Microbiological hydroxylation. Part XXII. Hydroxylation of 3,20-, 7,20-, and 11,20-dioxygenated 5α-pregnanes

Abstract

Eight 3,20-, 7,20-, and 11,20-dioxygenated 5α-pregnanes have been incubated with the fungi Calonectria decora and Daedalea rufescens, and with three Rhizopus species. In most cases complex mixtures are formed, and the hydroxylations are less satisfactory than those of dioxygenated androstane analogues. Although Rhizopus nigricans leads mainly to the 11α-hydroxylation of 5α-pregnane-3,20-dione, hydroxylation of 3β-hydroxy-5α-pregnan-20-one occurs predominantly at the 7β-position (not at the 11α-position as reported in the literature). The cleanest incubation studied here is that of 5α-pregnane-7,20-dione with Calonectria decora, which gives the 1α,12β-dihydroxy-7,20-dione (30%) and the 12β-hydroxy-1,7,20-trione (19%).

Convenient preparations of the 7,20- and 11,20-dioxygenated substrates have been developed.