Carbamoylstannation of Terminal Alkynes with Carbamoylstannanes: Catalyst-Dependent Regiochemical Reversal

Rh(acac)(CO) 2 catalyzes addition of ( N, N -diisopropylcarbamoyl)trimethylstannane to terminal alkynes to give ( Z )-β-stannyl-α,β-unsaturated amides with terminal attachment of the amide group, while the use of Ni(cod) 2 results in the reversal of the regioselectivity. A mechanism initiated by the oxidative addition of the carbamoylstannane was proposed on the basis of the isolation of (trimethylstannyl)( N, N -diisopropylcarbamoyl)[1,2-bis(dimethylphosphino)ethane]palladium.