22461-89-8Relevant articles and documents
In search of new approaches to asymmetric conjugate addition: Screening studies on the use of [Zn(bpy*)X(R)] reagents and α,β- unsaturated amide Michael acceptors
Blake, Alexander J.,Giunta, Daniela,Jonathanss-SHANNON,Solinas, Maurizio,Walzer, Francesca,Woodward, Simon
, p. 1107 - 1121 (2007)
Conjugate additions of [Zn(bpy*)Cl(Et)] (bpy* = 4,4′-di-tert-butyl-2,2′-bipyridine) to cyclohex-2-en-1-one are promoted by ZnMe2 in 88% ee but in moderate yield under Cu I phosphoramidite catalysis. In the absence of ZnMe2 the [Zn(bpy*)Cl(Et)] is inactive indicating a Schlenk-type equilibrium. Other derivatives of [Zn(bpy*)Cl(R)] (R = Bu, 4-methylbenzyl), prepared in situ from [ZnCl(R)] and the bipyridine give low yields due to competing chloride abstraction. 13C NMR studies indicate facile organo-ligand exchange between [Zn(bpy*)(Et)2] and [Zn(bpy*)Cl2] complexes. In the presence of the bipyridine, [ZnBr(allyl)] disproportionates into [Zn(bpy*)Br2] and [Zn(bpy*)(allyl)2] species. In separate studies, simple (E)-MeCH=CHCONMeR (R = Me, OMe) α,β-unsaturated amides undergo asymmetric 1,4-addition of EtMgBr in 75-99% yield and 48-79% ee in the presence of the diphosphines JosiPhos or MeDuPhos and copper(I) sources.
1,4-Addition of diethylzinc to cyclohexenone catalyzed by CuOTf-sulfonamide combined system. Evidence supporting a concerted mechanism
Nakano, Keiji,Bessho, Yuhki,Kitamura, Masato
, p. 224 - 225 (2003)
Measurement of 12C/13C isotope effect in the Cu(I)/sulfonamide-catalyzed 1,4-addition of diethylzinc to 2-cyclohexenone implies that the reaction proceeds by a concerted mechanism, different to those so far reported for the conventio
Preparation of silane-grafted pellets: Silica bound reagents in a very convenient form
Timofte, Roxana S.,Woodward, Simon
, p. 39 - 42 (2004)
High surface area silica pellets are excellent supports for the preparation of silica supported reagents and solid-phase basal linkers through reaction with (RO)3Si(CH2)3FG (FG=NH 2, NHMe, Cl, NHC(=O)NH2/s
Diethylzinc: A chain-transfer agent in intermolecular radical additions. A parallel with triethylborane
Bertrand, Michele P.,Feray, Laurence,Nouguier, Robert,Perfetti
, p. 9189 - 9193 (1999)
In the presence of oxygen, diethylzinc can be used to promote radical additions to C=N bond containing radical acceptors and to enones. In these reactions, it plays at the same time the role of the initiator and the role of the chain-transfer reagent. A p
New phosphoramidite and phosphito-N chiral ligands based on 8-substituted quinolines and (S)-binaphthol; applications in the Cu-catalyzed enantioselective conjugate addition of diethylzinc to 2-cyclohexen-1-one
Arena, Carmela G.,Calabro, Gianpiero,Francio, Giancarlo,Faraone, Felice
, p. 2387 - 2392 (2000)
The copper(II)-catalyzed enantioselective conjugate addition of diethylzinc to 2-cyclohexen-1-one, in the presence of phosphoramidite and of phosphito-N chiral ligands, derived from 8-chloroquinoline or 8-hydroxyquinoline and (S)-4-chloro-3,5-dioxa-4-phos
Peptidic amidomonophosphane ligand for copper-catalyzed asymmetric conjugate addition of diorganozincs to cycloalkenones
Soeta, Takahiro,Selim, Khalid,Kuriyama, Masami,Tomioka, Kiyoshi
, p. 629 - 635 (2007)
Peptidic modification of (5)-2-[(diphenylphosphino)methyl]pyrrolidine gave a dipeptide-connected amidomonophosphane ligand for the highly efficient, copper-catalyzed asymmetric conjugate addition reaction of organozinc reagents with cycloalkenones, giving
Highly enantioselective catalytic conjugate addition and tandem conjugate addition-aldol reactions of organozinc reagents
Feringa, Ben L.,Pineschi, Mauro,Arnold, Leggy A.,Imbos, Rosalinde,De Vries, Andre H. M.
, p. 2620 - 2623 (1997)
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1,1′-binaphthyl-2,2′-diamine-based chiral phosphorous triamides: synthesis and application in asymmetric catalysis
Barta, Katalin,Eggenstein, Matthias,Hoelscher, Markus,Francio, Giancarlo,Leitner, Walter
, p. 6198 - 6204 (2009)
A set of chiral monodentate phosphorous triamldes (PTA) comprising 1, 1′-binaphthyl-2, 2′-diamlne as the common moiety have been synthesised. Electronic and steric tuning of the ligands was achieved by variation of the substituents at the diamine nitrogen
Chiral diphosphites derived from D-glucose in the copper-catalyzed conjugate addition of diethylzinc to cyclohexenone
Dieguez, Montserrat,Ruiz, Aurora,Claver, Carmen
, p. 2895 - 2900 (2001)
A series of diphosphite ligands 1-3 derived from readily available D-(+)-glucose and bisphenol or binaphthol derivatives have been applied as ligands in the Cu-catalyzed 1,4-addition of diethylzinc to cyclohexenone. Excellent reaction rates (TOF>1200 hsu
Copper-catalysed asymmetric conjugate addition of organometallic reagents to linear enones using thiourethane ligands
Bennett, Simon M.W.,Brown, Stephen M.,Muxworthy, James P.,Woodward, Simon
, p. 1767 - 1770 (1999)
In the presence of chiral thiourethane ligands [Cu(MeCN)4]BF4 forms active catalysts for the conjugate addition of MeMgBr, ZnEt2 and AlR3 (R = Me, Et) to non-3-en-2-one, hept-3-en-2-one, and 5-methylhex-3-en-2-one. Enantioselectivities of up to 51% are realised for these difficult substrates; for cyclohex-2-enone an e.e. of 42% is attained.
Diastereoselective synthesis of pyridyl substituted thiazolidin-4-ones. New ligands for the Cu(I) catalyzed asymmetric conjugate addition of diethylzinc to enones
De Vries, Andre H. M.,Hof, Robert P.,Staal, Danny,Kellogg, Richard M.,Feringa, Ben L.
, p. 1539 - 1543 (1997)
Several novel thiazolidin-cones have been synthesized from chiral nonracemic α-mercapto acids by a three component reaction in high yields and with diastereomeric excesses up to 91%. After recrystallization, the thiazolidinones were obtained diastereomeri
Significant asymmetric amplification in enantioselective Cu/DiPPAM-catalyzed 1,6- and 1,4-conjugate additions of diethylzinc to (Di)enones
Magrez, Magaly,Wencel-Delord, Joanna,Alexakis, Alexandre,Crevisy, Christophe,Mauduit, Marc
, p. 3576 - 3579 (2012)
An unprecedented and strong positive nonlinear effect (NLE) was observed in Cu/DiPPAM-catalyzed asymmetric 1,6-conjugate addition of Et2Zn on (E)-3-(prop-1-en-1-yl)cyclohex-2-enone (71% ee reached with a 40% ee ligand). Moreover, similar behaviors were observed in Cu/DiPPAM-catalyzed 1,4-asymmetric conjugate additions of Et2Zn on both cyclohexenone and (E)-3-non-3-en-2-one (83% and 70% ee, respectively, reached with a 40% ee ligand).
Sugar-phosphite-oxazoline and phosphite-phosphoroamidite ligand libraries for Cu-catalyzed asymmetric 1,4-addition reactions
Mata, Yvette,Dieguez, Montserrat,Pamies, Oscar,Biswas, Kallolmay,Woodward, Simon
, p. 1613 - 1617 (2007)
Sugar-phosphite-oxazoline L1-L5a-g and phosphite-phosphoroamidite L6a-c ligand libraries were tested in the asymmetric Cu-catalyzed 1,4-conjugate addition reactions of cyclic and acyclic enones. Systematically varying the electronic and steric properties
Diastereoselective alkylation of (arene)tricarbonylchromium and ferrocene complexes using a chiral, C2symmetrical 1,2-diamine as auxiliary
Alexakis, Alexandre,Tomassini, Axel,Andrey, Olivier,Bernardinelli, Gerald
, p. 1332 - 1339 (2005)
The aminal of (benzaldehyde)tricarbonylchromium and enantiopure bipyrrolidine undergoes diastereoselective ortho-metallation with butyllithium. Quenching with various electrophiles, followed by hydrolysis of the aminal, affords ortho-substituted (benzalde
Copper-catalyzed enantioselective conjugate addition of diethylzinc using axially chiral aminoethyloxy-phosphine ligands
Morimoto, Toshiaki,Obara, Nobuhiro,Yoshida, Iku,Tanaka, Kiyoshi,Kan, Toshiyuki
, p. 3093 - 3095 (2007)
New axially chiral P,O,N-type ligands bearing both a diphenylphosphino group and 2-(dialkylamino)ethyloxy (or 2-pyridylmethyloxy) groups were designed and prepared along with P,O,O-type ligands by employing an easily available chiral component, (R)-2-hydroxy-2′-diphenylphosphinyl-1,1′-binaphthyl. Among the ligands the simplest P,O,N-type one bearing a 2-(dimethylamino)ethyloxy group was found to be the most efficient in copper-catalyzed enantioselective conjugate addition of diethylzinc to a cyclic enone, 2-cyclohexen-1-one, providing high enantioselectivity up to 99% ee.
Asymmetric lithium(I) and copper(II) alkoxy-N-heterocyclic carbene complexes; crystallographic characterisation and Lewis acid catalysis
Arnold, Polly L.,Rodden, Mark,Davis, Kate M.,Scarisbrick, Andrew C.,Blake, Alexander J.,Wilson, Claire
, p. 1612 - 1613 (2004)
A one-pot synthesis of a wide range of bidentate, alkoxide-N-heterocyclic carbene ligands provides new lithium alkoxy-carbenes and a range of covalently bound organometallic Cu(II) carbene complexes, which are catalytically active, in some cases enantiose
Deciphering Reactivity and Selectivity Patterns in Aliphatic C-H Bond Oxygenation of Cyclopentane and Cyclohexane Derivatives
Martin, Teo,Galeotti, Marco,Salamone, Michela,Liu, Fengjiao,Yu, Yanmin,Duan, Meng,Houk,Bietti, Massimo
supporting information, p. 9925 - 9937 (2021/06/30)
A kinetic, product, and computational study on the reactions of the cumyloxyl radical with monosubstituted cyclopentanes and cyclohexanes has been carried out. HAT rates, site-selectivities for C-H bond oxidation, and DFT computations provide quantitative information and theoretical models to explain the observed patterns. Cyclopentanes functionalize predominantly at C-1, and tertiary C-H bond activation barriers decrease on going from methyl- and tert-butylcyclopentane to phenylcyclopentane, in line with the computed C-H BDEs. With cyclohexanes, the relative importance of HAT from C-1 decreases on going from methyl- and phenylcyclohexane to ethyl-, isopropyl-, and tert-butylcyclohexane. Deactivation is also observed at C-2 with site-selectivity that progressively shifts to C-3 and C-4 with increasing substituent steric bulk. The site-selectivities observed in the corresponding oxidations promoted by ethyl(trifluoromethyl)dioxirane support this mechanistic picture. Comparison of these results with those obtained previously for C-H bond azidation and functionalizations promoted by the PINO radical of phenyl and tert-butylcyclohexane, together with new calculations, provides a mechanistic framework for understanding C-H bond functionalization of cycloalkanes. The nature of the HAT reagent, C-H bond strengths, and torsional effects are important determinants of site-selectivity, with the latter effects that play a major role in the reactions of oxygen-centered HAT reagents with monosubstituted cyclohexanes.
Counterion Enhanced Organocatalysis: A Novel Approach for the Asymmetric Transfer Hydrogenation of Enones
Scharinger, Fabian,Márk Pálv?lgyi, ádám,Zeindlhofer, Veronika,Schnürch, Michael,Schr?der, Christian,Bica-Schr?der, Katharina
, p. 3776 - 3782 (2020/06/22)
We present a novel strategy for organocatalytic transfer hydrogenations relying on an ion-paired catalyst of natural l-amino acids as main source of chirality in combination with racemic, atropisomeric phosphoric acids as counteranion. The combination of a chiral cation with a structurally flexible anion resulted in a novel chiral framework for asymmetric transfer hydrogenations with enhanced selectivity through synergistic effects. The optimized catalytic system, in combination with a Hantzsch ester as hydrogen source for biomimetic transfer hydrogenation, enabled high enantioselectivity and excellent yields for a series of α,β-unsaturated cyclohexenones under mild conditions. Moreover, owing to the use of readily available and chiral pool-derived building blocks, it could be prepared in a straightforward and significantly cheaper way compared to the current state of the art.
CuI-Catalysed Enantioselective Alkyl 1,4-Additions to (E)-Nitroalkenes and Cyclic Enones with Phosphino-Oxazoline Ligands
Shin, Minkyeong,Gu, Minji,Lim, Sung Soo,Kim, Min-Jae,Lee, JuHyung,Jin, HyeongGyu,Jang, Yun Hee,Jung, Byunghyuck
, p. 3122 - 3130 (2018/07/06)
Catalytic enantioselective conjugate additions of simple alkyl groups to nitroalkenes or cyclic enones that result in the formation of tertiary C–C bonds are described. For these stereoselective addition reactions, new chiral phosphino-oxazoline ligands w
