Efficient Synthesis of Dialkyl (2Z)‐2‐[(E)‐1‐Aryl‐2‐(3‐arylquinoxalin‐2‐yl)ethenyl]but‐2‐enedioates

The reaction of dialkyl acetylenedicarboxylates 4 with 1‐aryl‐2‐[(3‐arylquinoxalin‐2(1H)‐ylidene)ethanones 3 in the presence of Ph₃P leads to dialkyl (2Z)‐2‐[(E)‐1‐aryl‐2‐(3‐arylquinoxalin‐2‐yl)ethenyl]but‐2‐enedioates 1 in good yields.     

Synthesis of 2‐Aryl‐2,3‐dihydro‐3‐sulfanyl‐1H‐isoindol‐1‐ones by Pummerer‐Type Cyclization of N‐Aryl‐2‐(sulfinylmethyl)benzamides

An efficient method for the synthesis of 2‐aryl‐2,3‐dihydro‐3‐sulfanyl‐1H‐isoindol‐1‐ones 1 via Pummerer‐type cyclization of N‐aryl‐2‐(sulfinylmethyl)benzamides 2 is described. Thus, treatment of these sulfinyl‐benzamides 2 , easily prepared from 2‐(bromomethyl)benzoates 3 in three steps, with Ac₂O at ca. 100° resulted in the formation of the desired isoindolones 1 in generally good yields.     

Phenyliodine(III) Bis(Trifluoroacetate) Mediated Synthesis of 2‐Aryl‐1,2‐Benzisothiazol‐3(2H)‐Ones in Ionic Liquid

Treatment of N‐aryl‐2‐(benzylthio)benzamides with phenyliodine(III) bis(trifluoroacetate) containing trifluoroacetic acid resulted in an interrupted Pummerer‐type reaction in ionic liquid 1‐n‐butyl‐3‐methylimidazolium hexafluorophosphate, [bmim][PF₆] to give 2‐aryl‐1,2‐benzisothiazol‐3(2H)‐ones rather than the normal Pummerer‐type products.     

Palladium‐Catalyzed Amination of Aryl Sulfides with Anilines

A combination of a palladium–NHC catalyst and potassium hexamethyldisilazide enables the amination of aryl sulfides with anilines to afford a wide variety of diarylamines. The reaction conditions are versatile enough for the reaction of even bulky ortho‐substituted aryl sulfides. This amination can be applied to the modular synthesis of N‐aryl carbazoles from the corresponding ortho‐bromothioanisoles. As aryl sulfoxides undergo extended Pummerer reactions to afford ortho‐substituted aryl sulfides, the Pummerer products are thus useful substrates for the amination to culminate in efficient syntheses of a 2‐anilinobenzothiophene and an indole as proof‐of‐principle of the utility of the extended Pummerer reaction/amination cascade.     

Unexpected Ritter Reaction During Acid‐Promoted 1,3‐Dithiol‐2‐one Formation

A series of aryl‐substituted 1,3‐dithiol‐2‐ones was prepared by the Bhattacharya? Hortmann cyclization method. Unexpectedly, a Ritter reaction occurred during the acid‐catalyzed cyclization at the cyano group of the aryl substituents and 1,3‐dithiol‐2‐ones bearing a carboxy or a carboxamide group could be selectively obtained (see 1 and 2a in Scheme 1). The formation of the acid or the amide functionality was temperature‐dependent so that the one or the other group could be introduced selectively by modifying the reaction temperature.     

Chiral Ammonium Betaine‐Catalyzed Highly Stereoselective Aza‐Henry Reaction of α‐Aryl Nitromethanes with Aromatic N‐Boc Imines

A highly stereoselective aza‐Henry reaction of α‐aryl nitromethanes with aromatic N‐Boc imines was established by using C₁‐symmetric chiral ammonium betaine as a bifunctional organic base catalyst. Various substituted aryl groups for both imines and nitromethanes were tolerated in the reaction, and a series of precursors for the synthesis of unsymmetrical anti‐1,2‐diaryl ethylenediamines was provided.     

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.     

Transition‐Metal‐Free α‐Arylation of Enolizable Aryl Ketones and Mechanistic Evidence for a Radical Process

The α‐arylation of enolizable aryl ketones can be carried out with aryl halides under transition‐metal‐free conditions using KOtBu in DMF. The α‐aryl ketones thus obtained can be used for step‐ and cost‐economic syntheses of fused heterocycles and Tamoxifen. Mechanistic studies demonstrate the synergetic role of base and solvent for the initiation of the radical process.     

The Reaction of (N‐Isocyanimino)triphenylphosphorane with Biacetyl in the Presence of Aromatic Carboxylic Acids: Efficient One‐Pot Three‐Component Reaction for the Synthesis of 3‐(5‐Aryl‐1,3,4‐oxadiazol‐2‐yl)‐3‐hydroxybutan‐2‐one Derivatives

Reactions of biacetyl (=butane‐2,3‐dione) with (N‐isocyanimino)triphenylphosphorane in the presence of aromatic carboxylic acids proceed smoothly at room temperature and under neutral conditions to afford 3‐(5‐aryl‐1,3,4‐oxadiazol‐2‐yl)‐3‐hydroxybutan‐2‐one derivatives in high yields.     

A Facile One‐Pot Three‐Component Synthesis of 5‐(Trifluoromethyl)‐4,7‐dihydro‐[1,2,4]‐triazolo[1,5‐a]pyrimidine Derivatives in Ionic Liquid

An efficient one‐pot synthesis of 5‐(trifluoromethyl)‐4,7‐dihydro‐7‐aryl‐[1,2,4]triazolo[1,5‐a]pyrimidine derivatives was performed via the reaction of aryl aldehyde, 3‐amino‐1,2,4‐triazole and ethyl 4,4,4‐trifluoro‐3‐oxobutanoate or 4,4,4‐trifluoro‐1‐phenylbutane‐1,3‐dione in ionic liquid. This method has the advantages of short synthetic route, operational simplicities, mild reaction conditions, high yields and eco‐friendliness.     

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.     

One‐Pot Synthesis of 3‐Acetyl‐2‐aryl‐3,4‐dihydroquinazolines from N‐[2‐(Azidomethyl)phenyl]benzamides Utilizing Intramolecular Aza‐Wittig Reaction

A new and convenient method for the preparation of 3,4‐dihydroquinazolines 5 with aryl and Ac groups at C(2) and N(3), respectively, has been developed. The key sequence is the formation of aza‐phosphorane intermediates by the reaction of N‐[2‐(azidomethyl)phenyl]benzamides 1 with Ph₃P, followed by intramolecular aza‐Wittig reaction and 3‐acetylation, which can be conducted in one‐pot.     

An Efficient Synthesis of N‐Substituted‐3‐aryl‐3‐(2‐hydroxy‐4,4‐dimethyl‐6‐oxocyclohex‐1‐enyl)propanamides by Four‐component Reaction in Aqueous Medium

A mild and efficient synthesis of N‐substituted‐3‐aryl‐3‐(2‐hydroxy‐4,4‐dimethyl‐6‐oxocyclohex‐1‐enyl)propanamides via four‐component reaction of an aldehyde, amine, Meldrum's acid and 5,5‐dimethylcyclo‐hexane‐1,3‐dione in the presence of benzyltriethylammonium chloride (TEBAC) in aqueous medium is described. This method has the advantages of accessible starting materials, good yields, mild reaction conditions and eco‐friendliness.     

Radical Cyclization/ipso‐1,4‐Aryl Migration Cascade: Asymmetric Synthesis of 3,3‐Difluoro‐2‐propanoylbicyclo[3.3.0]octanes

A novel method for the asymmetric synthesis of 3,3‐difluoro‐2‐propanoylbicyclo‐[3.3.0]octanes involves an unprecedented intramolecular radical cyclization/ipso‐1,4‐aryl migration cascade.     

Keteniminium‐Driven Umpolung Difunctionalization of Ynamides

A three‐component Pd‐catalyzed coupling of ynamides, aryl diazonium salts, and aryl boronic acids for the synthesis of novel triaryl‐substituted enamides is described. This transformation represents the first example of an umpolung regioselective unsymmetrical syn‐1,2‐diarylation/aryl‐olefination of ynamides. The aryl moieties of the diazonium salt (electrophile) and boronic acid (nucleophile) are explicitly incorporated in the electrophilic α‐ and nucleophilic β‐position, respectively, of the ynamide, resulting in a single isomer of the N‐bearing tetrasubstituted olefin. The scope is broad (68 examples), showing excellent functional‐group tolerance. DFT calculations substantiate the rationale of the mechanistic cycle and the regioselectivity. The chemoselectivity and synthetic potential of the enamide products were also studied.     

Asymmetric Proline‐Catalyzed Addition of Aldehydes to 3H‐Indol‐3‐ones: Enantioselective Synthesis of 2,3‐Dihydro‐1H‐indol‐3‐ones with Quaternary Stereogenic Centers

The proline‐catalyzed addition of various aliphatic aldehydes to sterically hindered 2‐aryl‐substituted 3H‐indol‐3‐ones affords 2,2‐disubstituted 2,3‐dihydro‐1H‐indol‐3‐one derivatives with excellent enantioselectivities. In addition, the synthesis of a chiral derivative, (S)‐2‐(2‐bromophenyl)‐2,3‐dihydro‐2‐(2‐hydroxyethyl)‐1H‐indol‐3‐one, which can be used as an intermediate for the preparation of the natural product hinckdentine A was accomplished with a high level of enantioselectivity.     

由邻苯二胺合成苯并咪唑、喹喔啉以及1-H-2,3－二氢1,5-苯并氮杂卓

A series of benzo-fused heteroaromatic compounds with 5-, 6- and 7-membered tings, such as benzimidazole,quinoxaline and 1H-1,5-benzodiazepine derivatives, were synthesized through condensation reaction of o-pheny1-enediamine with ary1 aldehydes or ketones. The experimental conditions were carefully examined, and the products were characterized by ^1H NMR, ^13C NMR, MS, IR and elemental analyses. In addition, the structure of a benzodiazaepine derivative with 7-membered ring was confirmed by single crystal X-ray diffraction analysis.     

Reversible Dehalogenation in On‐Surface Aryl–Aryl Coupling

In the emerging field of on‐surface synthesis, dehalogenative aryl–aryl coupling is unarguably the most prominent tool for the fabrication of covalently bonded carbon‐based nanomaterials. Despite its importance, the reaction kinetics are still poorly understood. Here we present a comprehensive temperature‐programmed x‐ray photoelectron spectroscopy investigation of reaction kinetics and energetics in the prototypical on‐surface dehalogenative polymerization of 4,4′′‐dibromo‐p‐terphenyl into poly(para‐phenylene) on two coinage metal surfaces, Cu(111) and Au(111). We find clear evidence for reversible dehalogenation on Au(111), which is inhibited on Cu(111) owing to the formation of organometallic intermediates. The incorporation of reversible dehalogenation in the reaction rate equations leads to excellent agreement with experimental data and allows extracting the relevant energy barriers. Our findings deepen the mechanistic understanding and call for its reassessment for surface‐confined aryl–aryl coupling on the most frequently used metal substrates.     

Stereoselective Synthesis of Aryl Cyclopentene Scaffolds by Heck–Matsuda Desymmetrization of 3‐Cyclopentenol

A new enantioselective Heck–Matsuda desymmetrization reaction was accomplished by using 3‐cyclopentenol to produce chiral five‐membered 4‐aryl cyclopentenol scaffolds in good yields and high ee’s, together with some 3‐aryl‐cyclopentanones as minor products. Mechanistically, the hydroxyl group of 3‐cyclopentenol acts as a directing group and is responsible for the cis‐ arrangement in the formation of the 4‐aryl‐cyclopentenols.     

在催化体系可回收和无配体条件下溴化四丁基铵中钯催化卤代芳烃与芳基硼酸的Suzuki-Miyaura交叉偶联反应

我们发展一种在催化体系可回收和无配体条件下溴化四丁基铵（TBAB）中钯催化卤代芳烃与芳基硼酸的Suzuki-Miyaura交叉偶联反应方法。我们发现水的量对反应有很大的影响。当水的用量为1 %（质量比）时,反应的结果最好。在3 mol%的醋酸钯和1.5 g的TBAB（含1%的水）,一系列卤代芳烃与芳基硼酸的顺利地发生Suzuki-Miyaura交叉偶联反应,得到中等及良好的产率。而且在溴代芳烃和活泼的氯代芳烃的交叉反应中,Pd(OAc)2/TBAB催化体系可以回收重复使用多次,并且催化活性基本不变。