The novel behaviour of dialkyl phosphites toward 1,4-benzoquinone monoimines

Abstract

Diethyl phosphite 2a reacts with N- (phenylsulfonyl) - 1,4 - benzoquinone monoimine 1a to give 1,4-diethyl [(2-hydroxy-5-[(phenylsulfonyl) amino ] phenyl] [ sphosphonate 3a, diethyl (1-hydroxy -4- [ ( phenylsulfonyl ) imino ] -2,5-cyclohexadiene )] phosphonate 3b and amide 3c , respectively. When quinone monoimine 1a was reacted with dimethyl and diisopropyl phosphites ( 2b,c), the corresonding dialkyl phosphonate adducts (bd3e) and (bd3f) were obtained. Whereas quinone monoimine (bd1b) is reduced mainly to amide (bd4b) when treated with diethyl phosphite (bd2a) , it reacts with dimethyl phosphite (bd2b) to give the dialkyl phosphonate adduct (bd4a) together with amide (bd4b) . Possible reaction mechanism are considered and the structural assignments are based on compatible analytical and spectroscopic results.