METALS IN ORGANIC SYNTHESES .12. HYDROCARBOALKOXYLATION OF ETHYL 3-BUTENOATE CATALYZED BY PALLADIUM COMPLEXES

The effects of the main reaction parameters on yield and regioselectivity in the hydrocarboalkoxylation of ethyl 3-butenoate, catalyzed by a left bracket PdCl//2(PPh//3)//2 right bracket -PPh//3 system, have been investigated. A higher regioselectivity towards diethyl glutarate is obtained in a polar solvent, such as ethanol, or in the presence of higher concentrations of added PPh//3 or under low carbon monoxide pressure. As a general trend, higher regioselectivity is obtained at the expense of the yield. In ethanol, high yields but low regioselectivities are obtained when the catalyst is employed together with HCl; in benzene the presence of HCl strongly inhibits the catalysis. The palladium catalyst is highly active and regioselective in the presence of SnCl//2.