Steroidal alkenylphosphonates via palladium-catalyzed coupling reactions

Article abstract of DOI:10.1016/0039-128X(95)00121-6

The palladium-catalyzed coupling of various 17-iodo-Δ¹⁶ steroids (17-iodo-androst-16-ene, 17-iodo-4-methyl-4-aza-androst-16-en-3-one, and 17-iodo-4-aza-androst-16-en-3-one) with dialkyl phosphites (dimethyl phosphite, diethyl phosphite, and diisopropyl phosphite) was examined in detail.The only successful condition for homogeneous coupling involved carrying out the reaction in the absence of any solvents.A large excess of dialkyl phosphite was used, which means that the phosphite itself acted as a solvent.Eight new androst-16-ene derivatives with phosphonate groups at C-17 were synthesized and characterized.These steroids are of pharmacological interest as potential 5α-reductase inhibitors.Under the same conditions, methylation of lactam NH was observed using dimethyl phosphite. - Keywords: coupling reaction of steroids; steroidal alkenylphosphonates; homogeneous palladium(0) catalysts