Novel Synthesis of Benzothiazole Derivatives via Directed Lithiation and Aryne-Mediated Cyclization Followed by Quenching with Electrophiles

A series of benzothiazole derivatives selectively functionalized at position 7 was synthesized in the course of the following one-pot reaction sequence: directed lithiation of 2,2-dimethyl- N -(3-halophenyl)propanethioamides ( 1, 2 ) or N -(3-halophenyl)- tert -butylthionocarbamates ( 15 − 17 ), cyclization of the aryne intermediate, and quenching of the resulting aryllithium with selected electrophiles.