The Experts below are selected from a list of 552 Experts worldwide ranked by ideXlab platform

Scott G. Nelson - One of the best experts on this subject based on the ideXlab platform.

  • catalytic asymmetric Acyl Halide aldehyde cyclocondensation reaction
    Organic Syntheses, 2005
    Co-Authors: Scott G. Nelson, Paul M Mills
    Abstract:

    (S)-Valinol Triethylamine Trifluoromethanesulfonic anhydride (S)-N-Trifluoromethylsulfonyl-2-isopropylaziridine Benzylamine (2S,6S)-4-Benzyl-1,7-bis(trifluoromethylsulfonyl)-2,6-disopropyll-1,4,7-triazaheptane Disiopropylethylamine Trimethylaluminum Acetyl bromide Hydrocinnamaldehyde (4S)-4-(2-Phenethyl)oxetane-2-one Keywords: cyclocondensation; catalyst; asymmetric reaction; Acyl Halide; aldehyde; enantioenriched β-lactones; oxetanones; waste disposal

  • catalytic asymmetric Acyl Halide aldehyde cyclocondensation reactions of substituted ketenes
    ChemInform, 2004
    Co-Authors: Scott G. Nelson, Cheng Zhu, Xiaoqiang Shen
    Abstract:

    Catalytic asymmetric Acyl Halide−aldehyde cyclocondensation (AAC) reactions of alkyl-substituted ketenes with structurally diverse aldehydes provide cis-disubstituted β-lactones with high enantioselectivity. The AAC reactions utilize a novel Al(III)-triamine catalyst in which the metal's dynamic coordination geometry leads to a highly selective catalyst complex. These AAC reactions represent a functional solution to highly enantioselective substituted ester enolate aldol additions.

  • a de novo enantioselective total synthesis of laulimalide
    Journal of the American Chemical Society, 2002
    Co-Authors: Scott G. Nelson, Andrew J. Kassick, Wing S Cheung, Mark A. Hilfiker
    Abstract:

    An enantioselective total synthesis of the naturally occurring anticancer agent (−)-laulimalide is described. The synthesis is characterized by extensive use of new reaction methodologies based on catalytic asymmetric Acyl Halide−aldehyde cyclocondensation (AAC) reactions and transformations of the derived enantioenriched β-lactones. The synthesis also incorporates a unique allenylstannane glycal acetate alkylation and chemoselective ring-closing metathesis reaction.

  • catalytic asymmetric propionate aldol reactions via Acyl Halide aldehyde cyclocondensations
    Organic Letters, 2000
    Co-Authors: Scott G. Nelson, Zhonghui Wan
    Abstract:

    Catalyzed asymmetric Acyl Halide-aldehyde cyclocondensation (AAC) reactions afford highly enantiomerically enriched 3,4-disubstituted-2-oxetanones. These reactions constitute catalytic asymmetric propionate aldol additions. An optically active Al(III)-triamine complex (10 mol %) catalyzes the di(isopropyl)ethylamine-mediated cyclocondensation of propionyl bromide and a variety of aldehydes to afford beta-lactone adducts with uniformly high enantioselection (90 --> 98% ee), diastereoselection (74 --> 98% de), and chemical yields (78-90%). Lactone ring opening reveals that the enantiomerically enriched beta-lactones act as surrogates for syn propionate aldol adducts.

N. Zydowicz - One of the best experts on this subject based on the ideXlab platform.

  • Preparation of oily core polyamide microcapsules via interfacial polycondensation
    Polymer International, 2003
    Co-Authors: M l Soto-portas, J f Argillier, Françoise Méchin, N. Zydowicz
    Abstract:

    Microcapsules obtained by interfacial polycondensation froman original system based on the polyaddition of specific di- or polyamines and more classical Acyl chloride molecules were studied. The originality of the system lies in the fact that the encapsulated agent is the internal phase allowing its incorporation without an organic solvent, which is an advantage from the point of view of environmental protection. Once the optimal parameters of the emulsion were determined, the membrane formation was studied by optimizing the emulsification and reaction times in relation to simultaneous Acyl chloride hydrolysis. The microcapsules were obtained by interfacial polycondensation between an excess of amine functions (diamine and diethylenetriamine) and Acyl chloride (sebacoyl chloride and 1,3,5-benzene tricarbonyl trichloride) from an oil-in-water emulsion in the presence of 88%hydrolyzed poly(vinyl alcohol) as a surfactant. Various formulations in terms of COCl concentration, crosslinking agent concentration, excess of amine functions, emulsification and reaction times were prepared. The hydrolysis of Acyl Halide functions is the main parameter which influences the growth of the membrane. The increase in Acyl chloride function concentration allows compensation for that lost by hydrolysis, and increases the encapsulation yield to about 90%. The degree of crosslinking of the membrane was controlled in order to minimize the subsequent release of oil by the addition of trifunctional monomers. An optimal formulation was developed offering high encapsulation yield and optimal elastic behaviour. Almost spherical capsules, with a membrane thickness of approximately 500nm, relatively smooth internal walls and crumpled external walls, were observed by scanning electron microscopy.

Funge Hong - One of the best experts on this subject based on the ideXlab platform.

  • secondary phosphine oxides versatile ligands in transition metal catalyzed cross coupling reactions
    Coordination Chemistry Reviews, 2012
    Co-Authors: Tanveer Mahamadali Shaikh, Chiaming Weng, Funge Hong
    Abstract:

    Abstract This review describes the development in the use of secondary phosphine oxides ligands in transition-metal-catalyzed oxidative coupling reactions to the formation of C C, C N and C S bonds. Also the developments in the recent literature are highlighted in the areas of cycloaddition, coupling of Acyl Halide with organometallic reagents, oxidations and other reactions. The secondary phosphine oxides are known to exist in the tautomeric forms and are configurationally stable; this property enables a variety of useful transformations for accessing optically active organophosphorus compounds which are useful in the formation of C C bonds and asymmetric hydrogenation reactions. Finally, the mechanistic aspect employing DFT technique in these oxidative coupling reactions is described in this article.

Michal Szostak - One of the best experts on this subject based on the ideXlab platform.

  • Recent advances in Acyl suzuki cross-coupling
    Catalysts, 2019
    Co-Authors: Jonathan Buchspies, Michal Szostak
    Abstract:

    Acyl Suzuki cross-coupling involves the coupling of an organoboron reagent with an Acyl electrophile (Acyl Halide, anhydride, ester, amide). This review provides a timely overview of the very important advances that have recently taken place in the Acylative Suzuki cross-coupling. Particular emphasis is directed toward the type of Acyl electrophiles, catalyst systems and new cross-coupling partners. This review will be of value to synthetic chemists involved in this rapidly developing field of Suzuki cross-coupling as well as those interested in using Acylative Suzuki cross-coupling for the synthesis of ketones as a catalytic alternative to stoichiometric nucleophilic additions or Friedel-Crafts reactions.

Mark A. Hilfiker - One of the best experts on this subject based on the ideXlab platform.

  • a de novo enantioselective total synthesis of laulimalide
    Journal of the American Chemical Society, 2002
    Co-Authors: Scott G. Nelson, Andrew J. Kassick, Wing S Cheung, Mark A. Hilfiker
    Abstract:

    An enantioselective total synthesis of the naturally occurring anticancer agent (−)-laulimalide is described. The synthesis is characterized by extensive use of new reaction methodologies based on catalytic asymmetric Acyl Halide−aldehyde cyclocondensation (AAC) reactions and transformations of the derived enantioenriched β-lactones. The synthesis also incorporates a unique allenylstannane glycal acetate alkylation and chemoselective ring-closing metathesis reaction.