Highly Enantioselective Resolution of β-Amino Esters by Candida antarctica Lipase A Immobilized in Mesocellular Foam: Application to Dynamic Kinetic Resolution.

摘要

Candida antarctica lipase A (CALA) immobilized in functional-ized mesocellular foam in the presence of sucrose, followed by lyophilization, led to a dramatic increase in the enantioselec-tivity as well as an improved thermostability of the enzyme. The immobilized lipase was used for kinetic resolution (KR) and dynamic kinetic resolution (DKR) of the β-amino ester, ethyl 3-amino-3-phenylpropanoate. The temperature of optimum activity of CALA shifted from 20-30°C to 80-90°C on immobilization in the MCF. An "enantiomeric ratio" E (E=ν_A/ν_B; ν_A and ν_B are the rate constants for entantiomers A and B) of 69 and a conversion of 43% in 1 h were obtained at 80°C, whereas non-immobilized CALA lost its activity at T≥50°C. The obtained immobilized CALA showed an E value of greater than 500 at 22°C. Combination of the immobilized CALA with a ruthenium complex, acting as a racemization catalyst, allowed for a successful DKR of ethyl 3-amino-3-phenylpropanoate resulting in 85% conversion and 89% ee.