Palladium-Catalyzed Double Carbopalladation/ syn -Insertion Cascade toward a Pragmatic Synthesis of Aminated Polyheterocyclic 1,2-Benzothiazepine 1-Oxides

A palladium-catalyzed tandem cyclization reaction was de-veloped, which offers a pragmatic synthesis of aminated tetracyclic 1,2-benzothiazepine 1-oxides bearing a highly fused medium-sized cyclic unit. An acetyl (Ac) group was found to be the optimal protecting group for sulfoximines to reduce the nucleophilic ability of the N atom, thus efficiently suppressing the formation of intramolecular 5-exo-dig cy-clization side products. The transformation proceeds through a double syn-carbopalladation/annulation sequence to construct the rigid tetra-cyclic carbo-heterocyclic framework with excellent chemoselectivity and regioselectivity.

Automated summary

A palladium-catalyzed tandem cyclization reaction was developed to synthesize aminated tetracyclic 1,2-benzothiazepine 1-oxides with a highly fused cyclic unit. The use of an acetyl group as the protecting group for sulfoximines effectively suppressed the formation of intramolecular cyclization side products, resulting in excellent chemoselectivity and regioselectivity.