An efficient Rh(III)-catalyzed C-H functionalization of 3-aryl-2H-benzo[e][1,2,4]thiadiazine-1,1-dioxides with diaryl and dialkyl alkynes has been developed for the first time to the synthesis of 1-aminoisoquinoline derivatives in a single step. This method involves through the formation of two C-C bonds and one C-N bond followed by desulfonylation to generate a novel series of isoquinolines in good to excellent yields. This is a direct method to produce pharmaceutically more relevant scaffolds with a high functional diversity.