Rh(III)-Catalyzed Asymmetric Synthesis of Axially Chiral Biindolyls by Merging C–H Activation and Nucleophilic Cyclization

Enantiomeric access to pentatomic biaryls is challenging due to their relatively low rotational barrier. Reported herein is the mild and highly enantioselective synthesis of 2,3′-biindolyls via underexplored integration of C–H activation and alkyne cyclization using a unified chiral Rh­(III) catalyst. The reaction proceeded via initial C–H activation followed by alkyne cyclization. A chiral rhodacyclic intermediate has been isolated from stoichiometric C–H activation, which offers direct mechanistic insight

Copper-Catalyzed Hydroamination of <i>gem</i>-Difluoroalkenes Access to Diversified α‑Difluoromethyl Amines

The difluoromethyl group (CF2H) is of great importance in medicinal chemistry. We report herein an efficient method for the synthesis of diversified α-difluoromethyl amines through copper-catalyzed hydroamination of gem-difluoroalkenes, where the C–N bond formed via a α-CF2H transition-metal intermediate. This new reaction proceeds through Cu–H insertion to gem-difluoroalkenes and gives valuable alkyl–CF2H-containing compounds, which overcome the much more challenged β-F elimination from α-fluoroalkyl organocopper species. The reaction exhibits broad substrate scope with readily available starting materials and commercial catalysis

Rh(III)-Catalyzed Asymmetric Synthesis of Axially Chiral Biindolyls by Merging C–H Activation and Nucleophilic Cyclization

Enantiomeric access to pentatomic biaryls is challenging due to their relatively low rotational barrier. Reported herein is the mild and highly enantioselective synthesis of 2,3′-biindolyls via underexplored integration of C–H activation and alkyne cyclization using a unified chiral Rh­(III) catalyst. The reaction proceeded via initial C–H activation followed by alkyne cyclization. A chiral rhodacyclic intermediate has been isolated from stoichiometric C–H activation, which offers direct mechanistic insight

Ag(I)-Catalyzed Nucleophilic Addition and Friedel–Crafts Alkylation between α‑Oxoketene Dithioacetals and Propargyl Carbonates

Silver-catalyzed nucleophilic addition and intramolecular Friedel–Crafts alkylation between α-oxoketene dithioacetals and tertiary propargylic carbonates have been realized. The reactions proceeded in moderate to good yields with broad substrate scope, providing a straightforward method for the synthesis of substituted indenes

Chemodivergent Oxidative Annulation of Benzamides and Enynes via 1,4-Rhodium Migration

Chemodivergent annulative couplings have been realized between N-methoxy benzamides and 1,3-enynes via Rh-catalyzed C–H activation and 1,4-Rh migration. Under Rh/copper catalyzed aerobic conditions, the nitrogen annulation occurred as the major pathway. The chemoselectivity was switched to the oxygen annulation under proper condition control with stoichiometric amounts of Cu­(II) oxidant and NaOAc. Both coupling systems proceeded with a broad scope and functional group tolerance

Divergent Annulative C–C Coupling of Indoles Initiated by Manganese-Catalyzed C–H Activation

Manganese­(I)-catalyzed C–H activation of indoles and divergent annulative coupling with alkyne-tethered cyclohexadienones has been realized under operationally simple conditions. These annulation systems are under condition control. The coupling in the presence of BPh3 additive followed a C–H activation-alkyne insertion-Michael addition pathway, affording an exocyclic olefin attached to a tetrahydrofuran ring. In contrast, when Zn­(OAc)2/PivOH additives were introduced, initial olefination en route to intramolecular Diels–Alder reaction and subsequent elimination of an alcohol was followed to deliver a fused six-membered ring. The selectivity stands in contrast to those reported using rhodium­(III) and cobalt­(III) catalysts, highlighting the unique reactivity and selectivity of manganese catalysts

Rh(III)-Catalyzed Mild Coupling of Nitrones and Azomethine Imines with Alkylidenecyclopropanes via C–H Activation: Facile Access to Bridged Cycles

Bridged cycles are an important class of structural motif in various biologically active molecules. Rh­(III)-catalyzed C–H activation of nitrones and azomethine imines in the context of dipolar addition with alkylidenecyclopropanes (ACPs) have been realized. By taking advantage of the ring strain in ACPs, the reaction with aryl nitrones delivered bridged [3.2.1] bicyclic isoxazolidines, and reaction with azomethine imines afforded bridged tricyclic pyrazolones under the same conditions, where both the nitrone and azomethine imine act as a dipolar directing group. All the reactions occurred under mild conditions with broad substrates scope, high efficiency, and >20:1 diastereoselectivity. The synthetic applications of this protocol have also been demonstrated

Rh(III)-Catalyzed Mild Coupling of Nitrones and Azomethine Imines with Alkylidenecyclopropanes via C–H Activation: Facile Access to Bridged Cycles

Bridged cycles are an important class of structural motif in various biologically active molecules. Rh­(III)-catalyzed C–H activation of nitrones and azomethine imines in the context of dipolar addition with alkylidenecyclopropanes (ACPs) have been realized. By taking advantage of the ring strain in ACPs, the reaction with aryl nitrones delivered bridged [3.2.1] bicyclic isoxazolidines, and reaction with azomethine imines afforded bridged tricyclic pyrazolones under the same conditions, where both the nitrone and azomethine imine act as a dipolar directing group. All the reactions occurred under mild conditions with broad substrates scope, high efficiency, and >20:1 diastereoselectivity. The synthetic applications of this protocol have also been demonstrated