Synthesis of 2-(2-hydroxyaryl)alkenylphosphonium salts from phosphine oxides via ring-closing ring-opening approach and their antimicrobial evaluation

Abstract

A new two-step synthesis of phosphonium salts from phosphine oxides using Grignard reagents is reported. This approach involves a cyclization of Z-dialkyl-(diaryl)[2-(5-chloro-2-hydroxyphenyl)-2-phenylvinyl]phosphine oxides under the action of sulfinyl chloride with the formation of 2,2-dialkyl(diaryl)-6-chloro-4-phenyl-2H-1,2-benzoxaphosphinin-2-ium chlorides followed by ring opening under the action of organomagnesium compounds. The method was successfully applied to prepare a series of a new phosphonium salts bearing phenolic moiety with a wide range of substituents at phosphorus atom. Synthesized phosphonium salts shows high antibacterial and antifungal in vitro activity and low toxicity towards human red blood cell.