Nickel-catalyzed hydrocarboxylation of ynamides with CO₂ and H₂O: Observation of unexpected regioselectivity

We describe the nickel-catalyzed hydrocarboxylation of ynamides with CO₂ and H₂O to afford a variety of α-amino-α,β-unsaturated esters with high regioselectivities. The selective α-carboxylation of ynamides with this catalytic protocol is unexpected in view of the electronic bias of ynamides and is in sharp contrast to our previous study in which a stoichiometric amount of Ni(0) was used to form a β-carboxylated product exclusively. We revealed that this unexpected C-C bond formation was induced by the combination of Zn and MgBr₂.