Cope rearrangements of arylvinylhydroxylamines

Abstract

Addition of N-arylhydroxamic acids or N-aryl-N-hydroxycarbamates to dimethyl but-2-ynedioate gives N-acyl-N-aryl-O-(1,2-bismethoxycarbonylvinyl)hydroxylamines, which rearrange spontaneously to dimethyl (2-acylaminophenyl)oxalacetates. Addition of O-arylhydroxylamines to dimethyl but-2-ynedioate gives O-aryl-N-(1,2-bismethoxycarbonylvinyl)hydroxylamines, which also rearrange spontaneously and then cyclise to give 3-amino-4-methoxycarbonylcoumarins.