Synthesis of [1]benzopyrano[4,3-b]pyrrol-4(1H)-ones from 4-chlorocoumarin

Article abstract of DOI:10.1055/s-1994-25459

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]