1H-1,3-Benzazaphospholes: The Organometallic Route and a New Three-Step Synthesis with Reductive Ring Closure

Abstract

Primary and N-secondary 2-phosphanylanilines were synthesized via metallation of 2-bromoanilines, coupling with ClP(NMe2)2, alcoholysis and reduction with LiAlH4, and subsequently reacted with formimidoester hydrochloride to give 1,3-benzazaphospholes. For 1H-1,3-benzazaphospholes, a shorter alternative three-step synthesis was developed, based on N-acylation of 2-bromoaniline, NiCl2-catalyzed arylation of triethyl phosphite and a new reductive cyclization of amidophosphonic acid este with excess LiAlH4.