Base‐Mediated Synthesis of 1,3‐Diazaphenothiazines from 2‐Methylbenzothiazoliums, Aryl Aldehydes and Amidines.

In this study, we developed a process for the [2+1+3] cyclization of 2‐methylbenzothiazole salts, aldehydes and amidine hydrochlorides, which allows rapid synthesis of 1,3‐diazaphenothiazines with moderate to good yields. The use of ethanol as solvent, oxygen as the terminal oxidant, mild reaction conditions, good functionality tolerance show the promising application in organic synthesis. [ABSTRACT FROM AUTHOR]