Page 22 - Demo-1

Enzymatic Methods - Hydrolysis
Amino acid synthesis
R1
Alcalase R1
pyridoxal 5-phosphate H2N
H2N
CO2R CO2H
t-BuOH/H2O (19:1) P. thiasolinophilum
Lipozyme
Et3N/BuOH Toluene
CO2H
SN
NH2 O
NO
90-98% ee, 87-95% yield
HS CO2H NH2
100% ee, 100% yield
O
OO
(S) - keterolac
Ph
N CO Bu H 2
H2N CO2H L-(S)-tert leucine
Ph
Many other useful hydrolysis systems
99.5% ee, 94% yield
N
CO2Et
S. griseus
buffer pH 9.7
CO2H N
85% ee, 92% yield
OH O
OPO O
NH+
pyridoxal 5-phosphate
OH
Stecher, H.; Faber, K. Synthesis 1997, 1
Enzymatic Methods - Esterifications
DKR of Hemiacetals, cyanohydrins, and derivatives
O RH
MeO
O
Many other esterifications
O
HO H
O
High pH
OH Lipase OAc RX Acyldonor RX
OH
P. cepacia
SiO2
OAc, TBME
OH
X = SR', OR', NHR', CN
OAc
MeO
O
> 95% ee, 63% yield
OH H
SBu
SBu
slow
OH O Conditions: Lipase, vinyl acetate, Et3N
fast
OAc H
AcO H
97% ee, 75% yield
O
Taniguchi, T.; Ogasawara, K. Chem. Commun. 1997, 1399