Kinetic Resolutions - The Stoltz Group

(±)-
Gardiner
(±)-
(±)-
MeO 2C
Ph
Ph
Ph
Ph
CO 2Me
Other Epoxidation Examples with Salen
Catalyst 15
MCPBA, NMO
CH 2Cl 2, -78 o C
Ph
CO 2Me
Ph
H
Ph
O
41% conv., 38% ee, s = 5.2
Anti- compound also in reaction, but no epoxidation of it was observed
(±)-
Matched
(R,R)-15
4 mol% (S,S)- or (R,R)-15
MCPBA, NMO
CH 2Cl 2, -78 o C
Mismatched Matched
(S,S)-15
OR
Ph
O
O
O
Ph
O
O O
O
OR
Mismatched
OR
Ph
Ph
s = 6.3-9.1
CO 2 Me
N N
Mn
t-Bu O Cl O
t-Bu
t-Bu
Ph
O
t-Bu
Catalyst (R,R)-15
Gardiner, et. al., Tet. Lett., 1996, 37(46), 8447
+
CO 2 Me
Linker, Toth, Bringmann, Chem. Eur. J., 1998, 4 (10), 1944
An Alternate Method to Epoxidation KR - Shi
25-75 mol% Catalyst 16
2.3 eq Oxone
9.5 eq K 2CO 3
CH 3CN / DMM
Na 2B 4O 7 in EDTA (aq)
-10 or 0 o C
R = TMS Me COMe CO 2 Et
s = >100 16 39 70
vs.
O
O
OR
O
Ph
O
Ph
O
O O
Favored enantiomer Disfavored enantiomer
+
O
OR
O
O O
Shi, et. al., J. Am. Chem. Soc., 1999, 121, 7718
O
Catalyst 16
O
O
17