Synthesis of Pyrido[2, 3‐a]phenoxazines and Pyrido[2, 3‐a]phenothiazines via Successive S_NAr Processes

Abstract

An efficient method was developed for the synthesis of novel pyrido[2, 3-a]phenoxazines and phenothiazines. The base-promoted reaction of 8-chloro-5,7-dinitroquinoline with binucleophiles (o-aminophenols and o-aminothiophenols) results in substitution of the chlorine atom followed by replacement of the nitro group. In case of aminothiophenols the products of in situ Smiles rearrangement were isolated.

Transition-Metal-Free Synthesis of N-Arylphenothiazines through an N- and S-Arylation Sequence

“…Accessible arenes were significantly expanded using a variety of substrates without the activation by electron-withdrawing groups in recent remarkable achievements on concerted S N Ar reactions (Figure B) . We herein present an N - and S -arylation sequence not requiring electron-withdrawing groups to form N -arylphenothiazine scaffold from easily available o- sulfanylanilines (Figure C) . A key point for the facile N -arylphenothiazine synthesis is that the easily introducible ortho arylthio group plays as a masked thiolate and an aryl donor moiety for N -arylation …”