Quaternization of 2-(arylamino)aryliminophosphoranes. A route to N,N'-disubstituted 2-aminodiarylamines and unsymmetrically substituted 1-aryl-1,2,5,6-tetrahydro-1,6-benzodiazocines

Abstract

A convenient route leading to variously substituted N-alkyl-N′-aryl-o-phenylenediamine derivatives via quaternization of the imine nitrogen atom of 2-(arylamino)aryliminophosphoranes is presented. The method allows to introduce identical or different alkyl groups onto both nitrogen atoms. The N,N′-bis-allyl derivatives so obtained, after protecting the secondary amine group, easily undergo RCM cyclization providing unsymmetrically substituted 1,2,5,6-tetrahydro-1,6-benzodiazocine systems in high yields.

Direct Reductive Cyclocondensation of the Nitro Group with the Amido Group: Key Role of the Iminophosphorane Intermediate in the Synthesis of 1,4-Dibenzodiazepine Derivatives

“…In our work published in 2014 we found that the reaction of 2-nitrosodiarylamines with PPh 3 proceeded under very mild conditions and that the corresponding iminophosphoranes were formed in very good yields . Because of the presence of ortho arylamino substituent they turned out to be versatile starting materials in the synthesis of nitrogen-containing heterocyclic frameworks, guided mainly by aza-Wittig condensation. , Later we proved that the corresponding iminophosporanes can also be synthesized from 2-nitrodiarylamines, although the reaction requires elevated temperature . The finding prompted us to employ this reaction and the iminophosphoranes so formed for the synthesis of heterocyclic compounds based on 1,4-dibenzodiazepine scaffold.…”