Ph Ph
>99% ee
Diol: 40% conv.
>95% ee
s = 51.1
O
O
Os
O
O
L*
[3+2]
R 2
OAc
Ph
Corey
N
Et
O
O
Os
O
O
L*
OMe
R
O
H Os O
O N
N
O
O
Resolution of Alkenes Via AD
(unreactive)
Gardiner, et. al., Chem. Comm., 1996, 2709
R = Me, 90% conv., >98% ee
R = Ph, 90% conv., 33% ee
MeO
R
H
N
O
N
Corey, et. al., J. Am. Chem. Soc., 1995, 117, 10827
Sharpless, et. al., J. Am. Chem. Soc., 1996, 118, 35
C 8 H 17
OAc
O R
O
R = Me, s = 3.1
R = Ph, s = 1.6
O
O O
With modified chiral ligand
N
Ph
(anthryl instead of quinuclidine)
R = Me, s = 20
R = Ph, s = 79
25-30% Yield
95-98% ee
Corey, et. al., J. Am. Chem. Soc., 1995, 117, 10827
Ph
Jefford, et. al., Tet. Lett., 1994, 35, 6275
90% conv., >98% ee
Lohray, et. al., Tet. Asym., 1992, 3(11), 1317
19