Copper-Catalyzed Diversity-Oriented Three- and FiveComponent Synthesis of Mono-and Dipropargylic Amines via Coupling of Alkynes, a-Amino Esters and Aldehydes

Mono- as well as dipropargylic amines were synthesized using -amino esters as inexpensive building blocks under a single catalytic system (copper bromide, 100 degrees C, 4h, toluene) where the reactant ratio (1a/2a/3a) acted as product specific switch. Both secondary (mono) as well as tertiary (di) propargylic amines formed via three- and five-component coupling exhibited wide substrate scope with moderate to good yields and satisfactory diastereoselectivity in a few cases. The practical utility of the method is enhanced by providing a facile access to enantiopure propargylic amines via lipase-catalyzed resolution along with synthesis of unsymmetrical dipropargylic amines, secondary propargylic amines bearing quaternary carbon centers and imidazolidin-2-ones.