DABCO-mediated decarboxylative cyclization of isatoic anhydride with aroyl/heteroaroyl/alkoylacetonitriles under microwave conditions: Strategy for the synthesis of substituted 4-quinolones

Abstract

An efficient, 1,4-diazabicyclo[2.2.2]octane(DABCO)-mediated decarboxylative cyclization of isatoic anhydrides with active methylene groups namely aroyl/heteroaroyl/alkoylacetonitriles under microwave condition was developed for the synthesis of substituted 4-quinolones. This method utilizes commercially available substrates, occurs under mild conditions, short reaction time, good to excellent yields, easy scale-up, and is compatible with a wide substrate scope. 4-Quinolones (3) obtained by this DABCO-mediated approach were further explored in order to evaluate their synthetic applicability. Initially, 4-quinolone derivatives were efficiently transformed into corresponding 4-Chloro-2-phenyl-quinoline-3-carbonitriles. Further, 2,4-Diphenyl-quinoline-3-carbonitriles were prepared by palladium catalyzed Suzuki-Miyaura cross-coupling of 4-Chloro-2-phenyl-quinoline-3-carbonitrile with aryl boronic acids.