Benzopyrones. Part III. Synthesis and mass spectra of some oxopyranobenzoxazolecarboxylic esters
作者:G. Barker、G. P. Ellis
DOI:10.1039/j39710001482
日期:——
The preparation of ethyl 8-amino-7-hydroxy-4-oxochromen-2-carboxylate (1) and two of its isomers from the corresponding nitro-compounds is described. Cyclization of the Schiffbasesfrom these amino-phenols and various nitrobenzaldehydes gave the oxopyranobenzoxazoles (4)–(7). The amino-phenols (1) and (2) were also cyclized by use of phosgene or thiophosgene to give the corresponding oxo- or thioxo-oxazoles