The Preparation of Benzoisothiazolo[1,2‐b][1,2]isoquinolin‐11‐one‐1,1‐dioxides from Dilithiated ortho‐Toluic Acids and Lithiated Methyl 2‐(Aminosulfonyl)benzoate.

Abstract

Select dilithiated ortho-toluic acids were prepared in excess lithium diisopropylamide and condensed with methyl 2-(aminosulfonyl)benzoate followed by a twofold cyclization of intermediates to afford benzoisothiazolo[1,2-b][1,2]isoquinolin-11-one-1,1-dioxides, a new fused-ring heterocyclic system.