• Optically active cinchona alkaloid was anchored onto mesoporous SBA-16 silica and the as-prepared complex was used as a heterogeneous chiral ligand of osmium tetraoxide for the asymmetric dihydroxylation of olefins. (hindawi.com)
  • Cinchona alkaloid-based osmium complexes are harmless and known to be the most effective chiral catalysts for AD reactions in terms of both reactivity and enantioselectivity [ 15 - 18 ]. (hindawi.com)
  • In connection with our ongoing project that deals with the catalytic potential of the cinchona-alkaloid-derived amides,[17-19] we became interested in examining the reaction of allenoates with imines in the presence of a chiral tertiary amine catalyst. (docme.ru)
  • Shi, Z. Process for preparation of chiral cycloalkane derivatives by asymmetric cyclization. (sustc.edu.cn)
  • Weinstock, Chiral Michael Addition Methyl Vinyl Ketone Addi- tion Catalyzed by Cinchona Alkaloid Derivatives, J. Natl. (lolimoli.ru)
  • Since a relative short period (about 50 years) chemist have also used these alkaloids as chiral catalyst for a wide variety of asymmetric transformations. (worldwidescience.org)
  • As a class of versatile catalysts for asymmetric synthesis, cinchona alkaloids and their derivatives can catalyze an amazing array of synthetically important reactions, providing access to chiral products of high enantiopurity [32,33] . (beilstein-journals.org)
  • In connection with our studies on selective fluoroalkylation reactions, herein we disclose the first example of catalytic enantioselective difluoromethylation reaction of aromatic aldehydes with Me 3 SiCF 2 SO 2 Ph or PhSO 2 CF 2 H in the presence of a cinchona alkaloid-based chiral quaternary ammonium salt. (beilstein-journals.org)
  • Using a Cinchona alkaloid-derived squaramide as the catalyst, the tandem reaction proceeded smoothly under mild conditions and afforded a range of F3C-containing chiral polycyclic dihydroquinazolinones with excellent results (up to 99% yield, all cases >20 : 1 dr, up to 99% ee). (bvsalud.org)
  • The first catalytic asymmetric bromonium ion-induced polyene cyclization has been achieved by using a chiral BINOL-derived thiophosphoramide catalyst and 1,3-dibromo-5,5-dimethylhydantoin as an electrophilic bromine source. (imperial.ac.uk)
  • Walsh, P. J. Synthesis of Benzofuran Derivatives through Cascade Radical Cyclization/Intermolecular Coupling of 2-Azaallyl s. (upenn.edu)
  • Our paper describing the use of Cinchona alkaloids as nucleophilic Cl-transfer catalysts for asymmetric a-chlorination reactions has been accepted for publication in the European Journal of Organic Chemistry. (jku.at)
  • In the second part of the fellowship, a mutually compatible and cooperative combination of copper (I) triflate and bifunctional 9-amino (9-deoxy) epicinchona-derived urea compounds for the enantioselective Conia-ene cyclization of alkyne tethered b-ketoester substrates was developed. (europa.eu)
  • Cinchona Alkaloid Amide Catalyzed Enantioselective Formal [2+2]Cycloadditions of Allenoates and Imines Synthesis of 2 4-Disubstituted Azetidines. (docme.ru)
  • Enantioselective double michael addition/cyclization with an oxygen-centered nucleophile as the first step in a concise synthesis of natural (+)-asteriscanolide. (mcg.law)
  • Chua, P. J. Process for highly enantioselective Michael addition of 1,3-diaryl-1,3-propanedione to nitroolefins using using cinchona alkaloids as recyclable organocatalysts. (sustc.edu.cn)
  • The enantioselective extraction of aqueous 3,5-dinitrobenzoyl-R,S-leucine (A(R,S)) by a cinchona alkaloid extractant (C) in 1,2-dichloroethane was studied at room temperature (294 K) in a batch system for a range of intake concentrations (10(-4)-10(-3) mol/L) and pH values (3.8-6.6). (worldwidescience.org)
  • Enantioselective synthesis of pyrano[2,3-c]pyrrole via an organocatalytic [4 + 2] cyclization reaction of dioxopyrrolidines and azlactones (Electronic supplementary information (ES. (uni-hamburg.de)
  • Wynberg's report from 1977 that natural cinchona alkaloids catalyze the asymmetric conjugate addition of aromatic thiols to cycloalkenones is a landmark discovery in hydrogen bonding organocatalysis. (hammersmithendocrinology.org)
  • The new model rationalizes the stereoselective outcome of Wynberg's reaction and provides a new, general model for asymmetric cinchona organocatalysis. (hammersmithendocrinology.org)
  • Herein, we described the synthesis of SBA-16 supported cinchona alkaloid ligand and tested it for the osmium catalyzed AD reaction of olefins to diols, a key reaction in organic synthesis. (hindawi.com)
  • This thesis describes the application of novel and existing cinchona-alkaloid catalyzed Interrupted Feist Bènary (IFB) reactions towards the total synthesis of two biologically active targets: the anticancer compound (-)-rocaglamide and the benzo[b]indeno[2,1-d]furanone Picornavirus inhibitor tetracyclic antiviral-1 (TA-1). (wesleyan.edu)
  • Mlynarski, J., „A Concise Organocatalytic Synthesis of 3-deoxy-2-Ulosonic Acids via Cinchona Alkaloid-Promoted Aldol Reaction of Pyruvate" , Eur. (edu.pl)
  • 2.3 Asymmetric phase transfer catalysed alkylation of glycine imines using cinchona alkaloid derived quaternary ammonium salts (Barry Lygo and Benjamin I. Andrews). (nhbs.com)
  • Zanarini, ,L. 4 In contrast, the acid- or forex kuniya info process in 3 utki forex tion selectively forms tetrahydrofuran dervivatives 3 (n 1), as expected based on Baldwins Rules for cyclization reactions. (lolimoli.ru)
  • Cinchona alkaloids cat catalyze reactions, such as shown in Reaction 1. (comporgchem.com)
  • As shown in Scheme 1 , enzymatic control of whether guanidinium enolate 1 undergoes an intramolecular conjugate addition or a protonation dictates whether 1 is an intermediate for the biosynthesis of polycyclic guanidine alkaloids ptilocaulin or batzelladine K. In this paper, we wish to describe the development of a small-molecule catalyst system to achieve high stereoselectivity and control of chemoselectivity of two different reaction intermediates. (pnas.org)
  • In alkaloid biosynthesis, there are a limited number of enzymes that can catalyze an aromatic electrophilic substitution. (ubc.ca)
  • This is the first committed step in the biosynthesis of the benzylisoquinoline alkaloids that include morphine and codeine. (ubc.ca)
  • The synthase catalyzes the first committed step in the ergot alkaloid biosynthesis. (ubc.ca)
  • Our interest in the field led us to prepare SBA-16 silica-supported biscinchona alkaloid for osmium-catalyzed asymmetric dihydroxylation (AD) of olefins. (hindawi.com)
  • Modified cinchona alkaloid ligands: Improved selectivities in the osmium tetroxide catalyzed asymmetric dihydroxylation (AD) of terminal olefins. (mcg.law)
  • An organocatalytic asymmetric sequential allylic alkylation-cyclization of Morita-Baylis-Hillman carbonates and 3-hydroxyoxindoles. (edu.sa)
  • Based on previous work on the IFB reaction, pyriminidinyl bis-quinidine cinchona alkaloids catalysts were screened in hopes of producing the IFB product with synthetically useful enantioselectivities. (wesleyan.edu)
  • The ordered mesoporous SBA-16 silica was found to be a valuable support for the cinchona alkaloid liganded osmium catalyst system which is frequently used in chemical industries and research laboratories for olefin functionalization. (hindawi.com)
  • While these studies were not able to distinguish between the two proposed cyclization pathways, they were successful in shedding light on the mechanism in other ways. (wikipedia.org)
  • This supports a mechanism involving a two-step cyclization of the putative iminium ion intermediate that does not proceed via a spirocyclic intermediate. (ubc.ca)
  • Chapter 7 describes the development of an effective grinding device for the grinding of herbal samples such as Cinchona barks. (worldwidescience.org)
  • 1,3-Dipolar cycloaddition and palladium(II)-catalyzed alkoxycarbonylation were leveraged for the construction of the hexacyclic scaffold en route to both natural products. (hammersmithendocrinology.org)
  • The use of these barks in medicines against "fevers" in Europe in the 17th century made the exploitation of cinchonas of Peru a highly productive process, and those cinchona trees became menaced. (worldwidescience.org)