Abstract
In order to clarify the stereochemistry of hydrogen loss from C-4 during the enzymatic dehydrogenation the stereospecifically labeled 4-d1-5α-androstane-3, 17-diones (III, VI) were synthesized. Each substrate was incubated with the cell-free extract of Nocardia restrictus and the biotransformation products, androst-4-ene-3, 17-dione and androsta-1, 4-diene-3, 17-dione, were separated. Inspection of their mass and nuclear magnetic resonance spectra revealed that elimination of hydrogen from C-4 in the △4 unsaturation process is stereoselectively β.
