Pybox ligand-promoted copper(I)-catalyzed three-component tandem coupling-annulation of terminal alkynes, amines and ortho-alkynylaryl aldehydes

Pybox ligand was utilized to promote a highly efficient, one-pot, copper(I)-catalyzed three-component tandem addition and cyclization of ortho-alkynylaryl aldehydes, primary amines, and terminal alkynes. Dihydroisoquinoline derivatives 2 were achieved with excellent to moderate yields. In some examples, water was found as an additive to activate the reaction with or without Pybox ligand. Compared with the reported methods, in which imine had to be pre-prepared and purified, the novel process provides a greener choice. (C) 2009 Elsevier Ltd. All rights reserved.