MICROBIAL OXYGENATION OF CYCLOHEPTYL-N-PHENYLCARBAMATE AND (+ -)-TRANS-2-FLUOROCYCLOHEPTYL-N-PHENYLCARBAMATE WITH BEAUVERIA-BASSIANA/

The title biotransformation of 1 gave trans-4-hydroxycyclohept-1-yl-ca rbamate (3, 10%, 62% eel, its consecutive ketone 5 (12%) and the racem ic cis-isomer 4 (1.8%). Similarly, the racemic trans-2-fluoro analogue 2 yielded mainly four optically active alcohols 7 (24%,, 82% ee), 8 ( 8%, 16% ee), 9 (4.5%, 52% ee) and 10 (5%, 79% ee) by partial kinetic r esolution. The fluorine substituent near the anchoring electron rich g roup caused a remarkable drop in regio-and diastereoselectivity, but i ncreased the enantioselectivity. Obviously, there is not simply an iso steric substitution of a hydrogen in this position, but the electronic effect by fluorine strongly influences the binding mode. Probably 1 a nd the two enantiomers of 2 can be attached in different geometry to t he active site of the enzyme. (C) 1997 Elsevier Science Ltd.