Studies on Cu-catalyzed asymmetric alkynylation of tetrahydroisoquinoline derivatives

Enantioselective C-C bond formations between the sp(3) C-H bond of prochiral CH2 and terminal alkynes via the cross-dehydrogenative coupling (CDC) reaction were studied. Efficient asymmetric syntheses of alkynyl tetrahydroisoquinoline derivatives were achieved by using a catalytic amount of CuOTf together with PyBox chiral ligand. When dihydroisocluinolinium salts were used as electrophiles, the combination of CuBr/QUINAP provided the best results for asymmetric syntheses of alkynyl tetrahydroisoquinoline derivatives. The factors influencing the enantioselectivity were studied. (c) 2006 Elsevier Ltd All rights reserved.