Conversion of pimaric acid into cleistanthane derivatives
Abstract
A method for the conversion of pimarenes (a) into cleistanthanes (c)via 4,4-dimethyl-17-nor-5a,13α-androst-8-en-16-one (18) is described. Several unsuccessful attempts to induce the pimarane → cleistanthane rearrangement with pimarane derivatives such as the triol diacetate (7), the diol acetate (8), and the mono-alcohol (17) are also reported.