Precursor directed regioselective synthesis of partially reduced benzo[e]indene through oxidative cyclization and benzo[h]quinolines

Abstract

We have reported a simple, unprecedented base promoted synthesis of 7-substituted-1-(2-cyano-phenyl/phenyl)-3-sec amino-4,5-dihydro-1H-benz[e]indene-1,2-dicarbonitriles by reaction of 2-oxo-4-sec amino-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles and 2-cyanomethyl-benzonitrile/phenyl-acetonitrile under basic conditions at 100 °C. This reaction involves ring opening of 2-oxo-4-sec amino-5,6-dihydro-2H-benzo[h]chromene-3-carbonitrile by a carbanion generated in situ from 2-cyanomethylbenzonitrile/phenyl-acetonitrile followed by oxidative cyclization to afford the desired product. Alternatively, reaction of 6-aryl-4-sec amino-2H-pyran-2-one-3-carbonitriles and 2-cyanomethyl-benzonitrile under basic conditions provides functionalized benzo[h]quinolines. The structure of the synthesized compound was confirmed by single crystal X-ray.