Enzymes in Organic Synthesis, 11. Enantioselective Lactonization of Methyl 3,5‐Dihydroxyalkanoates. — An Access to (3 R ,5 S ,6 E )‐3‐Hydroxy‐7‐phenyl‐6‐hepten‐5‐olide by Enzyme‐Catalyzed Kinetic Resolution in Organic Solvents

By enzyme‐catalyzed intramolecular transesterification methyl (±)‐(3 R *,5 S *,6 E )‐3,5‐dihydroxy‐7‐phenyl‐6‐heptenoate ( rac ‐ 4 ) can be enantioselectively converted into the δ‐lactone 5 . An enantiomeric excess of 80% was obtained by Pancreatin in diethyl ether at ambient temperature. Repetition of the enzyme‐catalyzed lactonization with enantiomerically enriched 3,5‐dihydroxy ester 4 / ent ‐ 4 enhanced the e.e. to >99%. Lipases of Pseudomonas and Candida sp. 382 tested in eight organic solvents were less efficient. The absolute configuration of 5 , obtained as the major enantiomer in all experiments, has been determined by its conversion into the known (—)‐goniothalamin ( 6 ).