Lactones 41. Synthesis and Microbial Hydroxylation of Unsaturated Terpenoid Lactones with p-Menthane Ring Systems

Racemic [(±)-4-isopropyl-1-methyl-7-oxa- cis-bicyclo[4.3.0]non-4-en-8-one] and optically active d,e-unsaturated lactones [(-)-(1 R,6 R)-4-isopropyl-1-methyl-7-oxabicyclo[4.3.0]non-4-en-8-one and (+)-(1 S,6 S)-4-isopropyl-1-methyl-7-oxabicyclo[4.3.0] non-4-en-8-one)] with the p-menthane system were obtained and their odoriferous properties were evaluated. Biotransformations of the racemic lactone with three fungal strains: Absidia cylindrospora AM336, Absidia glauca AM177 and Syncephalastrum racemosum AM105, were carried out. Microbial transformations afforded hydroxylactones with the hydroxy group in the allylic position.