Synthesis and Structure of Aminophosphonates Containing 3,5-Di-Tert-Butyl-4-Hydroxyphenyl and Acetal Groups

The reactions of dialkyl [(3,5-di-tert-butyl-4-oxo-2,5-cyclohexadienyl)methyl]phosphonates with N-nucleophiles (aminoacetaldehyde dimethyl acetal and diethyl [(2,2-dimethoxyethyl)aminomethyl]phosphonate give new aminophosphonates containing the 3,5-di-tert-butyl-4-hydroxyphenyl substituent, in addition to the acetal group. The crystal structure of diethyl {(3,5-di-tert-butyl-4-hydroxyphenyl)[(2,2-dimethoxyethyl)amino]methyl}phosphonate is elucidated. The presence of a chiral carbon atom and prochiral phosphorus atom in the aminophosphonate products is responsible for the complicated pattern in the ¹H NMR spectra, the features of which are discussed.