Ni‐Catalyzed Cross‐Coupling Reaction: The Direct Synthesis of Symmetrical Disulfanes from Aryl and Primary Alkyl Halides

A novel Ni‐catalyzed cross‐coupling reaction is introduced for the direct synthesis of diaryldisulfanes and dialkyldisulfanes from aryl halides and primary alkyl halides at normal atmospheric conditions, respectively. This one‐pot and domino protocol utilizes only 10 mol% of NiCl₂ as a catalyst and morpholin‐4‐ium morpholine‐4‐carbo‐dithioate as a new, stable, solid, and odorless sulfurating reagent in the presence of ethylene glycol as a cosolvent and bidentate ligand in dimethyl formamide (DMF) at 130°C with good to excellent yields and relatively short time reaction.     

Domino N‐/C‐Arylation via In Situ Generation of a Directing Group: Atom‐Efficient Arylation Using Diaryliodonium Salts

Both aryl components of diaryliodonium salts can be used in a domino one‐pot reaction via in situ generation of a directing group. A number of heterocycles undergo N‐arylation which is followed by ruthenium‐catalyzed C‐arylation. Notably the reaction extends well to unsymmetrical diaryliodonium salts with a number of highly selective examples shown.     

Ligand‐free,copper‐catalyzed,one‐pot,three‐component synthesis of novel 1,2,3‐triazole‐linked indoles in magnetized water

Magnetized water (MW) is used as a green and new solvent‐promoting medium for the one‐pot, three‐component synthesis of novel 1,2,3‐triazole‐linked indoles catalyzed by copper iodide. A broad range of 2‐aryl‐1‐(prop‐2‐ynyl)‐1H‐indole‐3‐carbaldehydes were reacted with alkyl halides and sodium azide via copper‐catalyzed azide–alkyne cycloaddition reactions in MW in the absence of any ligand. This method offers the advantages of short reaction times, green procedure, low cost, simple work‐up, quantitative reaction yields, and no need for any organic solvent.     

Commercial drug norfloxacin as a novel ligand for the copper‐catalyzed N‐arylation of imidazole with aryl halides

Norfloxacin was used as an efficient ligand for the CuBr‐catalyzed C‐N coupling reaction of imidazole and aryl halides. The protocol presented good functional group compatibility, permitting many aryl halides to react with imidazole to form the desired products in good to excellent yields.     

Pd(0)‐Catalyzed Tandem One‐Pot Reaction of Biphenyl Ketones/Aldehydes to the Corresponding Di‐substituted Aryl Olefins

Synthesis of di‐substituted aryl olefins via a Pd(0)‐catalyzed cross‐coupling reaction of biphenyl ketones/aldehydes, tosylhydrazide, and aryl bromides (or benzyl halides) was developed. This methodology was achieved by one‐pot two‐step reactions involving the preparation of N ‐tosylhydrazones by reacting tosylhydrazide with biphenyl ketones/aldehydes, followed by coupling with aryl bromides (or benzyl halides) in the presence of Pd(PPh₃ )₄ and lithium t ‐butoxide to produce various di‐substituted aryl olefins in moderate to good yields.     

Microwave-accelerated Synthesis of Some (±)-1-Aryl-5-chloroisochromans

Solventless one-pot synthesis of some new (±)-1-aryl-5-chloroisochromans by cyclocondensation of 2-(2-chlorophenyl)ethanol with aromatic aldehydes via an acid catalyzed oxa-Pictet-Spengler reaction under microwave irradiation is described.     

An Efficient Synthesis of Polyfunctionalized Indole Derivatives via Three‐component Domino Reaction Catalyzed by L‐Proline

A facile and efficient one‐pot procedure for the preparation of indeno[1,2‐b]indole derivatives via three‐component domino reaction of ninhydrin, enaminones, and malononitrile catalyzed by L‐proline is described. In this reaction, two rings and four bonds were formed by one‐pot.     

Stereoselective Synthesis of Trisubstituted Alkenes through Sequential Iron‐Catalyzed Reductive anti‐Carbozincation of Terminal Alkynes and Base‐Metal‐Catalyzed Negishi Cross‐Coupling

The stereoselective synthesis of trisubstituted alkenes is challenging. Here, we show that an iron‐catalyzed anti‐selective carbozincation of terminal alkynes can be combined with a base‐metal‐catalyzed cross‐coupling to prepare trisubstituted alkenes in a one‐pot reaction and with high regio‐ and stereocontrol. Cu‐, Ni‐, and Co‐based catalytic systems are developed for the coupling of sp‐, sp²‐, and sp³‐hybridized carbon electrophiles, respectively. The method encompasses a large substrate scope, as various alkynyl, aryl, alkenyl, acyl, and alkyl halides are suitable coupling partners. Compared with conventional carbometalation reactions of alkynes, the current method avoids pre‐made organometallic reagents and has a distinct stereoselectivity.     

CuBr/proline‐catalyzed cross‐coupling of unactivated benzene with aryl halides

Direct C? H arylation of unactivated benzene with aryl halides was achieved using a readily available copper catalyst. The reaction was carried out at 80 °C, using CuBr as catalyst, proline as ligand and t‐BuOK as base. This radical cross‐coupling reaction between unactivated benzene and aryl iodides proceeds via homolytic aromatic substitution and offers an efficient method for the synthesis of various biaryls in good to excellent yields. Copyright © 2015 John Wiley & Sons, Ltd.     

Rhodium(III)‐Catalyzed Directed C−H Amidation of N‐Nitrosoanilines and Subsequent Formation of 1,2‐Disubstituted Benzimidazoles

An efficient rhodium‐catalyzed direct C−H amidation of N ‐nitrosoanilines with 1,4,2‐dioxazol‐5‐ones as amidating agents has been developed. This method featured mild reaction conditions, a wide substrate scope and satisfactory yields. Besides, the amidated products could be readily converted to pharmaceutically valuable 1,2‐disubstituted benzimidazoles via an HCl‐mediated deprotection/cyclization process in one pot.     

Visible‐Light‐Promoted Nickel‐ and Organic‐Dye‐Cocatalyzed Formylation Reaction of Aryl Halides and Triflates and Vinyl Bromides with Diethoxyacetic Acid as a Formyl Equivalent

A simple formylation reaction of aryl halides, aryl triflates, and vinyl bromides under synergistic nickel‐ and organic‐dye‐mediated photoredox catalysis is reported. Distinct from widely used palladium‐catalyzed formylation processes, this reaction proceeds by a two‐step mechanistic sequence involving initial in situ generation of the diethoxymethyl radical from diethoxyacetic acid by a 4CzIPN‐mediated photoredox reaction. The formyl‐radical equivalent then undergoes nickel‐catalyzed substitution reactions with aryl halides and triflates and vinyl bromides to form the corresponding aldehyde products. Significantly, besides aryl bromides, less reactive aryl chlorides and triflates and vinyl halides serve as effective substrates for this process. Since the mild conditions involved in this reaction tolerate a plethora of functional groups, the process can be applied to the efficient preparation of diverse aromatic aldehydes.     

Synthesis of 3′,4′‐Diaryl‐4′H‐spiro[indoline‐3,5′‐[1′,2′,4′]oxadiazol]‐2‐ones via DMAP‐catalyzed Domino Reactions and Their Antibacterial Activity

A convenient and metal‐free DMAP‐catalyzed domino reaction of isatins, arylamines and hydroximoyl chlorides has been developed to achieve 1,3‐dipolar cycloaddition of imines into aryl nitrile oxides at ambient temperature. In this one‐pot transformation, a 1,2,4‐oxadiazole skeleton was efficiently formed. This methodology needs no extra additives and features wide substrate scope, good functional group tolerance and mild reaction conditions. A plausible mechanism for this process was proposed. Moreover, the antibacterial activities of the products were evaluated towards Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae using the Broth microdilution method.     

Facile Synthesis and Palladium‐Catalyzed Cross‐Coupling Reactions of 2,3‐Bis(pinacolatoboryl)‐1,3‐butadiene

Treatment of 1,1‐bis(pinacolatoboryl)ethene with an excess of 1‐bromo‐1‐lithioethene gave 2,3‐bis(pinacolatoboryl)‐1,3‐butadiene in high yield. Palladium‐catalyzed cross‐coupling of the resulting diborylbutadiene with aryl iodides took place smoothly in the presence of a catalytic amount of Pd(OAc)₂/PPh₃ and aqueous KOH to give 2,3‐diaryl‐1,3‐butadienes in good yields. The coupling reaction with commercially available 4‐acetoxyphenylmethyl chloride under the same conditions followed by hydrolysis of the acetyl groups gave anolignan B in a one‐pot manner. A variety of [3]‐ to [6]dendralenes were synthesized by palladium‐catalyzed coupling of the diene or 1,1‐bis(pinacolato)borylethene with alkenyl or dienyl halides, respectively, in good yields.     

A Mild and Simple One‐pot Synthesis of 2‐Substituted Benzimidazole Derivatives Using DDQ as an Efficient Oxidant at Room Temperature

A series of 2‐substituted benzimidazoles were prepared through one‐pot reaction of o‐phenylenediamine with various aryl aldehydes in the presence of 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) in acetonitrile as solvent at room temperature. The reactions were smoothly preceded in excellent yields and short reaction times with an easy work‐up. The pure benzimidazoles as products were confirmed and characterized by physical and spectral data.     

A Facile One‐Pot Route for the General Synthesis of Triazole Linked Chiral 2‐Substituted Benzimidazoles

One‐pot protocol for the synthesis of novel class of triazole linked 2‐sugar and 2‐aryl substituted benzimidazoles has been developed. The rapid and simple method involves copper (I) catalyzed simultaneous formation of benzimidazole and triazole rings at room temperature and in high yield.     

Transition‐Metal‐Catalyzed CS Bond Coupling Reaction

Sulfur‐containing molecules such as thioethers are commonly found in chemical biology, organic synthesis, and materials chemistry. While many reliable methods have been developed for preparing these compounds, harsh reaction conditions are usually required in the traditional methods. The transition metals have been applied in this field, and the palladium‐catalyzed coupling of thiols with aryl halides and pseudo halides is one of the most important methods in the synthesis of thioethers. Other metals have also been used for the same purpose. Here, we summarize recent efforts in metal‐catalyzed C? S bond cross‐coupling reactions, focusing especially on the coupling of thiols with aryl‐ and vinyl halides based on different metals.     

Palladium‐Catalyzed Direct Cross‐Coupling of Carboranyllithium with (Hetero)Aryl Halides

A palladium‐catalyzed direct C‐arylation reaction of readily available cage carboranyllithium reagents with aryl halides has been developed for the first time. This method is applicable to a wide range of aryl halide substrates including aryl iodides, aryl bromides, and heteroaromatic halides.     

Facile One‐Pot Synthesis of N‐Alkylated Benzimidazole and Benzotriazole from Carbonyl Compounds

An efficient one‐pot N‐alkylation of benzimidazole and benzotriazole from carbonyl compounds and tosylhydrazide has been accomplished via copper powder‐catalyzed N—H bond insertion affording N‐alkylated products in good yields. The reaction can tolerate a wide range of carbonyl compounds, such as aryl, alkyl, heterocyclic and α,β‐unsaturated ketones, and aldehydes.     

Regioselective Conversion of Arenes to N‐aryl‐1,2,3‐triazoles Using CH Borylation

A one‐pot protocol for the synthesis of N‐aryl 1,2,3‐triazoles from arenes by an iridium‐catalyzed C?H borylation/copper catalyzed azidation/click sequence is described. 1 mol % of Cu(OTf)₂ was found to efficiently catalyze both the azidation and the click reaction. The applicability of this method is demonstrated by the late‐stage chemoselective installation of 1,2,3‐triazole moiety into unactivated molecules of pharmaceutical importance.     

Easy One‐Pot Synthesis of 1‐Monosubstituted Aliphatic 1,2,3‐Triazoles from Aliphatic Halides,Sodium Azide and Propiolic Acid by a Click Cycloaddition/Decarboxylation Process

1‐Monosubstituted aliphatic 1,2,3‐triazoles were synthesized by a one‐pot reaction from aliphatic halides (Cl and Br), sodium azide and propiolic acid. The yields ranged from moderate to good. The reaction was easily carried out in DMF with Cs₂CO₃ at 100°C by copper‐catalyzed click cycloaddition/decarboxylation.