Stereoselective Synthesis of Steroids with the Heck Reaction

摘要

Steroids present an attractive synthetic goal because of their biological activity and pharmacological applications. Despite the large number of known synthetic methods, there is a continuous demand lor new approaches that are short, generally applicable, and allow access to compounds with novel structures like 1b. We now describe a new strategy based on the synthesis of the B-ring of the steroid structure by a double Heck reaction between (Z)-(2-bromoethenyl)bromobenzene (2b) and the hexahydro-1 H-indene derivative 3, which can be synthe-sized in a few steps from the ketone 4 by an intramolecular Pd-eatalyzed rearrangement of an allyl formate. With this procedure the otherwise difficult trans-annelalion of 3 is achieved in a Stereoselective way.