Stereochemistry of Microbial Transformation of (+)- and (—)-2'-Demethoxydehydrogriseofulvin by Streptomyces cinereocrocatus

To elucidate the stereochemistry of microbial hydrogenation of (+)- and (—)-2'-de-methoxydehydrogriseofulvin (1 and 2) by Streptomyces cinereocrocatus NRRL 3443, deu-terated substrates (la, lb, 2a, and 2b) were synthesized from (+)-griseofulvin (9) and subjected to microbial transformation. The 41.41 MHz ²H nuclear magnetic resonance (NMR) and 400 MHz ¹H NMR studies clearly revealed that the microbial hydrogenations of (+)- and ()-2'-demethoxydehydrogriseofulvin (1 and 2) proceed stereospecifically with an anti-addition of hydrogens at the 2' and 3' positions. Further, the microbial transformation of 1 to (+)-2'-demethoxy-2',3'-dihydrodehydrogriseofulvin (5) indicates an isomerization by the microor-ganism of 1 to the enantiomer, (—)-2 '-demethoxydehydrogriseofulvin (2), which is further hydrogenated to afford 5.