Formal Gold- and Rhodium-Catalyzed Regiodivergent C–H Alkynylation of 2‑Pyridones

Formal regiodivergent C–H alkynylation of 2-pyridones bearing different <i>N</i>-substituents has been realized under Au­(I) and Rh­(III) catalysis using a hypervalent iodine alkyne reagent. When catalyzed by Au­(I), the alkynylation occurred at the most electron-rich 5-position via an electrophilic alkynylation pathway. The selectivity was switched to the 6-position under assistance of an <i>N</i>-chelation group when a Rh­(III) catalyst was employed. A rhodacylic complex has been isolated as a key intermediate

Iridium(III)-Catalyzed Synthesis of Benzimidazoles via C–H Activation and Amidation of Aniline Derivatives

Ir­(III)-catalyzed synthesis of benzimidazoles has been realized under redox-neutral conditions by annulation of aniline derivatives with dioxazolones. The reaction proceeded via a C–H activation–amidation–cyclization pathway with a decent substrate scope

Access to Quaternary Stereogenic Centers via Rhodium(III)-Catalyzed Annulations between 2‑Phenylindoles and Ketenes

Rh­(III)-catalyzed C–H activation of arenes and mild oxidative [4 + 2] annulative coupling with ketenes have been realized. The uniquely high reactivity of the C(3) of 2-phenylindoles was successfully utilized to facilitate the reductive elimination process, leading to efficient synthesis of cyclic products with a quaternary carbon stereocenter

Divergent Access to 1‑Naphthols and Isocoumarins via Rh(III)-Catalyzed C–H Activation Assisted by Phosphonium Ylide

Rh-catalyzed C–H activation of phenacyl phosphoniums in coupling with α-diazocarbonyl compounds has been realized with the assistance of a mutifunctional phosphonium ylidic directing group, providing expedient accesses to 1-naphthols and isocoumarins. Switchable synthesis of 1-naphthols and isocoumarins was realized by substrate control, where these transformations were enabled by initial C–H activation and subsequent intramolecular Wittig reaction or nucleophilic C–O formation

Rhodium-Catalyzed Site-Selective Coupling of Indoles with Diazo Esters: C4-Alkylation versus C2-Annulation

A Rh­(III)-catalyzed site-selective C–H activation of C(3)-functionalized indoles in a coupling with diazo esters has been realized with carbonyl as a weakly coordinating group. The coupling selectivity is dictated by the temperature and additives, affording either C4-alkylated indoles or C2-annulated lactones in moderate to excellent efficiency

Regio- and Diastereoselective Access to Fused Isoxazolidines via Ru(II)-Catalyzed C–H Activation of Nitrones and Coupling with Perfluoroalkylolefins

The synthsis of fluorinated isoxazolidines in bicyclic settings has been realized via Ru­(II)-catalyzed C–H activation of aryl nitrones with perfluoroalkyl-substituted olefins as the coupling partner. The reaction proceeded via initial chelation-assisted C­(aryl)–H allylation followed by regio- and diastereoselective intramolecular dipolar addition between the nitrone directing group and the olefin unit

Rh(III)-Catalyzed C–C/C–N Coupling of Imidates with α‑Diazo Imidamide: Synthesis of Isoquinoline-Fused Indoles

Imidate esters and diazo compounds have been established as bifunctional substrates for the construction of biologically active fused heterocycles via rhodium-catalyzed C–H activation and C–C/C–N coupling. This reaction occurs under mild conditions with high efficiency, step economy, and low catalyst loading

Rh(III)-Catalyzed C–C/C–N Coupling of Imidates with α‑Diazo Imidamide: Synthesis of Isoquinoline-Fused Indoles

Imidate esters and diazo compounds have been established as bifunctional substrates for the construction of biologically active fused heterocycles via rhodium-catalyzed C–H activation and C–C/C–N coupling. This reaction occurs under mild conditions with high efficiency, step economy, and low catalyst loading

Rh(III)-Catalyzed Diastereodivergent Spiroannulation of Cyclic Imines with Activated Alkenes

Rh­(III)-catalyzed [3 + 2] annulation of cyclic <i>N</i>-sulfonyl or <i>N</i>-acyl ketimines with activated alkenes has been realized, leading to the synthesis of spirocycles with three continuous stereogenic centers. This atom-economic reaction proceeded efficiently under mild and redox-neutral conditions via a C–H activation pathway, and the coupling is diastereodivergent, with the diastereoselectivity being controlled by silver additives

Rh(III)-Catalyzed Diastereodivergent Spiroannulation of Cyclic Imines with Activated Alkenes

Rh­(III)-catalyzed [3 + 2] annulation of cyclic <i>N</i>-sulfonyl or <i>N</i>-acyl ketimines with activated alkenes has been realized, leading to the synthesis of spirocycles with three continuous stereogenic centers. This atom-economic reaction proceeded efficiently under mild and redox-neutral conditions via a C–H activation pathway, and the coupling is diastereodivergent, with the diastereoselectivity being controlled by silver additives