Nickel-Catalyzed Molybdenum-Promoted Carbonylative Synthesis of Benzophenones

Current-Regulated Selective Nickel-Catalyzed Electroreductive Cross-Electrophile Carbonylation to β/γ-Hydroxy Ketones

The nickel catalyzed multi-component cross-electrophile carbonylation which emerges as a powerful and efficient method for constructing diverse ketones has attracted increasing attention of organic chemists. However, the selectivity of this reaction poses a significant challenge. In this work, we have developed a current-regulated selective nickel-catalyzed electroreductive cross-electrophile carbonylation, which offers a direct convergent synthesis of β/γ-hydroxy ketones, which represent pivotal structural motifs found in numerous natural products, bioactive molecules, pharmaceutical compounds, and essential building blocks. A diverse range of multi-substituted β/γ-hydroxyketones can be accessed with high chemo- and regioselectivity from epoxides, aryl iodides, and a simple CO source (ClCO2Pr). This electroreductive carbonylation strategy exhibits high functional group tolerance and can be applied in late-stage derivatization of drugs and natural products. Notably, chiral epoxides can be employed as reactants with chirality retention, enabling the synthesis of asymmetric β-hydroxy ketones. Our approach demonstrates a novel electrochemical selectivity-controlled strategy in multi-component cross-electrophile coupling.

Dithiocarbamate as a Carbonyl Alternative in Pd-Catalyzed Carbonylative Homocoupling of Organoboronic Acids

We have developed a novel protocol for carbonylative homocoupling of arylboronic acids using dithiocarbamate esters as the carbonyl alternative. A series of arylboronic acids underwent smooth reaction with dithiocarbamate ester (Me2NCS2Me) in the presence of Pd(PPh3)2Cl2 catalyst, Cu(OAc)2·H2O additive, and Na2CO3 in DCE solvent, producing the biaryl ketones efficiently. The mechanism has been studied with the help of several control experiments that reveal the probability of thioamide intermediacy. Chemoselective homocoupling allows the postsynthetic modification of the product.

Carbonylative Self-Coupling of Aryl Boronic Acids Using a Confined Pd Catalyst within Melamine Dendron and Fibrous Nano-Silica: A CO Surrogate Approach

Development of heterogeneous catalysts with tunable activity and selectivity has posed a persistent challenge. This study addresses this challenge by fabricating a hybrid environment through the combination of mesoporous silica and N-rich melamine dendron via covalent grafting, allowing for controllable growth and encapsulation of Pd NPs. This catalyst presented an excellent catalytic activity for the oxidative carbonylative self-coupling of aryl boronic acids to afford symmetric biaryl ketones using N-formyl saccharin as a sustainable solid CO source and Cu as a co-catalyst.

Oxidative C-H/N-H Carbonylation of Benzamide by Nickel Catalysis with CO as the Carbonyl Source

An efficient and direct carbonylation of aminoquinoline benzamides has been developed using abundant and inexpensive Ni(OAc)₂·4H₂O as the catalyst and carbon monoxide as a cost-efficient C1 building block. This process features good functional-group tolerance and can be conducted on gram scale. The directing group can be easily removed under mild conditions.

Nickel-Catalyzed Carbonylative Synthesis of α,β-Unsaturated Thioesters from Vinyl Triflates and Arylsulfonyl Chlorides

A straightforward and efficient synthesis of α,β-unsaturated thioesters has been developed via a nickel-catalyzed thiocarbonylation reaction of vinyl triflates with arylsulfonyl chlorides. With Mo(CO)₆ as both CO source and reductant, a variety of α,β-unsaturated thioesters were obtained in moderate to good yields with very good functional group compatibility. It is noteworthy that the present method is the first example on nickel-catalyzed carbonylative synthesis of α,β-unsaturated thioesters by using arylsulfonyl chlorides as the coupling partner.

Nickel-Catalyzed One-Pot Carbonylative Synthesis of 2-Mono- and 2,3-Disubstituted Thiochromenones from 2-Bromobenzenesulfonyl Chlorides and Alkynes

A nickel-catalyzed one-pot carbonylation reaction of 2-bromobenzenesulfonyl chlorides with alkynes for the synthesis of thiochromenones has been established. Both terminal and internal alkynes were suitable substrates in this carbonylative transformation, and a broad range of 2-mono- and 2,3-disubstituted thiochromenone products were obtained in moderate to good yields with quite high functional group compatibility. Notably, this procedure presents the first example of nickel-catalyzed carbonylative synthesis of thiochromenones with 2-bromobenzenesulfonyl chlorides as a promising sulfur precursor.

Nickel-catalyzed cascade carbonylative synthesis of N-benzoyl indoles from 2-nitroalkynes and aryl iodides

A nickel-catalyzed carbonylative cyclization of 2-nitroalkynes and aryl iodides has been developed for the expedite construction of N-benzoyl indole scaffolds.

Tandem Synthesis of 2-Carboxybenzofurans via Sequential Cu-Catalyzed C-O Coupling and Mo(CO)6-Mediated Carbonylation Reactions

A modular tandem synthesis of 2-carboxybenzofurans from 2-gem-dibromovinylphenols has been established based on a sequence of Cu-catalyzed intramolecular C-O coupling and Mo(CO)₆-mediated intermolecular carbonylation reactions. This protocol allowed one-step access to a broad variety of functionalized benzofuran-2-carboxylic acids, esters, and amides in good to excellent yields under Pd- and CO gas-free conditions.

Nickel-catalyzed allylic carbonylative coupling of alkyl zinc reagents with tert-butyl isocyanide

Transition metal-catalyzed carbonylation with carbon nucleophiles is one of the most prominent methods to construct ketones, which are highly versatile motifs prevalent in a variety of organic compounds. In comparison to the well-established palladium catalytic system, the nickel-catalyzed carbonylative coupling is much underdeveloped due to the strong binding affinity of CO to nickel. By leveraging easily accessible tert-butyl isocyanide as the CO surrogate, we present a nickel-catalyzed allylic carbonylative coupling with alkyl zinc reagent, allowing for the practical and straightforward preparation of synthetically important β,γ-unsaturated ketones in a linear-selective fashion with excellent trans-selectivity under mild conditions. Moreover, the undesired polycarbonylation process which is often encountered in palladium chemistry could be completely suppressed. This nickel-based method features excellent functional group tolerance, even including the active aryl iodide functionality to allow the orthogonal derivatization of β,γ-unsaturated ketones. Preliminary mechanistic studies suggest that the reaction proceeds via a π-allylnickel intermediate.

In contrast to the well-established palladium-catalyzed version, the nickel-catalyzed carbonylative coupling is underdeveloped. Here the authors report a nickel-catalyzed allylic carbonylative coupling with alkyl zinc reagents, allowing for preparation of β,γ-unsaturated ketones in a linear-selective fashion.

Synthesis of α,β-alkynyl ketones via the nickel catalysed carbonylative Sonogashira reaction using oxalic acid as a sustainable C1 source

An efficient and economic nickel-dppb catalyzed, carbonylative Sonogashira cross-coupling reaction was demonstrated to provide rapid access to various α,β-alkynyl ketones from aryl iodides and terminal alkynes using oxalic acid as the ex situ C1 source in a double vial (DV) system. Notably, the role of the ligand in combination with the Ni catalyst for the selective formation of carbonylative Sonogashira products was investigated and supported with control experiments. Yet, no reports are available for carbonylative Sonogashira coupling by using a CO-surrogate under Ni-catalyzed conditions. In this process, for the first time, oxalic acid is used as an ex situ solid, bench stable, easy to handle and efficient CO surrogate in a DV-system for the carbonylative Sonogashira coupling reaction with vast substrate scope.