Kinetic Resolutions - The Stoltz Group

(±)-
(±)-
R S
RL
O
R 1
O
R 2
O
R 2
O
25-75 mol% Catalyst 16
O O
O
2.3 eq Oxone
9.5 eq K 2 CO 3
CH 3CN / DMM
Na 2 B 4 O 7 in EDTA (aq)
-20 to 0 o C
R 1
More Shi Epoxidation
R
TMS
1 = Alkyl, OMe, OTBS, OTMS
R 2 = Ph, OPiv,
s = 11-61
vs.
O
R 1
O
O
R 2
O
R 2
O O
Favored enantiomer Disfavored enantiomer
R M
H
R L
RS
H
R S
R L
RM
R M
R S
H R L
OH OH
H
R M
O
+
R 1
R 1
O
R 2
O
O O
Shi, et. al., J. Am. Chem. Soc., 1999, 121, 7718
Alkenes and Allenes - Sharpless Dihydroxylation
Top (!)- attack
Bottom (")- attack
AD-mix
AD-mix contains:
Cinchona alkaloid PHAL ligand
K 2 OsO 2 (OH) 4
K 3 Fe(CN) 6
K 2 CO 3
+
N N
O
O
Catalyst 16
Et
Et
N
N N N
H
O
O
H
MeO OMe
Et
MeO
H
N
N
O
(DHQD) 2PHAL
(In AD-mix-!)
N
N
O
(DHQ) 2 PHAL
(In AD-mix-")
N
N
H
Et
O
OMe
Sharpless, et. al., J. Org. Chem., 1992, 57, 2768
18