Cobalt-Catalyzed Vinylation of Aromatic Halides Using β-Halostyrene: Experimental and DFT Studies

Recent advances in iron-catalysed coupling reactions for the construction of the C(sp2)-C(sp2) bond

The advancement of transition-metal-catalyzed coupling reactions has been demonstrated as a highly effective strategy for the formation of carbon-carbon bonds, which serve as the fundamental basis for organic synthetic chemistry. Given that iron represents one of the most economical and ecologically sustainable metallic elements available, the exploration and enhancement of iron-catalysed coupling reactions have garnered increasing interest within the scientific community. In recent years, numerous iron-catalysed reactions have been reported, showcasing their efficacy in establishing C-C bonds. In this minireview, we present a systematic analysis of C(sp²)-C(sp²) bond formation via iron-catalysed coupling reactions as documented in the extant literature.

Stereospecific Iron-Catalyzed Carbon (sp2)-Carbon (sp2) Cross-Coupling of Aryllithium with Vinyl Halides

We present herein an efficient synthetic protocol involving iron-catalyzed cross-coupling of organolithium compounds with vinyl halides as key coupling partners. More than 30 examples were obtained with moderate to good yields and high stereoselectivities. The practicality of this method is evidenced by a gram-scale synthesis. In addition, a preliminary mechanistic investigation was also performed.

Cobalt-Catalyzed 1,4-Aryl Migration/Desulfonylation Cascade: Synthesis of α-Aryl Amides

A cobalt-catalyzed 1,4-aryl migration/disulfonylation cascade applied to α-bromo N-sulfonyl amides was developed. The reaction was highly chemoselective, allowing the preparation of α-aryl amides possessing a variety of functional groups. The method was used as the key step to synthesize an alkaloid, (±)-deoxyeseroline. Mechanistic investigations suggest a radical process.

Cobalt-catalyzed carboxylation of aryl and vinyl chlorides with CO2

The transition-metal-catalyzed carboxylation of aryl and vinyl chlorides with CO2 is rarely studied, and has been achieved only with a Ni catalyst or combination of palladium and photoredox. In this work, the cobalt-catalyzed carboxylation of aryl and vinyl chlorides and bromides with CO2 has been developed. These transformations proceed under mild conditions and exhibit a broad substrate scope, affording the corresponding carboxylic acids in good to high yields.

Reductive Cross-Coupling of Vinyl Electrophiles

The synthesis of alkenes (olefins) is a central subject in the synthetic community. The transition-metal-catalyzed reductive cross-coupling of vinyl electrophiles has emerged as a promising tool to produce alkenes with improved flexibility, structural complexity, and functionality tolerance. In this review, we summarized the progress in this field with respect to cross-electrophile couplings and reductive Heck reactions using vinyl electrophiles.

1 Introduction

2 Cross-Electrophile Coupling of Vinyl Electrophiles

3 Reductive Heck Reaction of Vinyl Electrophiles

4 Summary and Outlook

From 4-nitrotoluene and 4,4′-dinitrobibenzyl to E-4,4′-dinitrostilbene: an electrochemical approach

Oxidation of nitroarenes under electroreductive conditions: the electrochemical reduction of 4,4′-dinitrobibenzyl and 4-nitrotoluene leads to the dianion of E-4,4′-dinitrostilbene.

Cobalt-Catalyzed C(sp2)-C(sp3) Cross-Coupling Reactions of Diarylmanganese Reagents with Secondary Alkyl Iodides

A cobalt-catalyzed cross-coupling of diarylmanganese reagents with secondary alkyl iodides using the THF-soluble salt CoCl₂·2LiCl, which leads to the cross-coupling products in up to 92% yield, is reported. High diastereoselectivities can be reached in these cross-couplings (dr up to 99:1). Remarkably, rearrangement of secondary alkyl iodides to unbranched products was not observed in these C-C forming reactions.

Ni-catalyzed reductive coupling of α-halocarbonyl derivatives with vinyl bromides

This work describes the vinylation of α-halo carbonyl compounds with vinyl bromides under Ni-catalyzed reductive coupling conditions. While aryl-conjugated vinyl bromides entail pyridine as the sole labile ligand, the alkyl-substituted vinyl bromides require both bipyridine and pyridine as the co-ligands.

Practical Iron- and Cobalt-Catalyzed Cross-Coupling Reactions between N-Heterocyclic Halides and Aryl or Heteroaryl Magnesium Reagents

The reaction scope of iron- and cobalt-catalyzed cross-coupling reactions in the presence of isoquinoline (quinoline) in the solvent mixture tBuOMe/THF has been further investigated. Various 2-halogenated pyridine, pyrimidine, and triazine derivatives were arylated under these mild conditions in excellent yields. The presence of isoquinoline allows us to perform Fe-catalyzed cross-coupling reactions between 6-chloroquinoline and aryl magnesium reagents. Furthermore, it was found that the use of 10% N,N-dimethylquinoline-8-amine increases the yields of some Co-catalyzed cross-coupling reactions with chloropyridines bearing electron-withdrawing substituents.

Controlling olefin isomerization in the heck reaction with neopentyl phosphine ligands

The use of neopentyl phosphine ligands was examined in the coupling of aryl bromides with alkenes. Di-tert-butylneopentylphosphine (DTBNpP) was found to promote Heck couplings with aryl bromides at ambient temperature. In the Heck coupling of cyclic alkenes, the degree of alkene isomerization was found to be controlled by the choice of ligand with DTBNpP promoting isomerization to a much greater extent than trineopentylphosphine (TNpP). Under optimal conditions, DTBNpP provides high selectivity for 2-aryl-2,3-dihydrofuran in the arylation of 2,3-dihydrofuran, whereas TNpP provided high selectivity for the isomeric 2-aryl-2,5-dihydrofuran. A similar complementary product selectivity is seen in the Heck coupling of cyclopentene. Heck coupling of 2-bromophenols or 2-bromoanilides with 2,3-dihydrofurans affords 2,5-epoxybenzoxepin and 2,5-epoxybenzazepins, respectively.

Nickel-catalyzed asymmetric reductive cross-coupling between vinyl and benzyl electrophiles

A Ni-catalyzed asymmetric reductive cross-coupling between vinyl bromides and benzyl chlorides has been developed. This method provides direct access to enantioenriched products bearing aryl-substituted tertiary allylic stereogenic centers from simple, stable starting materials. A broad substrate scope is achieved under mild reaction conditions that preclude the pregeneration of organometallic reagents and the regioselectivity issues commonly associated with asymmetric allylic arylation.