Rh(III)-catalyzed C−H activation and cyclization of sulfoxonium ylide with acrylates leads to an efficient synthesis of indanone derivatives. The reaction proceeds under mild and external metal-oxidant-free conditions. The sulfoxonium ylide acts as a traceless directing group as well as an internal oxidant. (4 + 1) Annulation after C−H activation leads to the formation of a carbocyclic ring, and the byproduct obtained is DMSO, which can be easily separated.

A weakly coordinating carbonyl-directed coupling of allyl alcohols at the C-4 position of indole derivatives under the C−H activation conditions catalyzed by Rh(III) is reported. This results in alkylation at the C-4 position of indole derivatives exclusively. The obtained product forms a tricyclic derivative under aldol reaction conditions, which can be a potential precursor for synthesizing a few alkaloid molecules such as ergot, hapalindole alkaloids, and related heterocyclic compounds.

[4 + 3] annulation of primary and secondary benzamide and cinnamamide derivatives using allyl alcohol as a coupling partner catalyzed by Rh­(III) is reported, where Rh­(III) is playing a dual role of an oxidant and a catalyst for C–H activation. The Rh-catalyst oxidizes allyl alcohol to its carbonyl derivative, and the in situ-generated carbonyl compound reacts with benzamide in the presence of the Rh-catalyst, forming the corresponding alkylated products. Mechanistic studies show that AgSbF6 is also playing a dual role. Apart from being a halide scavenger, AgSbF6 catalyzes the cyclization of the alkylated product, forming the desired lactam. The current method has good synthetic application and is useful for synthesizing a few biologically active compounds that can act as the dopamine D3 receptor ligand, including berberine-like analogues. The deuteration study and control experiments helped us to propose the mechanism.