Niobium- and zirconium-catalyzed reactions of substituted 2 alkynylamines with EtZn.

The NbCl-EtMgBr-catalyzed reaction of ,-disubstituted 2-alkynylamines with EtZn followed by hydrolysis or deuterolysis affords (2)-alkenylamines (reduction products of alkyne) in high yields. The reaction of ,-disubstituted 2-alkynylamines with EtZn catalyzed by the CpZrCl-EtMgBr system occurs as 2-zincoethylzincation, resulting, after deuterolysis or iodinolysis, in the regio- and stereoselective formation of the corresponding dideuterated and diiodinated 2-alkenylamine derivatives with a trisubstituted double bond. This study demonstrates the difference between the catalytic effects of NbCl and CpZrCl on the pathway of reaction of tertiary 2-alkynylamines with EtZn in the presence of catalytic amounts of EtMgBr.