Dimethylzinc-mediated alkynylation of imines.

The treatment of various aromatic and aliphatic aldimines with a mixture of a terminal alkyne and a commercially available dimethylzinc solution in toluene yields the corresponding protected propargylic amines in moderate to excellent yields. The reaction proceeds in the absence of any activator. These observations led to the development of a three-component synthesis of propargylic amines in which the product was obtained upon mixing an aldehyde with ortho-methoxyaniline and phenylacetylene in the presence of dimethylzinc, through in situ formation of the corresponding imine.