Synthesis of [1]benzopyrano[4,3-b]pyrrol-4(1H)-ones from N(α)-(2-Oxo-2H-1-benzopyran-4-yl)Weinreb α-aminoamides

Article abstract of DOI:10.1016/S0040-4020(99)00802-9

N(α)-(2-Oxo-2H-1-benzopyran-4-yl)Weinreb-α-aminoamides were prepared from 4-chlorocoumarin and α-aminoacid derivatives. Their reaction with organometallic compounds (RLi or RMgBr) and subsequent cyclization of ketones thus obtained, give [1]benzopyrano[4,3-b]pyrrol-4(1H)ones. Starting from proline derivatives, simultaneously with the pyranone-pyrrole fusion, we establish an interesting procedure for the formation of pyrrolizines.