Copper‐Catalyzed Synthesis of Alkynyl Hydrazones from Alkynes and Hydrazonyl Chlorides

A novel ligand‐free synthesis of alkynyl hydrazones via coupling reaction of hydrazonyl chlorides and terminal alkynes, catalyzed by CuI led to excellent yields.     

Copper‐Catalyzed Synthesis of Pentasubstituted Pyridines from N‐Sulfonyl Ketenimines, 1,1,3,3‐Tetramethylguanidine,and Acetylene Dicarboxylates

Regioselective synthesis of pentasubstituted pyridines has been developed in moderate‐to‐good yields by the reaction of sulfonyl azides, alkynes, and a dialkyl acetylenedicarboxylate? tetramethylguanidine adduct catalyzed by CuI in MeCN at room temperature.     

Copper‐Catalyzed One‐Pot Synthesis of Functionalized Pyrroles from Sulfonyl Azides,Alkynes, and (p‐Toluenesulfonyl)methyl Isocyanide

Ketenimine intermediates generated by the addition of copper acetylides to sulfonyl azides are trapped by (p‐toluenesulfonyl)methyl isocyanide (TsCH₂NC), in the presence of Et₃N, to afford functionalized pyrroles in moderate‐to‐good yields.     

Copper‐Catalyzed One‐Pot Synthesis of N‐Sulfonylalkanimidoyl Thiocyanates from Sulfonyl Azides,Alkynes, and KSCN

Ketenimine intermediates generated by the addition of copper acetylides to sulfonyl azides are trapped by KSCN to afford N‐sulfonylalkanimidoyl thiocyanates in moderate‐to‐good yields.     

Copper‐Catalyzed Synthesis of 2H‐Thiopyran Derivatives from Alkynes,Sulfonyl Azides,Carbon Disulfide,and Malononitrile

A one‐pot synthesis of functionalized thiopyran derivatives via a Cu‐catalyzed multicomponent reaction of sulfonyl azides, arylacetylenes and dipotassium 2,2‐dicyanoethylene‐1,1‐dithiolate, generated from malononitrile and CS₂, has been developed. When alkylacetylenes were used as the terminal alkynes, N‐(alkanethioyl)‐N‐(2,2‐dicyanoethanethioyl)methanesulfonamides were obtained in good yields.     

Sulfonyl Ketenimines as Key Intermediates in One‐Pot Synthesis of N‐Sulfonyl‐2‐alkaneimidoyl Selenocyanates

Sulfonyl‐ketenimine intermediates, generated by the addition of Cu acetylides to sulfonyl azides, are trapped by KSeCN to afford N‐sulfonyl‐2‐alkaneimidoyl selenocyanates in moderate‐to‐good yields.     

Copper‐Polymer Nanocomposite Catalyst for Synthesis of 1,4‐Diphenylbutadiyne‐1,3

A new catalyst for cross‐coupling synthesis of 1,4‐diphenylbutadiyne‐1,3 was prepared by thermolysis of copper(II) poly‐5‐vinyltetrazolate. It presents heterogeneous catalyst, in which copper nanoparticles are supported on polymeric matrix surface. The catalyst is recovered, recycled, and shows high catalytic activity in cross‐coupling synthesis of 1,4‐diphenylbutadiyne‐1,3. The reaction proceeds in aerobic conditions at room temperature in the presence of pyridine.     

Reusable and Efficient Cul/TBAB‐Catalyzed Iodination of Terminal Alkynes in Water under Air

An environmentally‐friendly and operationally‐simple process for the synthesis of 1‐iodoalk‐1‐ynes under mild conditions catalyzed by CuI/TBAB in water under air was developed in this study. Catalyst loadings of CuI as low as 1–2 mol% gave 1‐iodoalk‐1‐ynes in good to high yields, and the residual aqueous solution after extraction with hexane could be reused for the next reaction without any treatment.     

Synthesis of Triborylalkenes from Terminal Alkynes by Iridium‐Catalyzed Tandem CH Borylation and Diboration

A two‐step reaction to convert terminal alkynes into triborylalkenes is reported. In the first step, the terminal alkyne and pinacolborane (HBpin) are converted into an alkynylboronate, which is catalyzed by an iridium complex supported by a SiNN pincer ligand. In the second step, treatment of the reaction mixture with CO generates a new catalyst which mediates dehydrogenative diboration of alkynylboronate with pinacolborane. The mechanism of the diboration remains unclear but it does not proceed via intermediacy of hydroboration products or via B₂pin₂.     

Palladium‐ and Solvent‐Free Synthesis of Ynones by Copper(I)‐Catalyzed Acylation of Terminal Alkynes with Acyl Chlorides under Aerobic Conditions

Air‐stable Cu^I/cryptand‐22 complex was found to be a highly active catalyst for the solvent‐free cross‐coupling reaction of terminal alkynes with different acyl chlorides in the presence of Et₃N as base to give the corresponding ynones in quantitative yields.     

A Novel and Regiospecific Synthesis of 1‐Aryl‐1H‐benzotriazoles via Copper(I)‐Catalyzed Intramolecular Cyclization Reaction

1‐Aryl‐1H‐benzotriazole derivatives were synthesized via intramolecular cyclization of easily obtained triazenes, using CuI as the catalyst, DMSO as the solvent, t‐BuONa as the base, and 1,10‐phenanthroline as the ligand, in up to 97% yield. The synthesis is regiospecific and functional group‐tolerant.     

Synthesis of Unsymmetrical 1,3‐Diynes via Pd/Cu‐Catalyzed Cross‐Coupling of Terminal Alkynes at Room Temperature

A facile and practical synthetic route of unsymmetrical 1,3‐diynes via the PdCl/CuI catalyzed oxidative coupling of two different terminal alkynes has been developed by using 3‐(diphenylphosphino)propanoic acid as a ligand in the presence of oxygen. This system is suitable for not only aromatic alkynes but also heteroaromatic and aliphatic alkynes which were transformed into the corresponding unsymmetrical 1,3‐diynes in moderate to good yields at room temperature. Moreover, the unsymmetrical 1,3‐diynes were also obtained on a multi‐gram scale. Mechanistic studies suggest that oxygen plays a key role in the catalytic cycles.     

Copper‐Catalyzed Triboration: Straightforward,Atom‐Economical Synthesis of 1,1,1‐Triborylalkanes from Terminal Alkynes and HBpin

A convenient and efficient one‐step synthesis of 1,1,1‐triborylalkanes was achieved via sequential dehydrogenative borylation and double hydroborations of terminal alkynes with HBpin (HBpin=pinacolborane) catalyzed by inexpensive and readily available Cu(OAc)₂. This process proceeds under mild conditions, furnishing 1,1,1‐tris(boronates) with wide substrate scope, excellent selectivity, and good functional‐group tolerance, and is applicable to gram‐scale synthesis without loss of yield. The 1,1,1‐triborylalkanes can be used in the preparation of α‐vinylboronates and borylated cyclic compounds, which are valuable but previously rare compounds. Different alkyl groups can be introduced stepwise via base‐mediated deborylative alkylation to produce racemic tertiary alkyl boronates, which can be readily transformed into useful tertiary alcohols.     

Copper‐Catalyzed N‐Arylation of 1,1,3,3‐TetramethylguanidinePhenyl Isocyanate Adduct

The synthesis of a novel class of 3‐[bis(dimethylamino)methylidene]‐1,1‐diarylureas via a Cu‐catalyzed multicomponent reaction of phenyl isocyanate (PhNCO), 1,1,3,3‐tetramethylguanidine, and aryl halides is described.     

Copper‐Catalyzed Amidation of Aryl Iodides in the Presence of Various Chelating Ligands

N,N′‐Dibenzylethylenediamine is presented as a new, efficient, and versatile bidentate ligand suitable for the copper catalyzed formation of the C‐N bond. This bidentate ligand has been demonstrated to facilitate the copper catalyzed cross‐coupling reactions of aryl iodides with amides to afford the desired products in good to excellent yields.     

A Mild and Efficient Method for N‐Arylnucleobase Synthesis via the Cross‐Coupling Reactions of Nucleobases with Arylboronic Acids Catalyzed by Simple Copper Salts

A simple and efficient copper‐salt catalyzed N‐arylation of nucleobases is reported. In a mixed solvent of MeOH and H₂O, the coupling products were obtained in moderate to excellent yields at room temperature within a short time. A variety of substituted N‐aryl nucleobases can be prepared through this procedure.