An efficient synthesis of optically pure (S)-2-functionalized 1,2,3,4-tetrahydroquinoline

Using a copper-catalyzed coupling reaction of amino acid and aryl halide, followed by intramolecular cyclization of N-aryl-1-hydroxyl-3-propylamines under the Swern’s condition as the key steps, (S)-2-hydroxymethyl-1,2,3,4-tetrahydroquinoline was synthesized as an example of optically pure 2-functionalized 1,2,3,4-tetrahydroquinolines.     

Copper-catalyzed N-arylation of sulfonamides with aryl bromides and iodides using microwave heating

The copper-catalyzed N-arylation of sulfonamides with a variety of aryl bromides and iodides using microwave heating is described.     

Copper/oxalohydrazide/ketone catalyzed synthesis of primary arylamines via coupling of aryl halides with aqueous ammonia in water

The coupling reaction of aryl halides with aqueous ammonia was catalyzed by copper/oxalohydrazide/ketone system in water to yield primary arylamines without inert atmosphere. This method was fast and facile. The coupling reaction proceeded at 90 °C for 20-80 min, or at room temperature for a prolonged reaction time. A variety of aryl bromides and iodides were found to be applicable to this three-component catalytic system, which afforded good to excellent isolated yields.     

Palladium-catalysed intramolecular enolate O-arylation and thio-enolate S-arylation: synthesis of benzo[b]furans and benzo[b]thiophenes

Enolates derived from α-(ortho-haloaryl)-substituted ketones undergo palladium-catalysed C-O bond formation to deliver benzofuran products in good yield. A catalyst generated from Pd₂(dba)₃ and the ligand DPEphos effects the key bond formation to deliver a variety of substituted products from both cyclic and acyclic precursors. The analogous thio-ketones undergo C-S bond formation using identical reaction conditions and are converted to benzothiophene products. A cascade sequence that produces the required α-aryl ketones in situ has also been developed, although the substrate scope is more restricted.     

水相中底物促进的铜催化氨基醇N-芳基化反应

在水相体系中, 利用铜催化一系列氨基醇类底物(1.2 mmol)与碘代芳烃(1.0 mmol)进行N-芳基化反应. 由于氨基醇具有双齿配位及相转移催化能力, 该反应利用氨基醇类底物自身的促进作用, 在不使用外加配体与相转移催化剂的温和条件下以高收率获得了氨基醇N-芳基化产物(64%-93%).     

Facile synthesis of perfluoroalkylated fluorenes via a one-pot two-step three-component process

The efficient synthesis of perfluoroalkyl-substituted fluorenes directly from indenones, malononitrile and methyl perfluoroalk-2-ynoates via a one-pot two-step three-component cascade process is reported. Up to 12 examples of indenones with various substituents were converted into their corresponding functionalized fluorene derivatives in good to excellent yields.     

Iron/copper-catalyzed C-C cross-coupling of aryl iodides with terminal alkynes

Synergic effect of iron and copper salts as catalysts for the Sonogashira-Hagihara cross-couplings of aryl iodides with terminal alkynes is demonstrated. High yields of cross-coupled products are obtained under conditions that are smoother than those using only CuI as catalyst. Furthermore no expensive or/and toxic ligand is required.     

Copper-mediated direct arylation of benzoazoles with aryl iodides

The direct arylation of 1,3-benzoazole compounds with aryl iodides is effectively promoted by CuI with use of PPh₃ and Na₂CO₃ or K₃PO₄ as ligand and base, respectively, in DMF or DMSO to produce the corresponding 2-arylated products with good yields.     

Facile synthesis of Koser's reagent and derivatives from iodine or aryl iodides

The first one-pot synthesis of neutral and electron-rich [hydroxy(tosyloxy)iodo]arenes (HTIBs) from iodine and arenes is presented, thereby avoiding the need for expensive iodine(III) precursors. A large set of HTIBs, including a polyfluorinated analogue, can be obtained from the corresponding aryl iodide under the same conditions. The reaction proceeds under mild conditions, without excess reagents, and is fast and high-yielding. Together, the two presented routes give access to a wide range of HTIBs, which are useful reagents in a variety of synthetic transformations.     

Fe-based metal-organic frameworks for the synthesis of N-arylsulfonamides via the reactions of sodium arylsulfinates or arylsulfonyl chlorides with nitroarenes in water

A newly developed chemoselective reaction of sodium arylsulfinates or arylsulfonyl chlorides with nitroarenes has been disclosed. The chemistry, in which non-toxic water and recyclable iron-based metal-organic frameworks are employed as the solvent and catalyst, respectively, provides an efficient approach for the generation of N-arylsulfonamides, which are widely present in biologically active compounds and drugs, rendering this methodology attractive to both synthetic and medicinal chemistry.     

Substrate-promoted ligand-free CuI catalyzed S-arylation of 2-mercaptobenzothiazoles with aryl iodides in water

A green and efficient method has been developed for the cross-coupling of 2-mercaptobenzothiazoles with aryl iodides in water. The reactions proceeded smoothly under ligand-free conditions in the presence of TBAB to give the corresponding products in good yields. The protocol showed good tolerance toward a variety of functional groups. A substrate-promoted mechanism for this catalytic reaction has been proposed.     

Facile synthesis of thiadiazolo [2,3-b] quinazoline derivatives via the Japp-Klingemann Reaction

Diazotized anathranilic acid and its methyl ester react with substituted α-thiocyanatoacetoacetanilides3a–c to give in both cases the corresponding thiadiazolo [2,3-b] quinazolines6a–c, respectively. A mechanism is proposed and it is substantiated by synthesis of6a from N-(2-car?yphenyl)-C-phenylcarbamoyl hydrazidoyl chloride8a or its N-(2-methoxycarbonylcarbonylphenyl) analogue8d.     

Copper-catalyzed synthesis of 2-sulfenylindoles from indoline-2-thiones and aryl iodides

A novel and efficient method for synthesis of 2-sulfenylindole via copper-catalyzed coupling reaction of indoline-2-thiones with aryl iodides has been developed. A series of N-substituted and N-free 2-sulfenylindole were obtained in high yields. Furthermore, the method was employed to synthesis of benzothieno[2,3-b]indoles from indoline-2-thiones with 1,2-diiodobenzene in the presence of CuI and Pd(OAc)₂ as catalysts.     

A route to fluorocontaining N,S-heterocycles via octafluoro-2,3-epoxybutane

The reaction of octafluoro-2,3-epoxybutane 1 with 2-aminothiophenol gave three kinds of novel fluorocontaining N,S-heterocyclic compounds depending on the solvent nature: 2,3-bis(trifluoromethyl)-3,4-dihydro-2H-1,4-benzothiazin-2-ol 2, 2-trifluoromethyl-2-[1-(2-aminophenylthio)-2,2,2-trifluoroethyl]-1,3-benzothiazolidine 6 and 5a,11a-bis(trifluoromethyl)-5a,6,11a,12-tetrahydro-5,11-dithia-6,12-diazanaphthacene 5. Use of the toluene, dioxane, tetrahydrofuran, acetonitrile and dimethoxyethane gave the unexpected dihydrobenzothiazine 2 (RS,SR > RR,SS) in good to moderate yields. In dimethylsulfoxide and N,N-dimethylacetamide, unusual cyclization occurred resulting in benzothiazolidine 6 (RS,SR/RR,SS ∼ 1:1) in moderate yields. Formation of minor 1,1,1,3,4,4,4-heptafluoro-3-(2-aminophenylthio)-2,2-dihydroxybutane 4 which was converted into bis(benzothiazine) 5 was observed in all solvents tested with the exception of toluene and dioxane. The molecular structure of the RS,SR-diastereomer of dihydrobenzothiazine 2, bis(benzothiazine) 5 and the RS,SR-diastereomer of benzothiazolidine 6 has been established by X-ray crystallography.     

Copper catalyzed N-arylation between aryl halides and nitriles in water: an efficient tandem synthesis of benzanilides

A series of benzanilide compounds were synthesized through copper-catalyzed tandem reactions. With the assistance of ionic liquid as phase transfer catalyst, aryl halides, and nitriles underwent a hydrolysis/coupling pathway to form benzanilides in water. Advantages of this reaction include the use of water as the environmental friendly solvent, short reaction time, and the tolerance of various functional groups. A proposed mechanism based on control experiments is also presented.     

A practical synthesis of aryl sulfones via cross-coupling of sulfonyl hydrazides with aryltriazenes using copper/ionic liquid combination

A new and efficient approach adopting copper-catalyzed cross-coupling of sulfonyl hydrazides with aryltriazenes has been developed to synthesize aryl sulfones using Brønsted acidic ionic liquid as promoter under ambient conditions. The process employs stable and easy to handle reacting partners, and is endowed with broad substrate scope.     

Direct synthesis of N-arylamides via the coupling of aryl diazonium tetrafluoroborates and nitriles under transition-metal-free conditions

The direct synthesis of N-arylamides via the coupling of aryl diazonium tetrafluoroborates and nitriles under transition-metal-free conditions has been developed. The reported protocol is practical and represents an efficient method to produce functionalized amides in moderate to good yields.     

Mild copper-catalyzed N-arylation of azaheterocycles with aryl halides

A highly efficient copper(I)-catalyzed N-arylation of azaheterocycles with various aryl halides is reported. The N-arylation reaction can be carried out using as low as 0.5 mol % of (Cu(I)OTf)₂·PhH and 1.0 mol % of 4,7-dichloro-1,10-phenanthroline as the ligand. Furthermore, cheap and stable copper precursors like Cu(I)I and Cu(II)(OAc)₂·H₂O and the cheap and mild base K₂CO₃ can be used.     

Transition metal free one pot synthesis of aryl carboxylic acids via dehomologative oxidation of styrenes

Iodine/NaOH-catalyzed one-pot dehomologative oxidation of styrenes to aryl carboxylic acids has been reported. A wide range of carboxylic acids are obtained using iodine (I₂) as a catalyst, tert-butyl hydroperoxide (TBHP) as an oxidant and sodium hydroxide (NaOH) as a base. This reliable conversion involves dehomologation of styrene to aromatic aldehyde which on subsequent oxidation affords aryl carboxylic acid. This protocol was used for gram-scale synthesis as it is free from chromatographic purification. This is the first report for the oxidative transformation of styrenes into aryl carboxylic acids under transition metal-free conditions.     

Copper-catalyzed direct preparation of diaryl sulfides from aryl iodides using potassium thiocyanate as a sulfur transfer reagent

A method for direct preparation of diaryl sulfides from aryl iodides using potassium thiocyanate as a sulfur-transfer agent is reported. A catalyst system comprising of a simple copper salt, tetrabutylammonium bromide as a phase-transfer agent and water as the solvent is used. Microwave heating at 200 °C for 60 min allows for the conversion of a range of aryl iodides to the corresponding diaryl sulfides.