Nicht‐dirigierte kreuz‐dehydrierende (Hetero)arylierung von Allyl‐C(sp 3 )‐H‐Bindungen mittels C‐H‐Aktivierung

Native Amide-Directed C(sp3 )-H Amidation Enabled by Electron-Deficient RhIII Catalyst and Electron-Deficient 2-Pyridone Ligand

Trivalent group-9 metal catalysts with a cyclopentadienyl-type ligand (CpM^III ; M=Co, Rh, Ir, Cp=cyclopentadienyl) have been widely used for directed C-H functionalizations, albeit that their application to challenging C(sp³ )-H functionalizations suffers from the limitations of the available directing groups. In this report, we describe directed C(sp³ )-H amidation reactions of simple amide substrates with a variety of substituents. The combination of an electron-deficient Cp^E Rh catalyst (Cp^E =1,3-bis(ethoxycarbonyl)-substituted Cp) and an electron-deficient 2-pyridone ligand is essential for high reactivity.

Chiral Benzothiophene Synthesis via Enantiospecific Coupling of Benzothiophene S-Oxides with Boronic Esters

Benzothiophenes are valuable heterocycles that are widely used in medicines, agrochemicals, and materials science. Herein, we report a general method for the synthesis of enantioenriched 2,3-disubstituted benzothiophenes via a transition-metal-free C2-alkylation of benzothiophenes with boronic esters. The reactions utilize benzothiophene S-oxides in lithiation-borylations to generate intermediate arylboronate complexes, and subsequent Tf₂ O-promoted S-O bond cleavage to trigger a Pummerer-type 1,2-metalate shift, which gives the coupled products with complete enantiospecificity. Primary, secondary and tertiary alkyl boronic esters and aryl boronic esters are successfully coupled with a range of C3-substituted benzothiophenes. Importantly, this transformation does not require the use of C3 directing groups, therefore it overcomes a major limitation of previously developed transition-metal-mediated C2 alkylations of benzothiophenes.

Rhodium(III)-Catalyzed Synthesis of Skipped Enynes via C(sp3 )-H Alkynylation of Terminal Alkenes

The Rh^III -catalyzed allylic C-H alkynylation of non-activated terminal alkenes leads selectively to linear 1,4-enynes at room-temperature. The catalytic system tolerates a wide range of functional groups without competing functionalization at other positions. Similarly, the vinylic C-H alkynylation of α,β- and β,γ- unsaturated amides gives conjugated Z-1,3-enynes and E-enediynes.

Intermolecular, Branch-Selective, and Redox-Neutral Cp*IrIII -Catalyzed Allylic C-H Amidation

Herein, we report the redox-neutral, intermolecular, and highly branch-selective amidation of allylic C-H bonds enabled by Cp*Ir^III catalysis. A variety of readily available carboxylic acids were converted into the corresponding dioxazolones and efficiently coupled with terminal and internal olefins in high yields and selectivities. Mechanistic investigations support the formation of a nucleophilic Ir^III -allyl intermediate rather than the direct insertion of an Ir-nitrenoid species into the allylic C-H bond.