Isocyanide-Induced Activation of Copper Sulfate: Direct Access to Functionalized Heteroarene Sulfonic Esters

A novel and direct approach to alkyl/aryl heteroarene sulfonic esters using copper sulfate as the environmentally benign inorganic sulfonation reagent was first realized with the aid of isocyanide. A variety of heterocycles reacted to afford the corresponding sulfonic esters through C-H functionalization. In this transformation, the otherwise inert copper sulfate was unusually activated by an isocyanide and employed as the source of the sulfonic substituents in an unprecedented fashion. The findings suggest that an appropriate activator may liberate the chemical activities of some relatively inert inorganic salts for organic synthesis.

Use of unprotected amino acids in metal-free tandem radical cyclization reactions: divergent synthesis of 6-alkyl/acyl phenanthridines

We demonstrated a metal-free protocol for the construction of C–C bonds utilizing unprotected amino acids as radical sources.

Ag(i)/persulfate-catalyzed decarboxylative coupling of α-oxocarboxylates with organotrifluoroborates in water under room temperature

The decarboxylative coupling of α-oxocarboxylates and organotrifluoroborates was carried out smoothly in water under room temperature. This novel and simple method is efficient, using AgNO₃/K₂S₂O₈ catalytic system to generate diarylketone products.

Free-radical initiated cascade methylation or trideuteromethylation of isocyanides with dimethyl sulfoxides

The methylation or trideuteromethylation reaction of isocyanides with dimethyl sulfoxides in a radical way is developed, which offers a low-cost, easy-operation cascade methylation strategy for the synthesis of phenanthridines or isoquinolines.

A one-pot synthesis of [1,2,3]triazolo[1,5-a]quinoxalines from 1-azido-2-isocyanoarenes with high bond-forming efficiency

An efficient approach to prepare 1,2,3-triazolo[1,5-a]quinoxaline scaffolds, starting from 1-azido-2-isocyanoarenes and terminal acetylenes or substituted acetaldehydes, has been developed.

Metal-catalyzed C–H functionalization involving isocyanides

This review demonstrates the metal-catalyzed incorporation of isocyanides into C–H functionalization to establish complicated reactions utilizing synergistic effects.

Visible-Light-Induced Cascade Reaction of Isocyanides and N-Arylacrylamides with Diphenylphosphine Oxide via Radical C-P and C-C Bond Formation

An effective photoredox-mediated tandem phosphorylation/cyclization reaction of diphenylphosphine oxide with three types of radical acceptors leads to P(O)Ph₂-containing phenanthridines, isoquinolines, and indolin-2-ones by formation of both C-P and C-C bonds. [Ir(ppy)₂(dtbpy)]PF₆ (1 mol %) was used as the catalyst, CsF or Cs₂CO₃ as the base, and K₂S₂O₈ as the oxidant. A series of functional groups can be tolerated at room temperature. Moderate to good yields were generated.

Ag-catalyzed C-H/C-C bond functionalization

Silver, known and utilized since ancient times, is a coinage metal, which has been widely used for various organic transformations in the past few decades. Currently, the silver-catalyzed reaction is one of the frontier areas in organic chemistry, and the progress of research in this field is very rapid. Compared with other transition metals, silver has long been believed to have low catalytic efficiency, and most commonly, it is used as either a cocatalyst or a Lewis acid. Interestingly, the discovery of Ag-catalysis has been significantly improved in recent years. Especially, Ag(i) has been demonstrated as an important and versatile catalyst for a variety of organic transformations. However, so far, there has been no systematic review on Ag-catalyzed C-H/C-C bond functionalization. In this review, we will focus on the development of Ag-catalyzed C-H/C-C bond functionalization and the corresponding mechanism.

Oxidative cyclization of alkenoic acids promoted by AgOAc

Alkenoic acids derived from salicylic acid and analogues undergo an unexpected oxidative cyclization process triggered by AgOAc leading to 4H-benzo[d][1,3]dioxin-4-ones. The process is affected by the substitution on the aryl and the allyl units.

Silver-catalyzed oxidative decarboxylation of difluoroacetates: efficient access to C–CF2 bond formation

Ag(i)-catalyzed oxidative decarboxylative gem-difluoromethylenation of difluoroacetates with isonitriles has been developed for the formation of C–CF₂ bonds.

Co(acac)2/O2-catalyzed oxidative isocyanide insertion with 2-vinylanilines: efficient synthesis of 2-aminoquinolines

A series of 2-aminoquinolines were afforded by Co(acac)₂ catalyzed isocyanide insertion with 2-vinylanilines under an O₂ atmosphere.

Manganese(ii)-catalyzed modular synthesis of isoquinolines from vinyl isocyanides and hydrazines

An efficient manganese(ii)-catalyzed oxidative radical cascade reaction was developed from vinyl isocyanides and hydrazines leading to the modular synthesis of multi-substituted isoquinolines, phenanthridines and pyrrolo[1,2-a]quinoxalines.

Recent progress in imidoyl radical-involved reactions

This review discusses the recent progress in imidoyl radical-involved reactions including the synthesis of functionalized heterocycles, nitriles, imines, amines,etc.

Recent advances in catalytic decarboxylative acylation reactions via a radical process

This review highlights the recent advances in radical decarboxylative cross-coupling reactions of α-keto acids which provide powerful tools for C–C and C–X bond formations.

An isocyanide insertion approach to substituted pyrrolo[2,3-b]quinolines under metal-free and azide-free conditions

An isocyanide insertion approach to construct the pyrrolo[2,3-b]quinoline skeleton by an I₂/CHP mediated reaction of aminome-thylenecyclo-propanes (amino-MCPs) is developed.

Tandem cycloaddition–decarboxylation of α-keto acid and isocyanide under oxidant-free conditions towards monosubstituted oxazoles

An efficient method, tandem [3 + 2] cycloaddition–decarboxylation of α-keto acid and isocyanide promoted by copper salt, has been developed for constructing monosubstituted oxazole. The elegant approach ingeniously avoids consuming excess oxidants.

Palladium-catalyzed intramolecular C(sp(2))-H imidoylation for the synthesis of six-membered N-heterocycles

A new strategy for the construction of phenanthridine and isoquinoline scaffolds, starting from arenes containing a pending isocyanide moiety under palladium catalysis, has been developed. This process involves sequential intermolecular isocyanide insertion to an aryl palladium(II) intermediate and intramolecular aromatic C-H activation as key steps. Alkyl palladium(II) intermediate lacking β-hydrogen is also applicable to this reaction, generating unique bisheterocyclic scaffolds with three C-C bonds being formed consecutively.

Metal-free radical oxidative decarboxylation/cyclization of acyl peroxides and 2-isocyanobiphenyls

A radical oxidative decarboxylation/cyclization of acyl peroxides and 2-isocyanobiphenyls was achieved, leading to 6-substituted phenanthridines under metal-free and base-free conditions.

Preparation of phenanthrenes from ortho-amino-biphenyls and alkynes via base-promoted homolytic aromatic substitution

Phenanthrenes are prepared from ortho-aminobiphenyls and acetylenes via base-promoted homolytic aromatic substitution.

Light triggered addition/annulation of 2-isocyanobiphenyls toward 6-trifluoromethyl-phenanthridines under photocatalyst-free conditions

A photocatalyst-free, light promoted sequential radical addition/annulation of 2-isocyanobiphenyls to 6-trifluoromethyl phenanthridines with high efficiency is presented.

Recent advances in the synthesis of nitrogen heterocycles via radical cascade reactions using isonitriles as radical acceptors

Radical isonitrile insertion reactions are highly valuable for the construction of N-containing heterocycles such as phenanthridines, quinolines, isoquinolines, quinoxalines and indoles.

NIS/CHP-mediated reaction of isocyanides with hydrazones: access to aminopyrazoles

A NIS/CHP-mediated reaction of isocyanides with hydrazones to construct aminopyrazoles has been developed.

Synthesis of oxazoles by silver catalysed oxidative decarboxylation–cyclization of α-oxocarboxylates and isocyanides

This work developed a silver catalysed synthesis of oxazoles by the oxidative decarboxylation–cyclization of α-oxocarboxylates and isocyanides.