Facile synthesis of 17-formyl steroids via palladium-catalyzed homogeneous carbonylation reaction

17-Formyl-androst-16-ene and its analogues were synthesized from the corresponding 17-iodo-16-ene derivatives in palladium-catalyzed formylation reaction using tributyltin hydride as hydrogen source under mild reaction conditions. The formation of androst-16-ene and its isomerization products, as well as that of analogous steroidal olefins as side-products, was found to be dependant on the reaction conditions. The formylation reaction tolerates various functional groups on the A and B rings of the steroids.