A copper(I)-catalyzed tandemreaction of 2-bromoaryl ketones, terminal alkynes, and CH3CN is developed, which combines N atom transfer and three-component [3 + 2 + 1] cyclization, and efficiently produces densely functionalized isoquinolines in a facile, highlyselective, and general manner. In the reaction, the formation of aromatic C–N bonds along with the complete C–N triple bond cleavage is first