Abstract
The autoxidation of bisnorcholanic acid, in an acetate buffer (0.2 M, pH 5.0) solution containing acetone and ferrous ions gave six products, A, B, C, D, E, and F ; product D was the major one. Products A and B were those formed by oxy-functionalization at the side chain with successive decarboxylation, and were identified as 20-oxo-5β-pregnane and 20α-hydroxy-5β-pregnane, respectively. Products C and D were ketones having an oxygen function in ring D and were shown to be 15- and 16-oxo-5β-bisnorcholanic acid, respectively. The minor products E and F were assumed to be hydroxylated derivatives of the substrate, which were formed by the introduction of an oxygen function into ring A, B, or C. No autoxidation occurred when the free carboxyl group of the substrate was protected by methylation or reduced to the alcohol.
