Reactions of carbene intermediates from the reaction of trialkyl phosphites with dialkyl benzoylphosphonates: preparation and reactions of dimethyl 2-(N-tert-butyl-N-methylamino) benzoylphosphonate and dimethyl 2-(methylamino)benzoylphosphonate

Abstract

Dimethyl 2-(methylamino)benzoylphosphonate has been prepared by the thermal decomposition of dimethyl 2-(N-tert-butyl-N-methylamino) benzoylphosphonate formed by the action of triethylamine on 1-tert-butyl-3-(dimethoxyphosphinyl)-1-methyl-2,1- benzisoxazolinium hexafluorophosphate. The reactions of both benzoylphosphonates with trimethyl phosphite proceed via carbene intermediates 4 to initially give ylidic phosphonates 5, which for 5 (X = 2-MeNH) undergoes cyclisation and rearrangement to give the novel 2-oxophosphorindoline 11.