Dual Role of the Rhodium(III) Catalyst in C-H Activation: [4 + 3] Annulation of Amide with Allylic Alcohols to 7-Membered Lactams.

[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 AgSbF is also playing a dual role.

Sulfoxonium-Ylide-Directed C-H Activation and Tandem (4 + 1) Annulation.

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.

Weak Coordinating Carbonyl-Directed Rhodium(III)-Catalyzed C-H Activation at the C4-Position of Indole with Allyl Alcohols.

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.