摘要:
Sixteen homologous (5R*,6S*)-6-hydroxyalkan-5-olides rac-5 and their acetoxy derivatives rac-6 were synthesized from the corresponding methyl (Z)-alk-5-enoates 3 by osmium(VIII) oxide catalyzed cis-hydroxylation to the dihydroxy esters rac-4 and hydrolysis of these esters followed by lactonization. Pancreatin-catalyzed lactonization of the dihydroxy esters rac-4 afforded enantiomerically enriched hydroxy lactones ent-5, five of which were obtained enantiomerically pure by recrystallization. Acetylation of the 6-hydroxyalkan-5-olides rac-5 by vinyl acetate catalyzed by the lipase SP 526 provided enantiomerically enriched 6-acetoxyalkan-5-olides 6 with an enantiomeric excess of more than 90% in nine cases. These compounds are known as mosquito oviposition attractant pheromone (6h) or its homologues.