EP0721461B1 — Synthesis of 17-(3-pyridyl) steroids

USPTO Abstract

A method of preparing a 3 beta -hydroxy- or 3 beta -(lower acyloxy) 16,17-ene-17-(3-pyridyl)-substituted steroid, wherein the 3 beta -(lower acyloxy) group of the steroid has from 2 to 4 carbon atoms, which comprises subjecting a 3 beta -hydroxy-16,17-ene-17-iodo or -bromo steroid to a palladium complex-catalysed cross-coupling reaction with a (3-pyridyl)-substituted borane in which the pyridine ring is substituted at the 5-position by an alkyl group of 1 to 4 carbon atoms or is unsubstituted thereat, in a proportion of at least 1.0 equivalent of borane per equivalent of steroid, in an organic liquid which is a solvent for the 3 beta -hydroxy steroidal reaction product, and optionally esterifying the resulting 3 beta -hydroxy steroidal reaction product with an esterifying agent effective to replace the hydroxy group by a said lower acyloxy group, which method comprises (a) carrying out the reaction with not more than 1.2 equivalents of borane per equivalent of steroid or (b) crystallising the product of the cross-coupling reaction from a mixture of acetonitrile and methanol.