pi-Allylic C1-substitution in water with nitromethane using amphiphilic resin-supported palladium complexes

Nitromethane was safely applied as a C1 nucleophile for palladium-catalyzed pi-allylic substitution in water with amphiphilic PS-PEG resin-supported phosphine-palladium complexes. Catalytic asymmetric nitromethylation of cycloalkenyl esters was achieved in water as a single reaction medium under heterogeneous conditions using 5 mol % palladium of a PS-PEG resin-supported palladium-imidazoindolephosphine complex to give optically active (cycloalkenyl)nitromethanes with up to 98% ee.     

PS-PEG resin-supported palladium-MOP complexes. Application in asymmetric π-allylic reduction

Homochiral palladium complexes of polymeric 2′-, 6-, and 6′-anchored 2-diphenylphosphino-1,1′-binaphthyl (MOP) ligands were prepared on polystyrene-poly(ethylene glycol) (PS-PEG) resin. The PS-PEG resin-supported palladium-MOP complexes exhibited high catalytic activity, stereoselectivity (up to 80% ee), and recyclability (six times) in the asymmetric allylic reduction of 1-vinyl-1,2,3,4-tetrahydronaphth-1-yl benzoate to give 1-vinyl-1,2,3,4-tetrahydronaphthalene.     

Asymmetric π-allylic etherification of cycloalkenyl esters with phenols in water using a resin-supported chiral palladium complex

Catalytic asymmetric etherification of cycloalkenyl esters with phenolic nucleophiles was achieved in water as the sole reaction medium under heterogeneous conditions by using 2 mol % palladium of a PS-PEG resin-supported palladium–imidazoindolephosphine complex to give optically active aryl(cycloalkenyl) ethers with up to 94% ee.     

Development of an amphiphilic resin-dispersion of nanopalladium catalyst: Design,preparation, and its use in aquacatalytic hydrodechlorination and aerobic oxidation

An amphiphilic polystyrene-poly(ethylene glycol) (PS-PEG) resin-dispersion of nanoparticles of palladium was designed and prepared with a view toward use for catalysis in water. The amphiphilic PSPEG resin-dispersion of nanoparticles of palladium exhibited high catalytic performance in the hydrodechlorination of chloroarenes under aqueous conditions. The amphiphilic resin-supported nanopalladium particle also catalyzed alcohol oxidation, which is one of the most fundamental and important yet immature processes in organic chemistry, in water under an atmospheric pressure of oxygen gas to form aldehydes, ketones, and carboxylic acids.     

Heterogeneous Asymmetric Aquacatalysis with Polymer-Supported Palladium Complexes

Catalytic asymmetric organic transformations performed in aqueous media with immobilized chiral palladium and rhodium complexes are reviewed. Amphiphilic polystyrene-poly(ethylene glycol) graft co-polymer (PS-PEG) resin-supported MOP, boxax, BINAP, and an imidazoindole phosphine ligands were designed and prepared with a view to use them in asymmetric catalysis under aqueous and heterogeneous conditions. Several carbon–hydrogen, carbon–carbon, carbon–nitrogen, and carbon–oxygen bond forming reactions were achieved in water with high stereoselectivity and recyclability to meet the green chemical requirements.     

An Efficient and Practical Process for Pd/Cu Cocatalyzed Homocoupling Reaction of Terminal Alkynes Using Sodium Percarbonate as a Dual Reagent in Aqueous Media

A new process for the Pd/Cu co-catalyzed homocoupling reaction of terminal alkynes was developed. The reaction was carried out in aqueous media with sodium percarbonate as both a clean oxidant and a base. Meanwhile, a palladium complex immobilized on a synthetic PS-PEG400-PPh2 resin was used as the catalyst, which may be recovered by simple filtration and reused for several times with high activity.     

Polystyrene resin-supported CuI-cryptand 22 complex: a highly efficient and reusable catalyst for three-component synthesis of 1,4-disubstituted 1,2,3-triazoles under aerobic conditions in water

Polystyrene resin-supported copper(I) iodide-cryptand-22 complex (PS–C22–CuI) was synthesized and characterized by FT-IR, EDX, SEM, XPS, and TG-DTA analysis. This complex was found to be a highly active and robust heterogeneous catalyst for either three-component reaction of organic halides, sodium azide, and terminal alkynes, or the reaction of organic azides and alkynes to form 1,4-disubstituted 1,2,3-triazoles in good to excellent yields at room temperature, using water as the green solvent. The catalyst can be not only easily isolated from the final product by filtration but also reused without significant loss of catalytic activity.     

Enantioselective alkynylation of aromatic and heteroaromatic aldehydes catalyzed by resin-supported oxazolidine-titanium complexes

Highly enantioselective asymmetric addition of terminal alkynes to various aromatic and heteroaromatic aldehydes catalyzed by the readily available, low-cost, and reusable resin-supported oxazolidine 4 together with Ti(OⁱPr)₄ provides the chiral propargylic alcohols with good to excellent yields (up to 98%) and enantioselectivities (up to 95%). The immobilized catalyst can be recovered and used for five cycles.     

An amphiphilic resin-supported palladium catalyst for high-throughput cross-coupling in water

[reaction: see text] The Suzuki-Miyaura coupling of aryl halides (8 varieties) and aryl- or vinylboronic acids (12 varieties) took place in water in the presence of a palladium complex of an amphiphilic polystyrene-poly(ethylene glycol) copolymer resin-supported N-anchored 2-aza-1,3-bis(diphenylphosphino)propane ligand and potassium carbonate to give uniform and quantitative yields of the corresponding biaryls (96 varieties).     

Tandem "click" reactions at acetylene-terminated Si(100) monolayers

We demonstrate a simple method for coupling alkynes to alkynes. The method involves tandem azide-alkyne cycloaddition reactions ("click" chemistry) for the immobilization of 1-alkyne species onto an alkyne modified surface in a one-pot procedure. In the case presented, these reactions take place on a nonoxidized Si(100) surface although the approach is general for linking alkynes to alkynes. The applicability of the method in the preparation of electrically well-behaved functionalized surfaces is demonstrated by coupling an alkyne-tagged ferrocene species onto alkyne-terminated Si(100) surfaces. The utility of the approach in biotechnology is shown by constructing a DNA sensing interface by derivatization of the acetylenyl surface with commercially available alkyne-tagged oligonucleotides. Cyclic voltametry, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and X-ray reflectometry are used to characterize the coupling reactions and performance of the final modified surfaces. These data show that this synthetic protocol gives chemically well-defined, electronically well-behaved, and robust (bio)functionalized monolayers on silicon semiconducting surfaces.     

Synthesis of trans-Disubstituted Alkenes by Cobalt-Catalyzed Reductive Coupling of Terminal Alkynes with Activated Alkenes

A cobalt-catalyzed reductive coupling of terminal alkynes, RC?CH, with activated alkenes, R'CH?CH(2) , in the presence of zinc and water to give functionalized trans-disubstituted alkenes, RCH?CHCH(2) CH(2) R', is described. A variety of aromatic terminal alkynes underwent reductive coupling with activated alkenes including enones, acrylates, acrylonitrile, and vinyl sulfones in the presence of a CoCl(2) /P(OMe)(3) /Zn catalyst system to afford 1,2-trans-disubstituted alkenes with high regio- and stereoselectivity. Similarly, aliphatic terminal alkynes also efficiently participated in the coupling reaction with acrylates, enones, and vinyl sulfone, in the presence of the CoCl(2) /P(OPh)(3) /Zn system providing a mixture of 1,2-trans- and 1,1-disubstituted functionalized terminal alkene products in high yields. The scope of the reaction was also extended by the coupling of 1,3-enynes and acetylene gas with alkenes. Furthermore, a phosphine-free cobalt-catalyzed reductive coupling of terminal alkynes with enones, affording 1,2-trans-disubstituted alkenes as the major products in a high regioisomeric ratio, is demonstrated. In the reactions, less expensive and air-stable cobalt complexes, a mild reducing agent (Zn) and a simple hydrogen source (water) were used. A possible reaction mechanism involving a cobaltacyclopentene as the key intermediate is proposed.     

A general and regioselective synthesis of cyclopentenone derivatives through nickel(0)-mediated [3 + 2] cyclization of alkenyl Fischer carbene complexes and internal alkynes

A broad range of substituted 2-cyclopentenone derivatives 3-6 are synthesized by the nickel(0)-mediated [3 + 2] cyclization reaction of chromium alkenyl(methoxy)carbene complexes 1 and internal alkynes 2. The reaction takes place with complete regioselectivity with both unactivated alkynes and activated alkynes (electron-withdrawing and electron-donating substituted alkynes). Representative cycloadducts containing boron and tin substituents are further demonstrated to be active partners in classical Pd-catalyzed C-C coupling processes to allow the production of 2-aryl- and 2-alkynyl-substituted cyclopentenones 9-13.     

Rh(I)-catalyzed coupling cyclization of N-aryl trifluoroacetimidoyl chlorides with alkynes: one-pot synthesis of fluorinated quinolines

[reaction: see text]. Rh(I) complexes were found to catalyze the coupling cyclization of N-aryl trifluoroacetimidoyl chlorides with alkynes to afford 2-trifluoromethylated quinolines in good yields. Various alkynes were applied to this cyclization coupling with regioselectivity.     

Solvent-free cross-dehydrogenative coupling reactions under high speed ball-milling conditions applied to the synthesis of functionalized tetrahydroisoquinolines

Solvent-free reaction using a high-speed ball milling technique has been first applied to cross-dehydrogenative coupling (CDC) reactions between tetrahydroisoquinolines and three types of pronucleophiles such as nitroalkanes, alkynes, and indoles. All coupling products were obtained in good yields at short reaction times (no more than 40 min). When alkynes and indoles were used as pronucleophile, the reactions can be catalyzed efficiently by recoverable copper balls without any additional metal catalyst.     

Cobalt-catalyzed reductive coupling of activated alkenes with alkynes

Cobalt complex/Zn systems effectively catalyze the reductive coupling of activated alkenes with alkynes in the presence of water to give substituted alkenes with very high regio- and stereoselectivity in excellent yields. While the intermolecular reaction of acrylates, acrylonitriles, and vinyl sulfones with alkynes takes place in the presence of CoI2(PPh3)2/Zn, the reaction of enones and enals with alkynes requires the use of the CoI2(dppe)/Zn/ZnI2 system. The intramolecular reductive coupling of activated alkenes (enones, enals, acrylates, and acrylonitriles) with alkynes also works efficiently. Further a variety of cyclic lactones and lactams were prepared using this methodology. Possible mechanistic pathways are proposed based on a deuterium-labeling experiment carried out in the presence of D2O.     

超临界二氧化碳中PdCl2-CuCl2体系催化末端炔烃氧化偶联反应

研究了在超临界二氧化碳中实现PdCl₂-CuCl₂体系催化末端炔烃的氧化偶联反应, 研究结果表明: 催化剂、超临界二氧化碳及其共溶剂对反应结果有着重要的影响, 炔烃的取代基会影响末端炔烃在氧化偶联反应中的反应活性.     

Non-Sonogashira-type palladium-catalyzed coupling reactions of terminal alkynes assisted by silver(I) oxide or tetrabutylammonium fluoride

Palladium-catalyzed reaction of aryl and alkenyl halides with terminal alkynes in the presence of silver(I) oxide as an activator furnishes various arylated or alkenylated alkynes in good to excellent yields. The similar coupling reaction is also found to proceed using tetrabutylammonium fluoride (TBAF) or tetrabutylammonium hydroxide (TBAOH) as an activator.     

Rhodium(III)-catalyzed oxidative coupling of 5-aryl-1H-pyrazoles with alkynes and acrylates

[RhCp*Cl(2)](2)-catalyzed oxidative coupling of 5-aryl-1H-pyrazoles with alkynes and acrylates has been achieved using Cu(OAc)(2) as an oxidant. Coupling with alkynes afforded six-membered azacycles as a result of C-C and C-N coupling. Coupling with acrylates followed a process of diolefination and a subsequent aza-Michael cyclization.     

One-pot synthetic routes to multiply substituted indene derivatives by hydrolysis of zirconocene-mediated intermolecular coupling reactions of aromatic ketones and alkynes

Two one-pot multicomponent synthetic methods for highly substituted indenes are described. The intermolecular coupling of aromatic ketones with alkynes on low-valent zirconocene species generates oxazirconacyclopentenes, which upon hydrolysis with 20% HCl for 3 h afforded indene derivatives in good to excellent yields. Similarly, the pair-selective coupling of two identical or different alkynes bearing at least one aromatic substituent formed zirconacyclopentadienes. Quenching of the reaction mixture with concentrated H(2)SO(4) also results in the formation of highly substituted indenes in high yields.     

第5/6副族高价过渡金属氯化物的有机反应

从制备化学的角度, 对包括作者本人的研究工作在内的由第5/6副族高价过渡金属氯化物参加的有机反应进行了综述. 内容包括以下几个方面: (1)烷烃、烯烃和炔烃与第5/6副族高价过渡金属氯化物的卤化反应; (2)作为Lewis 酸催化的反应; (3)烯烃歧化反应及炔烃的聚合反应; (4) MoCl₅参与的芳烃氧化偶合反应; (5)硫醚化及扩环反应.