DMF-Promoted Redox-Neutral Ni-Catalyzed Intramolecular Hydroarylation of Alkene with Simple Arene

Catalytic Regio- and Enantioselective Remote Hydrocarboxylation of Unactivated Alkenes with CO2

The catalytic regio- and enantioselective hydrocarboxylation of alkenes with carbon dioxide is a straightforward strategy to construct enantioenriched α-chiral carboxylic acids but remains a big challenge. Herein we report the first example of catalytic highly enantio- and site-selective remote hydrocarboxylation of a wide range of readily available unactivated alkenes with abundant and renewable CO2 under mild conditions enabled by the SaBOX/Ni catalyst. The key to this success is utilizing the chiral SaBOX ligand, which combines with nickel to simultaneously control both chain-walking and the enantioselectivity of carboxylation. This process directly furnishes a range of different alkyl-chain-substituted or benzo-fused α-chiral carboxylic acids bearing various functional groups in high yields and regio- and enantioselectivities. Furthermore, the synthetic utility of this methodology was demonstrated by the concise synthesis of the antiplatelet aggregation drug (R)-indobufen from commercial starting materials.

Metal-Catalyst-Free One-Pot Aqueous Synthesis of trans-1,2-Diols from Electron-Deficient α,β-Unsaturated Amides via Epoxidation Using Oxone as a Dual Role Reagent

In organic synthesis, incorporating two functional groups into the carbon-carbon double bond of α,β-unsaturated amides is challenging due to the electron-deficient nature of the olefin moiety. Although a few examples of dihydroxylation of α,β-unsaturated amides have been demonstrated, producing cis-1,2-diols using either highly toxic OsO4 or other specialized metal reagents in organic solvents, they are limited to several specific amides. We describe herein a general and one-pot direct synthesis of trans-1,2-diols from electron-deficient α,β-unsaturated amides through dihydroxylation using oxone as a dual-role reagent in water. This reaction does not require any metal catalyst and produces non-hazardous and nontoxic K2 SO4 as the sole byproduct. Moreover, epoxidation products could also be selectively formed by adjusting the reaction conditions. By the strategy, the intermediates of Mcl-1 inhibitor and antiallergic bioactive molecule can be synthesized in one pot. The gram-scale synthesis of trans-1,2-diol which is isolated and purified by recrystallization further shows the potential applications of this new reaction in organic synthesis.

Palladium/Lewis Acid Co-catalyzed Cyclocarbonylation of (2-Aminoaryl)(aryl)methanols: An Access to 3-Aryl-indolin-2-ones

A benign approach to valuable 3-aryl-indolin-2-ones was developed based on palladium(II)/Lewis acid-cocatalyzed cyclocarbonylation of readily available (2-aminoaryl)(aryl)methanols. The protocol features producing water as the only byproduct, mild reaction conditions, and good efficiency, constituting an array of 3-arylindolin-2-ones in yields of 35 to 90%. The reaction can be easily scaled up to the gram scale in good yields.

Photocatalytic Charge-Transfer Complex Enables Hydroarylation of Alkenes for Heterocycle Synthesis

Here, we report a photocatalytic charge-transfer complex (CTC) strategy for one electron reduction of alkenes using thiolate as a catalytic electron donor. This catalytic CTC system could engage hydroarylation of both activated and unactivated alkenes for the synthesis of various heterocycles. The reactions do not require any photocatalysts or acids and are easy to perform. Mechanistic studies revealed the formation of a CTC between catalytic thiolate and alkene.

Single-carbon atom transfer to α,β-unsaturated amides from N-heterocyclic carbenes

Single-carbon atom transfer reactions are lacking in organic synthesis, partly because of the absence of atomic carbon sources under standard solution-phase conditions. We report here that N-heterocyclic carbenes can serve as atomic carbon donors through the loss of a 1,2-diimine moiety. This strategy is applicable to single-carbon atom transfer to α,β-unsaturated amides, which can be converted into homologated γ-lactams through the formation of four single bonds to one carbon center in one operation.

Transition-metal-catalyzed C-H bond alkylation using olefins: recent advances and mechanistic aspects

Transition metal catalysis has contributed immensely to C-C bond formation reactions over the last few decades, and alkylation is no exception. The superiority of such methodologies over traditional alkylation is evident from minimal reaction steps, shorter reaction times, and atom economy while also allowing control over regio- and stereo-selectivity. In particular, hydrocarbonation of alkenes has grabbed increased attention due its fundamental ability to effectively and selectively synthesise a wide range of industrially and pharmaceutically relevant moieties. This review attempts to provide a scientific viewpoint and a systematic analysis of the recent developments in transition-metal-catalyzed alkylation of various C-H bonds using simple and activated olefins. The key features and mechanistic studies involved in these transformations are described briefly.

Nickel-Catalyzed Hydroarylation Reaction: A Useful Tool in Organic Synthesis

This article describes the recent advances in the field of nickel-catalyzed hydroarylation reaction of alkenes, alkynes, and arenes. All reactions proceeded either through internal hydride transfer or in presence of...

Theoretical Insight into Ni(0)-Catalyzed Hydroarylation of Alkenes and Arylboronic Acids

The density functional theory (ωB97XD functional) is employed to clarify nickel(0)/P^tBu₃-catalyzed hydroarylation of alkenes and arylboronic acids with methanol. The computational results reveal that this reaction goes primarily through the ligand-to-ligand H transfer from the O-H bond to the alkene coordinated with nickel, complexation of arylboronic acid to the nickel-alkyl-methoxyl intermediate, attack of methoxyl on boron, transmetalation, and reductive elimination. The formation of the branched 1,1-diarylalkane, linear 1,1-diarylalkane, and alkene-dimer is also discussed in this work.

Syntheses of 3,3-Disubstituted Dihydrobenzofurans, Indolines, Indolinones and Isochromanes by Palladium-Catalyzed Tandem Reaction Using Pd(PPh3)2Cl2/(±)-BINAP as a Catalytic System

A general procedure for the tandem arylation reaction of arylbromide with heteroaryl compounds was developed by using Pd(PPh3)2Cl2/(±)-BINAP (1,1′-Binaphthalene-2,2′-diylbis (diphenylphosphane)) as catalytic system. Both sulphur- and oxygen-containing heterocycles were also employed as an efficient reagent for arylation, which gave moderate to excellent yields with moderate to good regioselectivities (5:1 to > 20:1 ir (isomer ratio)). Except for dihydrobenzofurans, indolines and indolinones, this type of tandem reaction was also expanded to synthesize isochromanes. The synthesized new compounds were well characterized through different spectroscopic techniques, such as 1H and 13C NMR (nuclear magnetic resonance), and mass spectral analysis.

Copper-catalyzed C–H [3 + 2] annulation of N-substituted anilines with α-carbonyl alkyl bromides via C(sp3)–Br/C(sp2)–H functionalization

A copper-catalyzed C–H [3 + 2] annulation of N-substituted anilines with α-carbonyl alkyl bromides for the synthesis of 3,3′-disubstituted oxindoles is developed.

Nickel-Catalyzed Regioselective Hydroalkylation and Hydroarylation of Alkenyl Boronic Esters

Metal hydride catalyzed hydrocarbonation reactions of alkenes are an efficient approach to construct new carbon-carbon bonds from readily available alkenes. However, the regioselectivity of hydrocarbonation remains challenging to be controlled. In nickel hydride (NiH) catalyzed hydrocarbonation, linear selectivity is most often obtained because of the relative stability of the linear Ni-alkyl intermediate over its branched counterpart. Herein, we show that the boronic pinacol ester (Bpin) group directs a Ni-catalyzed hydrocarbonation to occur at its adjacent carbon center, resulting in formal branch selectivity. Both alkyl and aryl halides can be used as electrophiles in this hydrocarbonation, providing access to a wide range of secondary alkyl Bpin derivatives, which are valuable building blocks in synthetic chemistry. The utility of the method is demonstrated by the late-stage functionalization of natural products and drug molecules, the synthesis of an anticancer agent, and iterative syntheses.

Direct Csp3-H methylenation of 2-arylacetamides using DMF/Me2NH-BH3 as the methylene source

A direct Csp3-H methylenation of 2-arylacetamides using DMF/Me2NH-BH3 as the methylene source was developed. The formyl group of DMF delivered the carbon and one hydrogen atoms, and the Me2NH-BH3 donated the remaining one hydrogen atom. This protocol offers a new alternative to make useful 2-arylacrylamides from simple starting materials.

Carboiodination Catalyzed by Nickel

A novel nickel-catalyzed cycloisomerization reaction forming a new carbon-carbon bond while preserving the carbon-halogen bond has been developed. A cheap and readily available Ni-catalyst is employed to generate nitrogen containing heterocycles in good to excellent yields and the procedure is readily scalable. The more readily available aryl bromides were also cyclized with the addition of potassium iodide to generate the respective alkyl iodides. A rare dual ligand system employing a bisphosphine and bisphosphine monoxide was used to achieve enantioenriched products.

Recent Uses of N,N-Dimethylformamide and N,N-Dimethylacetamide as Reagents

N,N-Dimethylformamide and N,N-dimethylacetamide are multipurpose reagents which deliver their own H, C, N and O atoms for the synthesis of a variety of compounds under a number of different experimental conditions. The review mainly highlights the corresponding literature published over the last years.