Specific synthesis of 1-substituted phenothiazines using carbon dioxide protection of the NH group during lithiation

Abstract

The lithiation of phenothiazine when protected as the lithium salt of its carbamate occurs exclusively at the C-1 carbon atom. Reaction of the lithiated species with a variety of electrophiles readily produced several new 1-substituted phenothiazines, as well as a number of known compounds in superior yield to existing methods.