Fe(0)催化三氯乙酸烯丙酯的环化反应研究

通过对Fe(O)催化烯烃自由基环化反应的研究，发现以Fe(O)为催化剂催化三氯 乙酸烯丙酯分子内自由基环化反应可以高化学选择性得到五元环内酯产物，反应中 不需加入配体。和大多数自由基反应一样，反应温度与催化剂用量对该反应的转化 率和产率有着很大的影响。     

Nickel(0)-Catalyzed Three-Component Connection Reaction of Dimethylzinc, 1,3-Dienes, and Carbonyl Compounds

Linear 1:1:1 coupling of dimethylzinc, 1,3-dienes, and carbonyl compounds in this order is facilitated by catalytic amounts of [Ni(acac)(2)] to give (E)-3-hexen-1-ols in good yields under mild conditions [Eq. (a)]. Increasing steric hindrance at the carbonyl group favors formation of the 1:2:1 adduct, and this is the sole product when the carbonyl compound is acetone. acac=acetylacetonate.     

Palladium(0)-Catalyzed Intermolecular Asymmetric Cascade Dearomatization Reaction of Indoles with Propargyl Carbonate

An intermolecular asymmetric cascade dearomatization reaction of indole derivatives with propargyl carbonate was developed. The challenges associated with both the chemoselectivity between the carbon and nitrogen nucleophile and the enantioselective control during the formation of an all-carbon quaternary stereogenic center were well addressed by a Pd catalytic system derived from the Feringa ligand. A series of enantioenriched multiply substituted fused indolenines were provided in good yields (71–86 %) with excellent enantioselectivity (91–96 % ee) and chemoselectivity ( 3 / 4 >19:1 in most cases).     

Efficient Palladium(0)-Catalyzed Synthesis of Alkenyl 1-Thioglycosides and Thiodisaccharides

ABSTRACT

Unsaturated thiodisaccharides are obtained in good yields by alkylation of ethyl α-O-?²-glycosides, having a leaving group at C-4, with various thiocarbohydrates in the presence of a catalytic amount of palladium(0). The reaction is regio- and stereospecific for the α-erythro enoside, and only stereospecific in the case of the α-threo enoside, alkylation occurring at C-4 and C-2. In all cases, only the β-anomer is formed.     

3-戊烯腈在零价镍催化体系中的平衡反应

在探索3-戊烯腈氢氰化合成己二腈反应的机理过程中,发现3-戊烯腈在零价镍体系中可能同时存在多个平衡反应,在不外加氰化氢条件下,3-戊烯腈可以生成甲基戊二腈和己二腈.采用零价镍、膦配体和无水ZnCl2组成的催化体系研究了该反应过程,考察了反应温度和配体的影响,并采用原位红外对反应进行监测,提出了可能的反应机理.     

Selective Homogeneous Palladium(0)-Catalyzed Hydrogenation of Alkynes to (Z)-Alkenes

Zero-valent palladium precatalysts containing rigid bidentate bis(arylimino)acenaphthene ligands (shown schematically) facilitate the highly stereoselective homogeneous catalytic hydrogenation of alkynes to (Z)-alkenes. Internal, terminal, aryl-substituted, and cyclic alkynes are suitable substrates, as are some enynes, which are chemoselectively hydrogenated to dienes. E=CO(2)Me; R(1), R(2)=4-OCH(3), 4-CH(3), 2,6-(CH(3))(2).     

Highly Porous Amidoximed Carbon Nanofibers Supported Palladium(0) Nanoparticle Catalyzed Heck Reaction

Highly porous amidoximed carbon nanofibers(AOCNFs), which were fabricated via a conventional electrospinning technique followed by chemically modification, impregnation-reduction and carbonization process, had been used for the immobilization of palladium nanoparticles(Pd NPs) catalyst. During the carbonization process, polystyrene(PS) was selectively decomposed from bicomponent fibers, generating porous fibers. Fourier transform infrared spectroscopy(FTIR) result revealed the functional groups on PAN-PS fibers(PAN=polyacrylonitrile), AOPAN-PS fibers and AOCNFs; scanning electron microscopy(SEM) was used to observe the morphology of all stages of nanofibers; transmission electron microscopy(TEM) result gave the structure of through-hole morphology clearly visible and the dispersion of Pd NPs on the surface of nanofibers; and X-ray photoelectron spectra(XPS) confirmed that Pd nanoparticles on the surface of AOCNFs was of the metallic state. Moreover, the as-prepared catalyst exhibited high catalytic activity and efficient recycle for Heck coupling reactions between iodobenzene and acrylates.     

Stereoselective Synthesis of Functionalized 1,3-Enynes through Recyclable Copper(I)-Catalyzed Three-Component Reaction of Terminal Alkynes,Diazoesters and Aldehydes

A highly efficient heterogeneous copper(I)-catalyzed three-component coupling of terminal alkynes, diazoesters and aldehydes has been achieved by using 10 mol% of copper(I) iodide complex [N,N-CuI-MCM-41] anchored on 2-aminoethylamino-modified mesoporous material MCM-41 as the catalyst under mild conditions, delivering a wide variety of 2-alkoxycarbonyl-substituted (E)-1,3-enynes in mostly good to high yields with excellent stereoselectivity. The heterogenized copper(I) complex can be facilely prepared from inexpensive reagents by using a simple procedure and exhibits a remarkably higher catalytic activity than CuI, and can be recycled more than ten times without a significant drop in its catalytic efficiency. This protocol represents the first example of heterogeneous copper-catalyzed stereoselective construction of functionalized 1,3-enynes from simple and commercially available starting materials.     

Effect of Hydrogen on Catalytic Coupling Reaction of Carbon Monoxide to Diethyl Oxalate

The kinetics of hydrolysis of tetrahydrozoline hydrochloride in aqueous solution at 353, 363 and 368 K in the pH-range from 2.00 to 12.20 has been investigated. The decomposition products have been investigated by HPLC. This revised version was published online in June 2006 with corrections to the Cover Date.     

Palladium(II)-Catalyzed Enantioselective Azidation of Unactivated Alkenes

The first Pd-catalyzed enantioselective azidation of unactivated alkenes has been established by using readily accessible 1-azido-1,2-benziodoxol-3(1H)-one (ABX) as an azidating reagent, which affords a wide variety of structurally diverse 3-N₃-substituted piperidines in good yields with excellent enantioselectivity. The reaction features good functional-group compatibility and mild reaction conditions. Notably, both an electrophilic azidating reagent and the sterically bulky chiral pyridinyl-oxazoline (Pyox) ligand are crucial to the successful reaction.     

钯催化一氧化碳、四氯化碳和1-辛烯的加成反应

在吡啶的存在下和不同的醇溶剂中 ,一氧化碳、四氯化碳和 1 -辛烯在钯催化下的加成反应能在较温和的条件下进行 ,反应生成共加成产物 2 - ( 2 ,2 ,2 -三氯乙基 )辛酸酯和简单加成产物 1 ,1 ,1 ,3-四氯壬烷     

Kinetics and Mechanism of a Reaction of Phenylacetylene with Carbon Monoxide and Butanol in Toluene Catalyzed by a Palladium(0) Complex in the Presence of Trifluoroacetic Acid and Triphenylphosphine

The reaction of phenylacetylene with CO and n-butanol in toluene (363 K) catalyzed by the Pd(dba)₂/m(CF₃COOH)/n(Ph₃P) system (dba is dibenzylideneacetone; 2 m 8; 10 n 30) is studied. The initial rate of the main product (butyl 2-phenylpropenoate) buildup is found to depend on the pressure of CO and the concentrations of reactants and system components. The state of the catalyst under reaction conditions is studied in situby IR spectroscopy. A kinetic model is developed based on the experimental results. This model corresponds to the mechanism that resembles the hydride mechanism in the type of main intermediates in the catalytic cycle.     

Cyclization-Carbonylation-Cyclization Coupling Reaction of Propargyl Ureas with Palladium(II)-Bisoxazoline Catalyst

The cyclization-carbonylation-cyclization coupling reaction (CCC-coupling reaction) of propargyl ureas catalyzed by Pd^II(box) complexes afforded symmetrical ketones bearing two 2-amino-2-oxazoline groups in good to moderate yields.