Synthesis of 3-alkylbenzoxazolones from N-alkyl-N-arylhydroxylamines by contiguous O-trichloroacetylation, trichloroacetoxy ortho-shift, and cyclization sequence.

摘要: Benzoxazolone pharmacophore is present in clinical pharmaceuticals, drug candidates, and many compounds having a wide spectrum of biological activities. The methods available for the synthesis benzoxazolones have limited diversity due to problems accessibility air-sensitivity diversely substituted o-aminophenols from which they are generally prepared by cyclocarbonylation with phosgene or its equivalents. paper describes mild method 3-alkylbenzoxazolones easily accessible air-stable nitroarenes. Nitroarenes were converted N-alkyl-N-arylhydroxylamines two steps involving partial reduction arylhydroxylamines followed selective N-alkylation. Treatment trichloroacetyl chloride triethylamine afforded good yields through an uninterrupted three-step sequence O-trichloroacetylation, N→C(ortho) trichloroacetoxy shift, cyclization single pot at ambient temperatures. mild, scope, economical, regioselective. Many sensitive groups like alkyl aryl esters, amide, cyano, carbon-carbon double bond survive reaction.