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.
Mechanistic-Insight-Driven Rate Enhancement of Asymmetric Copper-Catalyzed 1,4-Addition of Dialkylzinc Reagents to Enones
Lewis, William,Nouch, Ryan,Robinson, David,Willcox, Darren,Woodward, Simon
, (2020/03/13)
The combination of [Cu(MeCN)4]TFA·TFAH (TFA = O2CCF3) with Feringa's phosphoramidite ligand (LA) provides an exceptionally active (0.75 mol %) catalyst for asymmetric conjugate additions of ZnR2 (R = Et and Me at -40 to -80 °C) to enones. Kinetic and other studies of the addition of ZnEt2 to cyclohex-2-en-1-one indicate a transition state stoichiometry composition of (ZnEt2)3(enone)4Cu2(LA)3 that is generated by transmetalation from Et2Zn(enone)2. Catalyst genesis is significantly slower than turnover (which has limited previous attempts to attain useful kinetic data); in the initial stages, varying populations of catalytically inactive, off-cycle, species are present. These issues are overcome by a double-dose kinetic analysis protocol. A rest state of [LACu(Et)(μ-TFA)(μ-{(enone)(ZnEt)2(enolate)})CuLA2]+ (through the equivalence of enolate = enone + ZnEt2) is supported by DFT studies (ωB97X-D/SRSC). Rate-determining ZnEt2(enone)2 transmetalation drives the exceptionally high catalytic activity of this system.
Enantiopure sulfoximines-catalyzed 1, 4-additions to 2-en-ketone
Zhao, Hongwei,Han, Hui,Yang, Hengquan,wang, Li
, p. 210 - 213 (2018/06/26)
An efficient chiral catalyst procedure for the preparation of β-chiral ketone via the 1, 4-additions reaction of 2-en-ketone has been developed using enantiopure sulfoximines modified with functional groups as ligands. The carefully design and synthesized