Palladium-catalyzed cyclization of N-n-butyl, N-(o-iodobenzyl)-3-butenamides: six- versus seven- and eight-membered ring formation

Potentially bio-active 2-benzazepine, 2-benzazocine, isoquinoline derivatives were selectively synthesized from N-alkyl, N-(o-iodobenzyl)-3-butenamides and a catalytic amount of palladium complexes. The regiochemistry of the annulation leading to seven/eight- or six-membered ring formation can be completely determined varying medium polarity by the addition of water