Concise Alkynylation-Amination-Lactamization Synthesis of 4-Aminoquinolin-2(1H)-ones in Two Steps or in a One-pot Fashion

Starting from ortho-iodo anilines, ethyl propiolate, and amines 19 ethyl o-anilino-β-aminoenoates are formed in a consecutive threecomponent Sonogashira alkynylation-Michael addition reaction in moderate to excellent yields (33-86%). These compounds undergo lactamization to 4-aminoquinolin-2(1H)-ones, either in a separate transformation in moderate to excellent yield (13 examples, 27-99%) with AlCl3 as a Lewis acid, or en route in the sense of a Sonogashira alkynylation-Michael addition-lactamization reaction in moderate to good yield (11 examples, 27-68%) in the presence of SnCl4 as a Lewis acid.