Estra-1,3,5(10),16-tetraene derivatives represented by the following formula (I):
1
(wherein R
1
represents hydroxy, alkoxy, or NR
2
R (wherein R
2
and R
3
are the same or different, and each represents hydrogen, straight-chain lower alkyl having 1 to 3 carbon atoms, or branched-chain lower alkyl having 3 to 8 carbon atoms)), or pharmaceutically acceptable salts thereof.
Palladium-catalysed carbonylation reactions have been developed in the presence of formic acid as carbon monoxide source. α,β-Unsaturated carboxylic acids and esters were synthesized by the transformation of alkenylhalides in moderate to good yields. The selection of the base proved to be crucial regarding the reaction outcome. A set of various substrates were proven under optimised reaction conditions