New 9,10-secosteroids from biotransformations of bile acids with Rhodococcus ruber

Abstract

The biotransformations of cholic, deoxycholic, and hyocholic acids with Rhodococcus ruber are reported. In all biotransformations, the C 17-side chain is partially degraded, and the new 9,10-secosteroids 4a (54%) and 4b (55%) are obtained from cholic and deoxycholic acids, respectively. The loss of H2O from C(11)-C(12) of secosteroids 4a and 4b affords the compounds 5a (5%) and 5b (20%), respectively. On the other hand, in the biotransformation of hyocholic acid with R. ruber the 9,10-secosteroid 4c is not detected, but, rearranging to an intramolecular hemiacetal form, it evolves to the final furan derivative 6c (35%) by easy elimination of two molecules of H2O. The new secosteroids were characterized by IR, NMR, and 2D-NMR spectroscopy, and mass spectroscopy. Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich.