Development of Greener Catalytic Synthetic Methods of Nitrogen-Containing Compounds Using N-Unprotected Ketimines

Herein we report our recent efforts on the greener catalytic synthetic methods of nitrogen containing compounds using N-unprotected ketimines. We found that alkynylation of N-unprotected trifluoromethyl ketimines proceeded in the presence of zinc catalysts, providing the products in good yield with broad functional group tolerance and unique chemoselectivity. Next, we extended the methodology to catalytic stereoselective addition reactions and found that a direct Mannich-type reaction, a Friedel-Crafts-type alkylation reaction, a decarboxylative Mannich-type reaction, and an arylation reaction proceeded in the presence of appropriate metal or organocatalysts to give alpha-tetrasubstituted amines in high yield and stereoselectivity. The detailed scope and some mechanistic insights of these reactions are also presented.