Microbiological hydroxylation. Part XX. Hydroxylation of dioxygenated 5α-androstanes with the fungi Absidia regnieri and Syncephelastrum racemosum

Dioxygenated androstanes are readily hydroxylated by the title fungi. Although complex mixtures are generally formed, 3β-hydroxy-5α-androstan-7-one is converted efficiently into its 12α-hydroxy-derivative (51% yield) by S. racemosum. The poor steroid recoveries of incubations involving 3,17-dioxygenated substrates and A. regnieri are improved by using a medium containing cobalt(II) sulphate: under such conditions 3β-hydroxy-5α-androstan-17-one gives 3β,9α-dihydroxy-5α-androstan-17-one in 49% yield.