Molecular basis for enantioselectivity of lipase from Chromobacterium viscosum toward the diesters of 2,3-dihydro-3-(4 '-hydroxyphenyl)-1,1,3-trimethyl-1H-inden-5-ol

2,3-Dihydro-3-(4'-hydroxyphenyl)-1,1,3-trimethyl-1H-inden-5-ol, 1, is a chi ral bisphenol useful for preparation of polymers. Previous screening of com mercial hydrolases identified lipase from Chromobacterium viscosum (CVL) as a highly regio- and enantioselective catalyst for hydrolysis of diesters o f 1. The regioselectivity was greater than or equal to 30:1 favoring the es ter at the 5-position, while the enantioselectivity varied with acyl chain length, showing the highest enantioselectivity (E = 48 +/- 20 S) for the di butanoate eater. In this paper, me use a combination of nonsymmetrical dies ters and computer modeling to identify that the remote ester. group control s the enantioselectivity. First, we prepared nonsymmetrical diesters of (+/ -)-1 using another regioselective, but nonenantioselective, reaction. Lipas e from Candida rugosa (CRL) showed the opposite regioselectivity (> 30:1), allowing removal of the eater at the 4'-position (the remote eater in the C VL-catalyzed reaction). Regioselective hydrolysis of (+/- )-1-dibutanoate ( 150 g) gave (+/-)-1-5-dibutanoate (89 g,71% yield). Acylation gave nonsymme trical diesters that varied at the 4'-position, With no ester at the 4'-pos ition, CVL showed no enantioselectivity, while hindered esters (3,3-dimethy lbutanoate) reacted 20 times more slowly, but retained enantioselectivity ( E = 22). These results indicate that the remote ester group can control the enantioselectivity, Computer modeling confirmed these results and provided molecular details. h model of a phosphonate transition state analogue fit easily in the active site of the open conformation of CVL. A large hydropho bic pocket tilts to one side above the catalytic machinery. The tilt permit s the remote ester at the 4'-position of only the (S)-enantiomer to bind in this pocket. The butanoate eater fits and fills this pocket and shows high enantioselectivity. Both smaller and larger eater groups show low enantios electivity because small ester groups cannot fill this pocket, while longer ester groups extend beyond the pocket. An improved large-scale resolution of 1-dibutanoate with CVL gave (R)-(+)-1-dibutanoate (269 g, 47% yield, 92% ee) and (S)-(-)-1-4' monobutanoate (245 g, 52% yield, 89% ee). Methanolysi s yielded (R)-(+)-1 (169 g, 40% overall yield, > 97% ee) and (S)-(-)-1 (122 g, 36% overall yield, > 96% ee).