Recent Developments and New Perspectives in the Heck Reaction

Cabri, Walter; Candiani, Ilaria

doi:10.1021/ar00049a001

Cited by 946 publications

(406 citation statements)

References 47 publications

Supporting

Mentioning

385

Contrasting

Unclassified

Order By: Relevance

“…24 The method proved to have applicability as varying R with electron-withdrawing and electron-donating groups (Scheme 1) diverse compounds could be synthesized in a straightforward procedure. The electronic delocalization induced by the methoxy groups at the 6 and 7-positions allows the coumarin to have a distinctive behavior for the Heck coupling reactions which enhances this work and make it very useful for this particular family of compounds.…”

Section: Resultsmentioning

confidence: 99%

“…The Heck catalytic system involving CH 3 CO 2 Ag as sequestering agent of halide, indicates a cationic mechanism for the coordinationinsertion step, i.e., the coordination of 3 should take place via dissociation of the anionic ligand (X -), and a cationic palladium(II) complex 6 is formed (Scheme 3). 24 The reactivity of the cationic complex 5 depends on the charge density of the unsaturated system reacting faster with electron rich ones which is the case of the vinyl coumarin 3 (poor π-acceptors and good σ-donors). The faster formation of 6 will account for the success of the methodology.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

An efficient methodology for the synthesis of 3-styryl coumarins

Martins¹,

Branco²,

Pereira³

2012

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

Foi desenvolvida a arilação de Heck, regiosseletiva e altamente eficiente, de 3-vinil-6,7-dimetoxicumarina, para a obtenção de 3-estiril cumarinas com bons a excelentes rendimentos. O aumento da conjugação nos produtos sintetizados reflete na absorvância, revelando todos desvios batocrômicos pronunciados e efeitos hipercrômicos.Regioselective and highly efficient Heck arylation of 3-vinyl-6,7-dimethoxycoumarin has been developed to afford 3-styryl coumarins in good to very high yields. The increase in conjugation reflects on the absorbance of the synthesized compounds revealing all pronounced bathochromic shifts and hyperchromic effects.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

An efficient methodology for the synthesis of 3-styryl coumarins

Martins¹,

Branco²,

Pereira³

2012

J. Braz. Chem. Soc.

View full text Add to dashboard Cite

show abstract

“…In disinfection and synthetic applications higher concentrations of Br Ϫ may be used, thereby employing the maximal turnover of the mutant. As an example of the latter, we intend to couple alkaline halogenation of aromatic compounds by the mutant to a palladium-catalyzed Heck reaction (39,40), which only occurs effectively at alkaline pH. In this manner the halide is recycled thus leading to elimination of salt waste.…”

Section: Discussionmentioning

confidence: 99%

Laboratory-evolved Vanadium Chloroperoxidase Exhibits 100-Fold Higher Halogenating Activity at Alkaline pH

Hasan

Renirie

Kerkman³

et al. 2006

Journal of Biological Chemistry

View full text Add to dashboard Cite

Directed evolution was performed on vanadium chloroperoxidase from the fungus Curvularia inaequalis to increase its brominating activity at a mildly alkaline pH for industrial and synthetic applications and to further understand its mechanism. After successful expression of the enzyme in Escherichia coli, two rounds of screening and selection, saturation mutagenesis of a "hot spot," and rational recombination, a triple mutant (P395D/L241V/T343A) was obtained that showed a 100-fold increase in activity at pH 8 (k cat ‫؍‬ 100 s ؊1 ). The increased K m values for Br ؊ (3.1 mM) and H 2 O 2 (16 M) are smaller than those found for vanadium bromoperoxidases that are reasonably active at this pH. In addition the brominating activity at pH 5 was increased by a factor of 6 (k cat ‫؍‬ 575 s ؊1 ), and the chlorinating activity at pH 5 was increased by a factor of 2 (k cat ‫؍‬ 36 s ؊1 ), yielding the "best" vanadium haloperoxidase known thus far. The mutations are in the first and second coordination sphere of the vanadate cofactor, and the catalytic effects suggest that fine tuning of residues Lys-353 and Phe-397, along with addition of negative charge or removal of positive charge near one of the vanadate oxygens, is very important. Lys-353 and Phe-397 were previously assigned to be essential in peroxide activation and halide binding. Analysis of the catalytic parameters of the mutant vanadium bromoperoxidase from the seaweed Ascophyllum nodosum also adds fuel to the discussion regarding factors governing the halide specificity of vanadium haloperoxidases. This study presents the first example of directed evolution of a vanadium enzyme.Haloperoxidases catalyze the oxidation of halides to hypohalous acids (see Equation 1), an industrially interesting reaction; these enzymes can be used to halogenate various organic compounds (1, 2) (see Equation 2). In addition they may provide an alternative biocide in antifouling applications (3-5) or may be used as a component in disinfectants and in detergent formulations for bleaching purposes (6 -8). Equations 1 and 2 illustrate the reactions occuring.where X is clorine, bromine, or iodine, and A is an organic nucleophilic acceptor.Presently two classes of enzymes are known that efficiently catalyze the oxidation of a halide by hydrogen peroxide, the vanadium haloperoxidases and the heme peroxidases. The heme peroxidases have a significant disadvantage of rapid inactivation during turnover because of an oxidative reaction of the heme group with the peroxide substrate and the formed hypohalous acids. Vanadium haloperoxidases (VHPOs), 2 which contain vanadate (VO 4 3Ϫ ) as a prosthetic group, do not suffer from this disadvantage (9); in addition they are much more resistant toward heat, detergent, and solvent denaturation (10). The major drawback of all haloperoxidases including the stable VHPOs is that they are mainly active at mildly acidic pH values, whereas for many applications activity at mildly alkaline pH values is required. An example of this is their potential use as an antif...

show abstract

“…O rganopalladium complexes [ArPd(R 3 P) 2 X] (X ϭ halogen) play important roles as key intermediates in numerous Pd-catalyzed reactions of aryl halides, such as the Heck arylation of olefins, the Kharasch-Fields, Stille, Suzuki, and Sonogashira coupling reactions, and many nucleophilic displacement and carbonylation reactions [1][2][3][4][5][6]. These complexes provide an attractive point into various Pd-catalyzed cross-couplings, due to both enhanced catalytic activity relative to zerovalent PdL n complexes and ease of handling.…”

mentioning

confidence: 99%

“…These complexes provide an attractive point into various Pd-catalyzed cross-couplings, due to both enhanced catalytic activity relative to zerovalent PdL n complexes and ease of handling. However, the aryl-aryl interchange reaction of [ArPd(R 3 P) 2 X] usually resulted in the formation of phosphine-derived by-products in catalytic and stoichiometric cross-coupling reactions, which has been investigated by Cheng, Novak, and Grushin etc. [7][8][9][10][11][12].…”

mentioning

confidence: 99%

ESI-FTICR-MS studies on gas phase fragmentation reactions of ArPd(PPh₃)₂I complexes

Qiu

Liao

Guo

et al. 2006

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Gas-phase fragmentation reactions of [ArPd(PPh 3 ) 2 ]ϩ were studied by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The results of sustained off-resonance irradiation collision-activated dissociation (SORI-CAD) experiments provide detailed insights into mechanisms for the gas-phase fragmentation reactions of these complex ions. The POC bond cleavage mediated by palladium is investigated in the gas phase. There are two competitive fragmentation pathways for the complex ions [ArPd( ϩ (Ar ϭ p-OCH 3 -C 6 H 4 , p-CH 3 -C 6 H 4 , p-tBu-C 6 H 4 , p-NH 2 -C 6 H 4 , p-COCH 3 -C 6 H 4 , p-F-C 6 H 4 ), and the third pathway involves loss of one molecule of benzene and one PPh 3 ligand. The electronic effect and steric effect of the aryl groups also exhibit different influences on the fragmentation pathways. (J Am Soc Mass Spectrom 2006, 17, 1582-1589

show abstract

Recent Developments and New Perspectives in the Heck Reaction

Cited by 946 publications

References 47 publications

An efficient methodology for the synthesis of 3-styryl coumarins

An efficient methodology for the synthesis of 3-styryl coumarins

Laboratory-evolved Vanadium Chloroperoxidase Exhibits 100-Fold Higher Halogenating Activity at Alkaline pH

ESI-FTICR-MS studies on gas phase fragmentation reactions of ArPd(PPh₃)₂I complexes

Contact Info

Product

Resources

About

Recent Developments and New Perspectives in the Heck Reaction

Cited by 946 publications

References 47 publications

An efficient methodology for the synthesis of 3-styryl coumarins

An efficient methodology for the synthesis of 3-styryl coumarins

Laboratory-evolved Vanadium Chloroperoxidase Exhibits 100-Fold Higher Halogenating Activity at Alkaline pH

ESI-FTICR-MS studies on gas phase fragmentation reactions of ArPd(PPh3)2I complexes

Contact Info

Product

Resources

About

ESI-FTICR-MS studies on gas phase fragmentation reactions of ArPd(PPh₃)₂I complexes