Sulfoximine and Sulfoxonium Ylide Directed C-H Activation and Domino Cyclization: Construction of Heterocyclic and Carbocyclic Rings

Abstract

The thesis presents the construction of heterocyclic and carbocyclic rings using rhodium-catalyzed C-H bond activation followed by a tandem cyclization strategy. This involves the synthesis of heterocyclic compounds such as 1,2-benzothiazine using sulfoximine directed Rh(III)-catalyzed C-H activation and tandem [4+2] annulation with arylalkynyl silanes. A poly-heterocyclic furanone-fused 1,2-benzothiazine is synthesized using 4-hydroxy-2-alkynoate as a coupling partner using sulfoximine as a directing group by domino C-H activation, [4+2] annulation, and lactonization. The thesis also involves the synthesis of carbocycles such as furanone fused 1-naphthols by Rh(III)-catalyzed domino C-H activation, [4+2] annulation, and followed by lactonization using sulfoxonium ylide as a traceless carbenoid based directing group. In this Rh(III)-catalyzed C-H activation, sulfoxonium ylide is used as a directing group for the synthesis of 3-substituted indonone derivatives, which also involves a tandem [4+1] annulation. In this study, sulfoxonium ylide acts as a traceless directing group and internal oxidant. Therefore, external metal oxidants are not required, and the byproduct obtained is DMSO, which can be easily removed. Sulfoxonium ylide was also used as a directing group for the synthesis of 2H-cyclopropa[b]naphthalen-2-one carbocyclic scaffolds using allylates as coupling partners. This reaction proceeded via domino Rh(III)-catalyzed, [4+2] annulation, and cyclopropanation.