Direct and carbonylative vinylation of steroidal triflates in the presence of homogeneous palladium catalysts
摘要:
The palladium-catalyzed vinylation of several steroid 2-enyl- and 3,5-dienyl-3 triflates and estrone-3-triflate was systematically examined using vinyltributylstannane as a vinylating agent. In carbon monoxide atmosphere the insertion of a CO molecule took place and unsaturated ketones were obtained. In this way new steroid derivatives containing unsaturated side chain were produced which can sei ve as starting material for further functionalization of the steroid skeleton.
Steroidal phenyl ketones were synthesised in high yields by palladium-catalysed carbonylation reactions of 17-iodo-androst-16-ene derivatives in the presence of NaBPh4 under mild reaction conditions. Alkenyl bromides or enol triflates gave lower yields in the same reaction.
ß-aryl and ß-vinyl-αß-didehydro-α-aminoacid derivatives through the palladium-catalysed reaction of aryl and vinyl triflates with methyl α-acetamidoacrylate