ZnII‐ and AuI‐Catalyzed Regioselective Hydrative Oxidations of 3‐En‐1‐ynes with Selectfluor: Realization of 1,4‐Dioxo and 1,4‐Oxohydroxy Functionalizations

Catalytic 1,4‐dioxo functionalizations of 3‐en‐1‐ynes to (Z)‐ and (E)‐2‐en‐1,4‐dicarbonyl compounds are described. This regioselective difunctionalization was achieved in one‐pot operation through initial alkyne hydration followed by in situ Selectfluor oxidation. The presence of pyridine alters the reaction chemoselectivity to give 4‐hydroxy‐2‐en‐1‐carbonyl products instead. A cooperative action of pyridine and Zn^II assists the hydrolysis of key oxonium intermediate.     

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 3‐Acyl‐4‐alkenylpyrrolidines by Platinum‐Catalyzed Hydrative Cyclization of Allenynes

A series of nitrogen‐tethered allenynes (‘5‐aza‐1,2‐dien‐7‐ynes’) 1 were transformed to the corresponding 3‐acyl‐4‐alkenylpyrrolidines 3 when treated with a catalytic amount of PtCl₂ in MeOH at 70°. Initial Pt‐promoted cyclization forms a nonclassical carbocationic intermediate. In contrast to the cycloisomerization in toluene, which produced the bicyclic cyclobutenes 2 , the intermediate is intercepted by addition of an oxygen nucleophile to achieve the formal hydrative cyclization.     

Short communication: An alternative and effective catalyst in the stereo‐specific reaction of Z‐1‐aryl‐1‐stannyl‐2‐silylethenes with allyl bromide

The Pd(dba)₂‐catalyzed reaction of Z‐1‐aryl‐1‐(tributylstannyl)‐2‐(trimethylsilyl)ethenes with allyl bromide in the presence of copper(I) iodide is reported for the first time. The reaction in the presence of 0.5 mol% Pd(dba)₂ and 8 mol% CuI in dimethylformamide takes place at room temperature to give E‐2‐aryl‐1‐(trimethylsilyl)penta‐1,4‐dienes exclusively in isolated yields of 62–99%. A putative reaction mechanism is proposed. Copyright © 2005 John Wiley & Sons, Ltd.     

CuI‐Catalyzed Multicomponent Synthesis of Aminoindolizines from Aldehydes,Amines, and Alkynes under Solvent‐Free Conditions

A direct and efficient approach to 1‐aminoindolizines through three‐component one‐pot reaction of heteroaryl aldehydes, secondary amines and terminal alkynes catalyzed by CuI under solvent‐free conditions has been developed. This methodology provides a rapid access to substituted aminoindolizines with good yields (up to 97%).     

Stereospecific synthesis of a family of novel (E)‐2‐aryl‐1‐silylalka‐1,4‐dienes or (E)‐4‐aryl‐5‐silylpenta‐1,2,4‐trienes via a cross‐coupling of (Z)‐silyl(stannyl)ethenes with allyl halides or propargyl bromide

Stereospecific synthesis of a family of novel (E)‐2‐aryl‐1‐silylalka‐1,4‐dienes or (E)‐4‐aryl‐5‐silylpenta‐1,2,4‐trienes via a cross‐coupling of (Z)‐silyl(stannyl)ethenes with allyl halides or propargyl bromide is described. In the reaction with allyl bromide, either a Pd(dba)₂? CuI combination (dba, dibenzylideneacetone) in DMF or copper(I) iodide in DMSO–THF readily catalyzes or mediates the coupling reaction of (Z)‐silyl(stannyl)ethenes at room temperature, producing novel vinylsilanes bearing an allyl group β to silicon with cis ‐disposition in good yields. Allyl chlorides as halides can be used in the CuI‐mediated reaction. CuI alone much more effectively mediates the cross‐coupling reaction with propargyl bromide in DMSO–THF at room temperature compared with a Pd(dba)₂? CuI combination catalysis in DMF, providing novel stereodefined vinylsilanes bearing an allenyl group β to silicon with cis ‐disposition in good yields. Copyright © 2008 John Wiley & Sons, Ltd.     

Efficiency enhancement of solid‐state dye sensitized solar cell by in situ deposition of CuI

Solid‐state dye‐sensitized solar cells based on nanocrystalline TiO₂ thin film with the structures TiO₂/dye/CuI/Pt and TiO₂/dye/In situ CuI/CuI/Pt were developed in order to compare the use of In situ deposited CuI (In situ CuI). Porosity of the screen‐printed nanoporous TiO₂ thin film was enhanced by the addition of polystyrene balls. Evidence of decrease in interfacial resistance was observed by electrochemical impedance measurement for the device with In situ deposited CuI as compared to that without In situ deposited CuI as hole conductor. This was attributed to good interfacial contacts and better charge transfer between CuI and dye‐sensitized TiO₂ nanoparticles, which resulted in the enhancement of power conversion efficiency from 0.058 to 1.01%. Copyright © 2008 John Wiley & Sons, Ltd.     

CuI/amino acid‐catalyzed coupling and cyclization of β‐bromo‐α,β‐unsaturated amides with terminal alkynes leading to (3Z)‐3‐alkylidenepyrrol‐1‐ones

β‐Bromo‐α,β‐unsaturated amides are coupled and cyclized with terminal alkynes in DMF at 110 °C in the presence of a catalytic amount of CuI and amino acid along with a base to give the corresponding (3Z)‐3‐alkylidenepyrrol‐1‐ones in moderate to good yields. Copyright © 2013 John Wiley & Sons, Ltd.     

Copper‐catalyzed homo‐ and cross‐coupling reactions of terminal alkynes in ethyl lactate

The bio‐based chemical ethyl lactate (EL) has been discovered to be an excellent medium for the Glaser‐type homo‐ and cross‐coupling reactions of terminal alkynes. Good to excellent yields of conjugate diynes have been obtained under ligand‐free and mild heating conditions in the presence of CuI and molecular oxygen. Copyright © 2014 John Wiley & Sons, Ltd.     

CuI/8‐Hydroxyquinalidine Promoted N‐Arylation of Indole and Azoles

An efficient catalytic system of CuI/8‐hydroxyquinalidine was developed for the coupling of aryl iodides and indole as well as some azoles. The reaction could be carried out at 90°C under the condition of relatively low catalyst loading, affording various N‐arylindoles and N‐aryl azoles in good yields. The functionalized and hindered aryl iodides were suitable substrates for this transformation.     

Solvent Dependent Preparation of CuI Nanocrystals and the Catalysis in Sonogashira Coupling Reaction

Octahedral and rod‐like γ‐CuI nanocrystals have been fabricated by using a mild solution method in water, methanol and ethanol respectively. X‐ray diffraction (XRD) and field emission‐scanning electron microscopy (FE‐SEM) were used to characterize the product. The as‐synthesized CuI demonstrates higher activity for the Sonogashira cross‐coupling of 4‐iodoanisole and phenylacetylene.     

Amination Reactions of Aryl Halides with Nitrogen‐Containing Reagents Catalyzed by CuI in Ionic Liquid

CuI‐catalyzed coupling reactions of aryl iodides and electron‐deficient aryl bromides with nitrogen‐containing reagents, such as imidazole, benzimidazole, aliphatic primary and secondary amines, aniline, primary and secondary amides, in ionic liquid were developed. The reaction conditions involved the use of [Bmim][BF₄] as the solvent, potassium phosphate as the base, and CuI as the catalyst. The CuI and [Bmim][BF₄] could be recovered and recycled for five consecutive trials without significant loss of their activity.     

Cyano‐Schmittel Cyclization through Base‐Induced Propargyl‐Allenyl Isomerization: Highly Modular Synthesis of Pyridine‐Fused Aromatic Derivatives

The cyano‐Schmittel cyclization of in situ‐generated cyano‐allenes has been carried out. The DFT calculation results suggest that the diradical pathway plays a major role in this cyclization. The reactions can be conveniently performed in a one‐pot manner through cascade Sonogashira coupling of terminal cyano‐ynes with organic halides, followed by base‐promoted propargyl‐allenyl isomerization/cyclization, leading to an efficient access to pyridine‐fused polycyclic architectures. In particular, a large variety of aryl or heteroaryl rings such as furans, thiophenes and pyridines can be incorporated into the follow‐up cyano‐Diels–Alder reactions, highlighting the great synthetic utility of this chemistry.     

The Sonogashira Coupling of Polymer‐Supported Propargylamine with Aryl Iodides

The Sonogashira coupling reaction of polymer‐supported propargylamine (=prop‐2‐yn‐1‐amine) with aryl iodides in the presence of the [Pd(PPh₃)₂]Cl₂/CuI catalyst system produces 3‐arylprop‐1‐yn‐1‐amines smoothly at room temperature (Scheme). When propargylamine is attached on Wang resin through a carbamate linker, the common problems with amino functionality in palladium‐catalyzed couplings are overcome. The arylpropynamines are cleaved from the polymer with CF₃COOH and converted into chromatographically easily separable acetamides. Our solid‐phase method opens a new pathway toward precursors of pharmacologically interesting arylpropynamines and arylpropanamines.     

Hydroarylation of 2‐Aryloxybut‐1‐en‐3‐ynes via Pd/Acid‐Catalyzed C−H Bond Activation: A Concise Synthesis of 2,3‐Bismethylene‐2,3‐dihydrobenzofurans

An intramolecular exo ‐hydroarylation of 2‐aryloxy‐1,4‐disilylbut‐1‐en‐3‐ynes via ortho ‐C−H bond activation under palladium(0) and acid catalysis was found to give 2,3‐bis(silylmethylidene)‐2,3‐dihydrobenzofurans. The two silyl groups present probably promoted the reaction and played a key role in stabilizing the diene moiety in the product. The products readily led to functionalized condensed cycles by a Diels–Alder reaction.     

Sonochemical Synthesis of 1,4‐Disubstituted 1,2,3‐Triazoles in Aqueous Medium

An ultrasound‐accelerated fast and efficient three‐component reaction for the regioselective synthesis of l,4‐disubstituted 1,2,3‐triazoles using different alkyl and allyl halides, terminal alkynes, and sodium azide in water at room temperature has been developed using CuI as catalyst. Ultrasonication dramatically decreases the reaction times.     

Syntheses,Structures, and Catalytic Activities of Copper(I) Complexes with the Ligand 2(4,5‐Diphenyl‐1H‐imidazol‐2‐yl)­pyridine

Two copper(I) complexes of compositions [Cu(HL)I]₂ · EtOH ( 1 ) and [Cu(HL)₃]I · MeOH ( 2 ) were synthesized via the reactions of HL [HL = 2(4,5‐diphenyl‐1H‐imidazol‐2‐yl)pyridine] and CuI in EtOH and MeOH, respectively, under solvothermal conditions. The complexes were characterized by X‐ray single crystal diffraction, IR spectroscopy, and elemental analysis. Compounds 1 and 2 are catalytically active towards ketalization reaction, giving various ketals under mild conditions.     

Synthesis of 1H,7H,12bH‐Pyrano[3′,4′: 5,6]pyrano[3,4‐c][1]benzopyran‐1‐one via Domino Knoevenagel/Hetero‐Diels?Alder Reaction with Theoretical Investigations

The CuI‐catalyzed intramolecular oxa‐Diels? Alder reaction of 2‐(prop‐2‐yn‐1‐yloxy)benzaldehydes as unactivated terminal alkynes with 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one is described. The reaction proceeds with remarkable chemoselectivity to yield pyranones 3 (Scheme 1). A theoretical investigation of the reaction in terms of HOMO? LUMO interactions in the gas phase is also reported. The reaction could be regarded as an inverse‐electron‐demand Diels? Alder cycloaddition. The theoretical results are in high agreement with the experimental evidences.     

Alkoxyallene‐ynes: Selective Preparation of Bicyclo[5.3.0] Ring Systems Including a δ‐Alkoxy Cyclopentadienone

The development of an intramolecular rhodium(I)‐catalyzed Pauson–Khand reaction of alkoxyallene‐ynes with a proximal alkoxy group is reported. This reaction, in the presence of a [Rh(cycloocta‐1,5‐diene)Cl]₂/propane‐1,3‐diylbis(diphenylphosphane) system under a CO atmosphere, constitutes a powerful tool for selectively accessing carbo‐ and heterobicyclo[5.3.0] frameworks featuring an enol ether moiety. Through this procedure, a straightforward access to guaiane skeletons with a tertiary hydroxy group at the C10 position was achieved.