Niobium- and zirconium-catalyzed reactions of substituted 2 alkynylamines with Et(2)Zn

The NbCl(5)–EtMgBr-catalyzed reaction of N,N-disubstituted 2-alkynylamines with Et(2)Zn followed by hydrolysis or deuterolysis affords (2Z)-alkenylamines (reduction products of alkyne) in high yields. The reaction of N,N-disubstituted 2-alkynylamines with Et(2)Zn catalyzed by the Cp(2)ZrCl(2)–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(5) and Cp(2)ZrCl(2) on the pathway of reaction of tertiary 2-alkynylamines with Et(2)Zn in the presence of catalytic amounts of EtMgBr.