Stereoselective hydrogenation on the exocyclic and conjugated double bond of sesquiterpene lactones by Aspergillus versicolor D-1.

Aspergillus versicolor D-1 was employed to convert dehydrocostuslactone (1) and 3-hydroxy-1(10),3,11(13)-guaiatriene-12,6-olide-2-one (5) stereoselectively. The reactions occurring were specific hydrogenation on the exocyclic alpha,beta-double bond of sesquiterpene lactones with excellent conversion. Products were identified by the analysis of their spectra such as UV, IR, MS, (1)H, (13)C NMR, and NOESY, and the structure of one new compound was elucidated. The characteristic of the stereoselective hydrogenation was also discussed and suggested.