Rhodium(III)-Catalyzed Regio- and Stereoselective C–H Allylation of Arenes with Vinyl Benzoxazinanones

Vinyl benzoxazinanone was applied as an electrophilic allylating reagent for a series of arenes under redox-neutral Rh­(III) catalysis. This reaction occurs in high efficiency under mild conditions to afford allylarenes bearing a sulfonamide functionality in exclusively <i>E</i>-selectivity. This allylation system combines C–H activation of arenes and scission of an unstrained six-membered ring

Cobalt(III)-Catalyzed Regio- and Stereoselective α‑Fluoroalkenylation of Arenes with <i>gem</i>-Difluorostyrenes

A cobalt­(III)-catalyzed α-fluoroalkenylation of different arenes with readily available <i>gem</i>-difluorostyrenes has been realized under mild and redox-neutral conditions. This reaction occurs via a C–H activation pathway and offers a step-economical access to various 1,2-diaryl-substituted monofluoroalkenes in excellent <i>Z</i> selectivity in moderate to excellent yields

Cobalt(III)- and Rhodium(III)-Catalyzed C–H Amidation and Synthesis of 4‑Quinolones: C–H Activation Assisted by Weakly Coordinating and Functionalizable Enaminone

Cobalt­(III) and rhodium­(III) catalysts exhibited complementary scope in C–H amidation of aryl enaminones. The amidation reactions proceeded with broad scope under the assistance of a weakly coordinating and bifunctional enaminone directing group. The electrophilicity of the enaminone group can be further utilized in subsequent hydrolysis–cyclization reactions to afford NH 4-quinolones in telescoping reactions

Rhodium(III)-Catalyzed Coupling of Arenes with Cyclopropanols via C–H Activation and Ring Opening

Rhodium-catalyzed C–H activation of arenes has been established as an important strategy for the rapid construction of new bonds. On the other hand, ring-opening of readily available cyclopropanols has served as a driving force for the coupling with various nucleophiles and electrophiles. Nevertheless, these two important areas evolved separately, and coupling of arenes with cyclopropanols via C–H activation has been rarely explored. In this work, the oxidative coupling between arenes and cyclopropanols has been realized with high efficiency and selectivity under Rh­(III)-catalysis, providing an efficient route to access β-aryl ketones. Moreover, the C–H bond has been extended to benzylic C–H bonds

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

Rhodium(III)-Catalyzed Acylation of C(sp³)–H Bonds with Cyclopropenones

Rh­(III)-catalyzed activation and acylation of sp³ C–H bonds has been realized with diarylcyclopropenone as an acylating reagent. Both benzylic C–H in 8-methylquinolines and unactivated C–H in 2-alkylpyridines are applicable in this C–H acylation reaction, providing enones in good yields under redox-neutral conditions

Redox-Neutral Couplings between Amides and Alkynes via Cobalt(III)-Catalyzed C–H Activation

C–H activation assisted by a bifunctional directing group has allowed the construction of heterocycles. This is ideally catalyzed by earth-abundant and eco-friendly transition metals. We report Co­(III)-catalyzed redox-neutral coupling between arenes and alkynes using an NH amide as an electrophilic directing group. The redox-neutral C–H activation/coupling afforded quinolines with water as the sole byproduct

Rhodium(III)-Catalyzed Coupling of Arenes with Cyclopropanols via C–H Activation and Ring Opening

Rhodium-catalyzed C–H activation of arenes has been established as an important strategy for the rapid construction of new bonds. On the other hand, ring-opening of readily available cyclopropanols has served as a driving force for the coupling with various nucleophiles and electrophiles. Nevertheless, these two important areas evolved separately, and coupling of arenes with cyclopropanols via C–H activation has been rarely explored. In this work, the oxidative coupling between arenes and cyclopropanols has been realized with high efficiency and selectivity under Rh­(III)-catalysis, providing an efficient route to access β-aryl ketones. Moreover, the C–H bond has been extended to benzylic C–H bonds

Ruthenium- and Rhodium-Catalyzed Chemodivergent Couplings of Ketene Dithioacetals and α‑Diazo Ketones via C–H Activation/Functionalization

Chemodivergent coupling of α-acylketene dithioacetals with diazo compounds has been realized under catalyst control. The Ru­(II)-catalyzed C–H activation occurred at the olefinic position, and 1:2 coupling with α-diazoketoesters leads to furfurylation. In contrast, the Rh­(III)-catalyzed C–H functionalization occurred at both the olefinic and the <i>ortho</i> C­(aryl)–H positions, and [4 + 2] annulation afforded naphthalenones. Synthetic applications have been performed to demonstrate the usefulness of the coupling system

Access to Substituted Propenoic Acids via Rh(III)-Catalyzed C–H Allylation of (Hetero)Arenes with Methyleneoxetanones

An efficient synthesis of disubstituted acrylic acids has been realized via Rh­(III)-catalyzed C–H activation of (hetero)­arenes and coupling with four-membered methyleneoxetanones under redox-neutral conditions. In most cases, the reactions are silver-free, and the products are exclusively <i>E</i>-selective with a broad substrate scope. The transformation proceeds via ortho C–H activation followed by selective olefin insertion and β-oxygen elimination