1988 Volume 36 Issue 10 Pages 3878-3886
The enzymatic hydrogenation of 5'-formylgriseofulvin (3a) with a cell-free system of Streptomyces cinereocrocatus afforded 5'α-hydroxymethylgriseofulvin (4a). The structure of 4a was determined by comparison of the proton nuclear magnetic resonance (1H-NMR) spectrum, mass spectrum (MS), circular dichroism (CD) and ultraviolet (UV) spectrum with those of 5'α- and 5'β-hydroxymethylgriseofulvin (4a and 5a) which were synthesized chemically. The stereochemistry of hydrogenation was unequivocally determined by 270 MHz 1H-NMR analysis of the acetonide (10b) which was derived from the product obtained by the enzymatic conversion of [7'-2H] 5'-formylgriseofulvin (3b)(Chart 3). The results clearly indicated that the 7'-pro-S-hydrogen of 4a originates from the 7'-hydrogen atom of the substrate (3a), and it was further proved that the 5'-βhydrogen of 4a originates from the medium by the use of deuterium oxide.
