Synthesis of [1]Benzopyrano[4,3-<i>b</i>]pyrrol-4(1<i>H</i>)-ones from 4-Chlorocoumarin

Abstract

4-N-(Acylmethyl)aminocoumarins or their ketal derivatives were prepared from 4-chlorocoumarin and α-amino ketones (chlorohydrates or ketal derivatives) in ethanol/triethylamine media. Their subsequent treatment in acidic or basic media readily led to [1] benzopyrano[4,3-b] pyrrol-4(1H)-ones.