Palladium-Catalyzed Tandem-Cyclization of Functionalized Ynamides: An Approach to Benzosultams

Abstract

A palladium-catalyzed tandem-cyclization of functionalized ynamides to afford a wide range of hetero-substituted benzosultams (1,2-benzothiazine 1,1-dioxides) has been achieved. Medicinally useful compounds like nortriptyline and eugenol could also be used as nucleophiles. Base has a significant effect in the cyclization process, depending on the nucleophile source used. DFT studies suggest that the reaction involves a [Pd(II)]–[Pd(0)]–[Pd(II)] cycle. Structures of key products were proven by X-ray crystallography. (Figure presented.).