Oxidative coupling of benzylamines with internal alkynes accompanied by dehydrogenation and dehydrogenative cyclization proceeds efficiently under rhodium catalysis to selectively give the corresponding 3,4-substituted isoquinoline derivatives. The procedure is also applicable to the reactions of (1-naphthylmethyl)amine with diaryl- and dialkylacetylenes to construct benzo[h]isoquinoline and benzo[e]isoindole frameworks, respectively.