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Aryl alkene

Mechanistic studies show that the arylation of alkenes proceeds via the palladation of aromatic compounds to form a rr-aryl-Pd bond (261), into which insertion of alkene takes place to form 262. The final step is i3-elimina-tion to form the arylated alkenes 259 and Pd(0). [Pg.56]

Dibrom-1 -aryl-alkane Cu2CIj 1-Aryl-alkene s. Bd. V/l b, S. 202... [Pg.523]

Hydroboration of acyclic and cyclic aryl alkenes with (Bpin) (1.1 equiv.) in the presence of NaO Bn (1-100 mol%) and MeOH (2 equiv.) is catalysed by [CuCl(NHC)], (0.5-5 mol%) NHC = Dries, SDries and ICy, and proceeds with very good conversions and regioselectivity (Scheme 2.11). [Pg.41]

Scheme 2.14 Copper-catalysed intermolecular hydroamination of electron-deficient aryl alkenes... Scheme 2.14 Copper-catalysed intermolecular hydroamination of electron-deficient aryl alkenes...
Many chiral diphosphine ligands have been evaluated with regard to inducing enantioselectivity in the course of the hydroformylation reaction [25,26]. However, a real breakthrough occurred in 1993 with the discovery of the BI-NAPHOS ligand by Takaya and Nozaki [65]. This was the first efficient and rather general catalyst for the enantioselective hydroformylation of several classes of alkenes, such as aryl alkenes, 1-heteroatom-functionalized alkenes, and substituted 1,3-dienes, and is still a benchmark in this area [66,67]. But still a major problem in this field is the simultaneous control of enantio-... [Pg.158]

The major problem remains control of regioselectivity in favor of the branched regioisomer. While aryl alkenes as well as heteroatom-substituted alkenes favor the chiral branched isomer, for aliphatic alkenes such an intrinsic element of regiocontrol is not available. As a matter of fact branched-selective and asymmetric hydroformylation of aliphatic alkenes stands as an unsolved problem. In this respect regio- and enantioselective hydroformy-... [Pg.161]

R = allyl, alkyl, alkenyl, alkynyl, aryl, etc. R = aryl, alken ... [Pg.328]

Arbuzova, S.N., Gusarova, N.K., Malysheva, S.F., Brandsma, L., Albanov, A.I., and Trofimov, B.A., Reaction of red phosphorus with electrophiles in super-basic systems. Part 8. Reaction of red phosphorus and phosphine with aryl alkenes, Zh. Obshch. Khim., 66, 56, 1996. [Pg.39]

An enantioselective imino-ene reaction was developed by Lectka to provide ct-amino acid derivatives.27 Aryl alkenes (cr-methyl styrene, tetralene), aliphatic alkenes (methylene cyclohexane), and heteroatom-containing enes, all gave high yields and high ee s of the homoallylic amides (Equation (17)). The mechanism of this reaction has been proposed to proceed through a concerted pathway. This mechanism is evidenced by a large kinetic isotope effect observed in the transfer of H(D). [Pg.564]

The second part of the theory, which is a logical consequence of the first, is that monomers that have more than one basic site, e.g., an aromatic ring or an oxygen atom, can form more than one type of complex with the carbenium ion this idea was first proposed by Plesch (1990) in the context of chemically initiated polymerizations. It helps to explain why aryl alkenes and alkyl vinyl ethers polymerize more slowly than isobutene and cyclopentadiene. The reason is that all the complexes formed by the alkyl alkenes are propagators, whereas for the aryl alkenes and vinyl ethers only a fraction of the population of complexes can propagate. [Pg.386]

This expresses quantitatively by how much the rate-constants calculated on the basis of (40) for aryl alkenes and VE by the original investigators could be underestimated, and this effect must account-at least in part-for the great differences in the recorded in Table 1. [Pg.535]

Ligand 19 was found to be highly selective for the hydrogenation of 1-aryl, I -alkyl alkenes, and ligand 18b was found to be selective for 1-aryl, I -hindered aryl alkenes (Table 7). [Pg.58]

Despite the very low number of examples describing effective iridium-based asymmetric catalysts, there are some which deserve to be mentioned at this point. The preparation of hybrid NHC—oxazoUne ligands, allowed Burgess and coworkers to prepare Ir(l) complexes for the asymmetric hydrogenation of aryl alkenes (Scheme 3.19) [43]. These catalysts are among the most efficient in terms of yield and asymmetric inductions for this reaction. [Pg.51]

The same authors recently described the synthesis of similar rhodium-complexed dendrimers supported on a resin having both interior and exterior functional groups. These were tested as catalysts for the hydroformylation of aryl alkenes and vinyl esters (52). The results show that the reactions proceeded with high selectivity for the branched aldehydes, with excellent yields, even up to the tenth cycle. The hydroformylation experiments were carried out with first- and a second-generation rhodium-complexed dendrimers as catalysts, with a mixture of 34.5 bar of CO and 34.5 bar of H2 in dichloromethane at room temperature. Each catalyst was easily recovered by simple filtration and was reusable for at least six more cycles without... [Pg.118]

T. Allmendinger, R. Fujimoto, F. Gasparini, W. Schilling, Y. Satoh, ot-Fluoro-benzyl-phosphonates as reagents for the preparation of 1-fluoro-1-aryl alkenes and a-fluor-ostilbenes, Chimia 58 (2004) 133-137. [Pg.733]

It is interesting that NADH is also required as a stoichiometric co-factor in enzymatic oxygenation processes. In a detailed study of styrene monooxygenase (StyA), Andreas Schmid of the ETH/Zurich showed (J. Am. Chem. Soc. 125 8209,2003) that Cp Rh(bpy)(H 0)fc in combination with sodium formate served effectively to regenerate the NADH. Using this combination, epoxidation of aryl alkenes such as 6, 8 and 10 proceeded in high enantiomeric... [Pg.135]

Ti(BINOL). [ n-BuLi, PhSiHj trisubsti tuted aryl alkenes IACS 115 12569 (1993)... [Pg.9]

Houben-Weyl, Methoden der Organischen Chemie, 4th ed, Vol V/lb (alkenes, cycloalkenes, aryl alkenes), G. Thieme, Stuttgart (1972)... [Pg.217]

Normally, the most practical vinyl substitutions are achieved by use of the oxidative additions of organic bromides, iodides, diazonium salts or triflates to palladium(0)-phosphine complexes in situ. The organic halide, diazonium salt or triflate, an alkene, a base to neutralize the acid formed and a catalytic amount of a palladium(II) salt, usually in conjunction with a triarylphosphine, are the usual reactants at about 25-100 C. This method is useful for reactions of aryl, heterocyclic and vinyl derviatives. Acid chlorides also react, usually yielding decarbonylated products, although there are a few exceptions. Likewise, arylsulfonyl chlorides lose sulfur dioxide and form arylated alkenes. Aryl chlorides have been reacted successfully in a few instances but only with the most reactive alkenes and usually under more vigorous conditions. Benzyl iodide, bromide and chloride will benzylate alkenes but other alkyl halides generally do not alkylate alkenes by this procedure. [Pg.835]


See other pages where Aryl alkene is mentioned: [Pg.213]    [Pg.1488]    [Pg.1658]    [Pg.278]    [Pg.220]    [Pg.27]    [Pg.719]    [Pg.56]    [Pg.260]    [Pg.111]    [Pg.39]    [Pg.349]    [Pg.350]    [Pg.352]    [Pg.504]    [Pg.522]    [Pg.526]    [Pg.416]    [Pg.6]    [Pg.141]    [Pg.133]    [Pg.19]    [Pg.193]    [Pg.363]    [Pg.394]    [Pg.403]    [Pg.1279]    [Pg.1213]    [Pg.2542]   
See also in sourсe #XX -- [ Pg.530 ]




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