A Simple Synthesis of Pyridine Aminophosphinic Acids and Pyridine Aminophosphine Oxides. The Unusual Cleavage of Pyridylmethyl-( N -benzylamino)-phenylphosphinic Acids and Phosphine Oxides in Acidic Solutions

Abstract

Pyridine aminophosphinic acids were synthesized in reaction of N-(benzyl)-pyridylmethylimines with ethyl phenylphosphinate, in the presence of bromotrimethylsilane. Pyridine aminophosphine oxides were obtained in excellent yields by treatment of the corresponding imines with diphenylphosphine oxide. Among these compounds, the 2-pyridyl and 4-pyridyl derivatives were subject to a simple cleavage in aqueous mineral acid solutions. Products of the cleavages were N-(pyridylmethyl)benzylamines and phenylphosphonic (or diphenylphosphinic) acid, respectively.