Transition-metal-catalyzed C–H activation followed by oxidative cyclization with unsaturated coupling partners has been a valuable synthetic tool for the multiring molecular scaffolds. This Perspec...

Cp*M-Catalyzed Direct Annulation with Terminal Alkynes and Their Surrogates for the Construction of Multi-Ring Systems

Electrooxidative annulations involving mild transition metal-catalyzed C-H activation have emerged as a transformative strategy for the rapid construction of five- and six-membered heterocycles. In contrast, we herein describe the first electrochemical metal-catalyzed [5+2] cycloadditions to assemble valuable seven-membered benzoxepine skeletons by C-H/O-H activation. The efficient alkyne annulation featured ample substrate scope, using electricity as the only oxidant. Mechanistic studies provided strong support for a rhodium(III/I) regime, involving a benzoxepine-coordinated rhodium(I) sandwich complex as the catalyst resting state, which was re-oxidized to rhodium(III) by anodic oxidation.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1002/ange.202016895

Electrooxidative Rhodium-Catalyzed [5+2] Annulations via C-H/O-H Activations

Ruthenium(II)-Catalyzed C-C/C-N Coupling of 2-Arylquinazolinones with Vinylene Carbonate: Access to Fused Quinazolinones.

A rhodium(III)-catalyzed formal C–H [5 + 1] cyclization of 2-pyrrolyl/indolylanilines with vinylene carbonate has been explored towards the potent assembly of diverse 4-methylpyrrolo[1,2-a]quinoxalines. This established protocol is characterized by an exceedingly simple reaction system, and excellent functional group toleration and yields. Most importantly, entirely distinct from documented [4 + 2] cyclization conversions, herein, the emerging vinylene carbonate firstly presents as a C1 synthon to realize [5 + 1] annulation and shows new chemical reactivity. Biological studies indicate that these prepared products are promising candidates in terms of their antibacterial activity.

RhIII-Catalyzed formal [5 + 1] cyclization of 2-pyrrolyl/indolylanilines using vinylene carbonate as a C1 synthon

The Rh-catalyzed C–H bond activation/annulation provides a new strategy for the synthesis of new frameworks In this review, we summarize the recent research on the Rh-catalyzed cascade arene C–H bond activation/annulation toward diverse heterocyclic compounds The application, scope, limitations and mechanism of these transformations are also discussed

Recent advances in the Rh-catalyzed cascade arene C–H bond activation/annulation toward diverse heterocyclic compounds

Concise Synthesis of Isocoumarins through Rh-Catalyzed Direct Vinylene Annulation: Scope and Mechanistic Insight.

Rhodium-Catalyzed Annulative Coupling of Isothiazoles with Alkynes through N-S Bond Cleavage.

A nondirected dehydrogenative direct alkenylation of simple aromatic compounds with alkenes under rhodium catalysis is described. The site-selectivity is dominantly dictated by the steric bulkiness...

Gen Mihara

Papers

Concise Synthesis of Isocoumarins through Rh-Catalyzed Direct Vinylene Annulation: Scope and Mechanistic Insight.

Rhodium-Catalyzed Annulative Coupling of Isothiazoles with Alkynes through N-S Bond Cleavage.

Nondirected C-H Alkenylation of Arenes with Alkenes under Rhodium Catalysis