Synthesis of 2-aminoquinoline-3-carboamides and pyrimido[4,5-b]quinolin-4-ones through copper-catalyzed one-pot multicomponent reactions.

Pyrimido[4,5-b]quinolinones have attracted considerable interest from both chemical and medicinal scientists as these compounds display remarkable antimicrobial, anti-inflammatory, antitumor, antiallergy, analgesic, and antioxidant activities. The importance of pyrimido[4,5-b]quinolinones has stimulated enormous efforts to develop efficient methodologies for their synthesis. Herein, we disclose a novel synthetic protocol toward pyrimido[4,5-b]quinolin-4-ones through Cu(OAc)2 -catalyzed one-pot four-component reactions of 2-bromobenzaldehydes, aqueous ammonia, cyanoacetamides and aldehydes. The synthetic procedure combines amination/condensation/cyclization/dehydrogenation reactions in one pot, allowing synthesis of complex compounds in a simple and practical manner. Compared with literature procedures, the synthetic strategies developed herein showed advantages such as readily available and economically sustainable starting materials, structural diversity of products, good functional group tolerance, and a remarkably simple operation process.