Photoredox-catalyzed carbonylative acylation of styrenes with Hantzsch esters.

Ketones exist widely in naturally occurring products and are indispensable building blocks in organic synthesis. Carbonylation represents one of the most straightforward methods for ketone preparation and has become an attractive field in modern organic chemistry as well. Among the strategies, photocatalytic carbonylation is also worthy of further exploration. Herein, we developed a three-component carbonylation that provides a new method for the synthesis of ketones from Hantzsch esters, CO and styrenes. The reaction was performed under a blue light environment and yields a series of ketones with moderate to good yields.

Iron-Catalyzed Aminoalkylative Carbonylative Cyclization of Alkenes toward α-Tetralones.

Carbonylative multifunctionalization of alkenes is an efficient approach to introduce multiple functional groups into one molecule from easily available materials. Herein, we developed an iron-catalyzed radical relay carbonylative cyclization of alkenes with acetamides. Various α-tetralones can be constructed in moderate yields from readily available substrates with an earth-abundant iron salt as the catalyst.

Cobalt-catalyzed aminoalkylative carbonylation of alkenes toward direct synthesis of γ-amino acid derivatives and peptides.

γ-Amino acids and peptides analogues are common constituents of building blocks for numerous biologically active molecules, pharmaceuticals, and natural products. In particular, γ-amino acids are providing with better metabolic stability than α-amino acids. Herein we report a multicomponent carbonylation technology that combines readily available amides, alkenes, and the feedstock gas carbon monoxide to build architecturally complex and functionally diverse γ-amino acid derivatives in a single step by the implementation of radical relay catalysis. This transformation can also be used as a late-stage functionalization strategy to deliver complex, advanced γ-amino acid products for pharmaceutical and other areas.

Cobalt-Catalyzed Carbonylative Synthesis of 4-Oxobutanoates from Formamide and Ethylene.

The direct concurrent installation of amide and ester groups across olefin motifs represents a powerful and promising functionalization tool in organic chemistry. Herein, a ligand-free cobalt-catalyzed four-component radical relay carbonylative difunctionalization of ethylene for the synthesis of 4-oxobutanoates has been developed. Valuable C4 building blocks were produced in a highly atom-economical fashion.

Site-selective carbonylation of arenes via C(sp2)-H thianthrenation: direct access to 1,2-diarylethanones.

Herein, a new reaction for the site-selective carbonylation of arenes via C(sp2)-H thianthrenation under mild conditions has been developed. With low loadings of palladium catalysts, various desired 1,2-diarylethanones are produced in good yields. This strategy also enables the late-stage modification of complex molecules, which was previously challenging with similar carbonylative Negishi-type reactions.

Copper-Catalyzed Direct Carbonylation of Carbenes toward the Synthesis of Propanedioic Acid Derivatives.

Carbenes are highly active reaction intermediates, which can be used as reaction precursors to modify organisms, drugs, and material molecules. In this work, we realized a new cheap metal-catalyzed carbonylation of carbene to give propanedioic acid derivatives. With copper salt as the catalyst, synthetically important malonates and related compounds were produced in good yields under mild reaction conditions.

Non-Noble Metal-Catalyzed Carbonylative Multi-Component Reactions.

Carbonylative multi-component reactions (CMCR), having four or more kinds of starting materials, provide an efficient strategy for the preparation of polyfunctional carbonylated compounds. Diverse CMCR utilizing non-noble transition-metal catalysts have been developed. This review summarized and discussed the recent advances in non-noble metal-catalyzed carbonylative multi-component reactions.

Nickel-Catalyzed Four-Component Carbonylation of Ethers and Olefins: Direct Access to γ-Oxy Esters and Amides.

Multi-component carbonylation of olefins, a reaction that installs both a carbon-carbon(heteroatom) bond and a carbonyl group across the double bond, is an attractive strategy for alkene functionalization. Herein, we developed a novel nickel-catalyzed four-component carbonylation of olefins with ethers under low CO gas pressure. Using alcohols and amines as the reaction partner, diverse γ-oxy-substituted esters and amides were produced in good yields with excellent functional group tolerance. Notably, Naftidrofuryl, a medicine for the treatment of cerebrovascular disease (CVD), can be synthesized by this process straightforwardly.

Palladium-Catalyzed Desulfonative Carbonylation of Thiosulfonates: Elimination of SO2 and Insertion of CO.

A palladium-catalyzed desulfonative carbonylation of thiosulfonates has been explored. Without any additive, a series of S-aryl/alkyl benzenesulfonothioates were successfully transformed to thioesters in moderate to excellent yields by SO2 extrusion and CO insertion under the pressure of 1 bar of CO. The solvent dimethylacetamide (DMAc) facilitated this desulfonative carbonylation due to its high absorbing ability of SO2.

Controllable access to trifluoromethyl-containing indoles and indolines: palladium-catalyzed regioselective functionalization of unactivated alkenes with trifluoroacetimidoyl chlorides.

The synthesis of diverse products from the same starting materials is always attractive in organic chemistry. Here, a palladium-catalyzed substrate-controlled regioselective functionalization of unactivated alkenes with trifluoroacetimidoyl chlorides has been developed, which provides a direct but controllable access to a variety of structurally diverse trifluoromethyl-containing indoles and indolines. In more detail, with respect to γ,δ-alkenes, 1,1-geminal difunctionalization of unactivated alkenes with trifluoroacetimidoyl chloride enables the [4 + 1] annulation to produce indoles; as for ß,γ-alkenes, a [3 + 2] heteroannulation with the hydrolysis product of trifluoroacetimidoyl chloride through 1,2-vicinal difunctionalization of alkenes occurs to deliver indoline products. The structure of alkene substrates differentiates the regioselectivity of the reaction.

Cobalt-Catalyzed Direct Aminocarbonylation of Ethers: Efficient Access to α-Amide Substituted Ether Derivatives.

Ethers are of central importance in the fields of biomass, energy, and organic chemistry. Herein, a novel cobalt-catalyzed carbonylative coupling of ethers with amines to construct α-carbonylated ethers has been achieved. Remarkably, Alfuzosin, a medicine for treatment of benign prostatic hyperplasia (BPH), can be synthesized by this process straightforwardly. Notably, this protocol presents the first example on the direct carbonylative reaction of ethers.

Palladium-Catalyzed Direct Dicarbonylation of Amines with Ethylene to Imides.

The selective and effective conversion of low-cost and simple bulk chemicals into high value-added products through catalytic strategy has a wide range of practical significance. Here, a palladium-catalyzed method for the direct and efficient dicarbonylation of amines with basic industrial feedstock ethylene to imide has been developed. Moderate to excellent yields of the desired imides can be produced from readily available amines in a straightforward manner.

The cascade coupling/iodoaminocyclization reaction of trifluoroacetimidoyl chlorides and allylamines: metal-free access to 2-trifluoromethyl-imidazolines.

A metal-free cascade coupling/iodoaminocyclization reaction for the rapid assembly of 2-trifluoromethyl-imidazolines has been disclosed. The transformation applies readily accessible trifluoroacetimidoyl chlorides, allylamines and N-iodosuccinimides as the starting substrates, achieving an efficient and straightforward pathway to construct diverse imidazoline derivatives. Excellent efficiency of the reaction is observed (higher than 90% isolated yield for half of the examples), and the obtained imidazoline products bearing a pendent iodomethyl group could be easily transformed into other synthetically valuable compounds.

FeCl3-Mediated Synthesis of 2-(Trifluoromethyl)quinazolin-4(3H)-ones from Isatins and Trifluoroacetimidoyl Chlorides.

An FeCl3-mediated cascade coupling/decarbonylative annulation reaction for the efficient construction of 2-(trifluoromethyl)quinazolin-4(3H)-ones has been developed. This transformation employs readily available isatins and trifluoroacetimidoyl chlorides as the starting materials, providing a facile and practical route to diverse biologically relevant quinazolin-4(3H)-one derivatives. A plausible reaction pathway has been proposed based on the mechanistic observations.

Carbonylative synthesis of heterocycles involving diverse CO surrogates.

Recent advances in the carbonylative synthesis of heterocycles by using diverse CO surrogates as sources of CO are summarized and discussed. The merger of carbonylative transformations involving CO surrogates with heterocyclic compound syntheses provides a powerful and promising tool for the construction of a series of carbonyl-containing heterocyclic compounds. In contrast to toxic and flammable gaseous carbon monoxide, most of the CO surrogates are readily available, bench-stable, harmless and easy to handle. This feature article will mainly focus on heterocycle syntheses involving CO surrogates, including formic acid, formates, molybdenum hexacarbonyl, etc.

Palladium-Catalyzed Carbonylative Synthesis of α-Branched Enones from Aryl Iodides and Arylallenes.

In this communication, an interesting carbonylation protocol for the preparation of α-branched enones has been established. Starting from readily available aryl iodides and allenes, with formic acid as the CO source and reductant, moderate to good yields of the desired enones were isolated. Although it is a carbonylation methodology, the use of a CO source can avoid the manipulation of CO gas directly. Notably, this procedure also presents the first example on carbonylative synthesis of α-branched enones.