Rhodium(III)-Catalyzed Alkenyl C-H Functionalization to Dienes and Allenes

Diversity-Oriented Synthesis of Indole-Fused Polycyclic Scaffolds via Rhodium-Catalyzed NH-Indole-Directed C-H Coupling of 2-Phenyl-1H-indoles with Propargylic Alcohol Derivatives

Diversity-oriented synthesis strategy for the efficient assembly of indole-fused polycyclic scaffolds via rhodium-catalyzed NH-indole-directed C-H coupling with propargylic alcohol derivatives in a regioselective manner was developed. Five 2-phenyl-1H-indole-embedded core skeletons were synthesized. In particular, three different indole-fused exo-olefin-containing polycycles were realized, which may be manipulated for further chemistry.

Mechanistic Insights Into the Rhodium-Catalyzed C-H Alkenylation/Directing Group Migration and [3+2] Annulation: A DFT Study

The mechanism of the rhodium-catalyzed C-H alkenylation/directing group migration and [3+2] annulation of N-aminocarbonylindoles with 1,3-diynes has been investigated with DFT calculations. On the basis of mechanistic studies, we mainly focus on the regioselectivity of 1,3-diyne inserting into the Rh-C bond and the N-aminocarbonyl directing group migration involved in the reactions. Our theoretical study uncovers that the directing group migration undergoes a stepwise β-N elimination and isocyanate reinsertion process. As studied in this work, this finding is also applicable to other relevant reactions. Additionally, the role of Na⁺ versus Cs⁺ involved in the [3+2] cyclization reaction is also probed.

Recent Advances in Alkenyl sp2 C-H and C-F Bond Functionalizations: Scope, Mechanism, and Applications

Alkenes and their derivatives are featured widely in a variety of natural products, pharmaceuticals, and advanced materials. Significant efforts have been made toward the development of new and practical methods to access this important class of compounds by selectively activating the alkenyl C(sp²)-H bonds in recent years. In this comprehensive review, we describe the state-of-the-art strategies for the direct functionalization of alkenyl sp² C-H and C-F bonds until June 2022. Moreover, metal-free, photoredox, and electrochemical strategies are also covered. For clarity, this review has been divided into two parts; the first part focuses on currently available alkenyl sp² C-H functionalization methods using different alkene derivatives as the starting materials, and the second part describes the alkenyl sp² C-F bond functionalization using easily accessible gem-difluoroalkenes as the starting material. This review includes the scope, limitations, mechanistic studies, stereoselective control (using directing groups as well as metal-migration strategies), and their applications to complex molecule synthesis where appropriate. Overall, this comprehensive review aims to document the considerable advancements, current status, and emerging work by critically summarizing the contributions of researchers working in this fascinating area and is expected to stimulate novel, innovative, and broadly applicable strategies for alkenyl sp² C-H and C-F bond functionalizations in the coming years.

Transition metal-catalyzed double Cvinyl-H bond activation: synthesis of conjugated dienes

Conjugated dienes have occupied a pivotal position in the field of synthetic organic chemistry and medicinal chemistry. They act as important synthons for the synthesis of various biologically important molecules and therefore, gain tremendous attention worldwide. A wide range of synthetic routes to access these versatile molecules have been developed in the past decades. Transition metal-catalyzed cross-dehydrogenative coupling (CDC) has emerged as one of the utmost front-line research areas in current synthetic organic chemistry due to its high atom economy, efficiency, and viability. In this review, an up-to-date summary including scope, limitations, mechanistic studies, stereoselectivities, and synthetic applications of transition metal-catalyzed double C_vinyl-H bond activation for the synthesis of conjugated dienes has been reported since 2013. The literature reports mentioned in this review have been classified into three different categories, i.e. (a) C_vinyl-C_vinyl bond formation via oxidative homo-coupling of terminal alkenes; (b) C_vinyl-C_vinyl bond formation via non-directed oxidative cross-coupling of linear/cyclic alkenes and terminal/internal alkenes, and (c) C_vinyl-C_vinyl bond formation via oxidative cross-coupling of directing group bearing alkenes and terminal/internal alkenes. Overall, this review aims to provide a concise overview of the current status of the considerable development in this field and is expected to stimulate further innovation and research in the future.

RhIII-Catalyzed heteroarylation of N-2,6-difluorophenyl arylamides with heteroaryl boronate esters

An efficient strategy to aryl-heteroaryl formation via RhIII-catalyzed C–H heteroarylation of arenes with N-heterocyclic boronates has been disclosed.

Recent advances in rhodium-catalysed cross-dehydrogenative-coupling between two C(sp2)-H bonds

Rhodium-catalysed cross-dehydrogenative coupling (CDC) has received considerable attention in recent years. This modern technology has been considered as an attractive synthetic tool for selective C−C bond formation due to (1)...

The synthesis of aryl-heteroaryl derivatives via the RhIII-catalyzed heteroarylation of arenes and heteroaromatic boronates

An efficient Rh^III-catalyzed strategy for constructing aryl-heteroaryl derivatives with removable ketoxime ether auxiliaries via direct C-H heteroarylation based on arenes and heteroaromatic boronates has been disclosed. This protocol could tolerate various pyridine, pyrimidine, pyrazole, thiophene, and furan heteroaromatic boronates well, providing the desired products with high reactivities and excellent regioselectivity. The easy synthetic accessibility may offer potential for application in the synthesis of heterocyclic drug molecules containing aryl-heteroaryl motifs.

CuI-Catalyzed Decarboxylative Thiolation of Propargylic Cyclic Carbonates/Carbamates to Access Allenyl Thioethers

The first CuI-catalyzed decarboxylative thiolation of terminal alkyne-substituted cyclic carbonates/carbamates to access allenes has been developed. A wide range of hydroxymethyl- and aminomethyl-containing allenyl thioethers were smoothly obtained in good to excellent yields under mild conditions. The copper-allenylidene intermediate among the process is crucial to the decarboxylative thiolation reaction. This method opens up a new channel to access allenyl thioether compounds.

A 1,4‐Palladium Migration/Heck Sequence with Unactivated Alkenes: Stereoselective Synthesis of Trisubstituted 1,3‐Dienes

The palladium‐catalyzed cross‐coupling of ortho‐vinyl aromatic bromides and olefins was achieved through a controllable 1,4‐palladium migration/Heck cascade protocol. The reaction represents a mild, efficient and highly stereoselective method for the synthesis of trisubstituted 1,3‐dienes, especially for triaryl‐substituted ones.

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Ruthenium-catalysed oxidative coupling of vinyl derivatives and application in tandem hydrogenation

The first ruthenium-catalyzed oxidative homo- and cross-coupling of exclusive vinyl derivatives giving highly valued 1,3-diene building blocks is reported. In situ ruthenium-catalyzed hydrogenation afforded relevant adipic acid ester derivatives.