- Design of new axially chiral NADH mimics. Mechanistic investigation of the enantioselective hydride transfer
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This paper reports the design of a new axially chiral NADH model which relies on the configurational control around the C3-C=O chiral axis by means of a chiral relay installed on the cyclic structure. The conformational and configurational control of the
- Vasse, Jean-Luc,Dupas, Georges,Duflos, Jack,Quéguiner, Guy,Bourguignon, Jean,Levacher, Vincent
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- USEFUL CHIRAL LACTONES DERIVED FROM CIS-BICYCLOOCTAN-3,7-DIONE VIA ASYMMETRIC DEPROTONATION
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The monoketal derived from cis-bicyclooctane-3,7-dione was deprotonated using chiral lithium amide bases and the enolates were trapped as either enol acetates or trimethylsilyl enol ethers.Oxidative cleavage of the enol derivatives provided useful
- Leonard, John,Hewitt, Jacqueline D.,Ouali, Dehimi,Rahman, Shirley K.,Simpson, Stephen J.
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- Continuous Flow Chiral Amine Racemization Applied to Continuously Recirculating Dynamic Diastereomeric Crystallizations
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A new, dynamic diastereomeric crystallization method has been developed, in which the mother liquors are continuously separated, racemized over a fixed-bed catalyst, and recirculated to the crystallizer in a resolution-racemization-recycle (R3) process. S
- Kwan, Maria H. T.,Breen, Jessica,Bowden, Martin,Conway, Louis,Crossley, Ben,Jones, Martin F.,Munday, Rachel,Pokar, Nisha P. B.,Screen, Thomas,Blacker, A. John
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p. 2458 - 2473
(2021/02/06)
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- Enantioselective reduction of: N -alkyl ketimines with frustrated Lewis pair catalysis using chiral borenium ions
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Enantioselective reduction of ketimines was demonstrated using chiral N-heterocyclic carbene (NHC)-stabilised borenium ions in frustrated Lewis pair catalysis. High levels of enantioselectivity were achieved for substrates featuring secondary N-alkyl substituents. Comparative reactivity and mechanistic studies identify key determinants required to achieve useful enantioselectivity and represent a step forward in the further development of enantioselective FLP methodologies.
- Mercea, Dan M.,Howlett, Michael G.,Piascik, Adam D.,Scott, Daniel J.,Steven, Alan,Ashley, Andrew E.,Fuchter, Matthew J.
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supporting information
p. 7077 - 7080
(2019/06/20)
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- Diastereoselective desymmetrization of diarylphosphinous acid-borane amides under Birch reduction
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Treatment of diarylphosphinous acid-borane amides possessing chiral amido functionality with an alkali metal solution in liquid ammonia induced a preferential dearomatization of one aryl substituent at phosphorus leading to the formation of non-equimolar amounts of diastereomers. Diastereoselectivity of dearomatization depends strongly on the structure of a chiral auxiliary.
- Stankevi?, Marek
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p. 6082 - 6102
(2015/06/08)
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- Efficient, selective, and green: Catalyst tuning for highly enatioselective reactions of ethylene
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Fine tuning of the biaryl and amino moieties of Feringa's phosphoramidite ligands yields structurally simpler, yet more efficient and selective, ligands for asymmetric hydrovinylation of vinylarenes and acylic 1,3-dienes. The enantioselectivities and yields observed in the formation of the 3-arylbutenes are among the highest for all asymmetric catalytic processes reported to date for the synthesis of intermediates for the widely used antiinflammatory 2-arylpropionic acids including naproxen, ibuprofen, fenoprofen, and flurbiprofen.
- Smith, Craig R.,Rajanbabu
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supporting information; experimental part
p. 1657 - 1659
(2009/04/10)
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- Synthesis and dynamics of atropisomeric (S)-N-(α-phenylethyl)benzamides
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The synthesis of atropisomeric 2-substituted benzamides 2a-e, 3a-e, and 4a-e, and characterization by X-ray structure analysis of 2d, 2e, 3c, 3e, 4c, and 4e are reported. Dynamic 1H NMR spectroscopic studies of benzamides 2b-d, 3b-d, and 4b-d i
- Huelgas, Gabriela,Bernès, Sylvain,Sánchez, Mario,Quintero, Leticia,Juaristi, Eusebio,Anaya de Parrodi, Cecilia,Walsh, Patrick J.
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p. 12655 - 12664
(2008/03/17)
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- Preparation of axially chiral quinolinium salts related to NAD+ models: New investigations of these biomimetic models as 'chiral amide-transferring agents'
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The general purpose of this work is to investigate the potential of biomimetic NAD+ models as 'nucleophile-transferring agents' with the ultimate motivation to develop new synthetic tools. This first report focuses on the preparation of an axially chiral quinolinium salt 8. A preliminary investigation of these NAD+ analogues as 'chiral amide-transferring agents' is reported herein. The synthesis of the desired quinolinium salt 8 was first attempted via a Friedlaender approach. Given the poor reproducibility of this first synthetic route, a second strategy making use of an intramolecular nickel-catalyzed coupling was developed with success, furnishing the quinolinium salt 8 in 12% overall yield. The potential of the quinolinium salt 8 as a 'chiral amide-transferring agent' was then investigated. Regioselective 1,4-addition of benzylamine and piperidine produced, respectively, adducts 18a and 18b with high diastereoselectivity (de >95%). The resulting 'chiral masked-amide' 18b was reacted with various activated aryl esters affording the corresponding atropisomeric amide 20 with modest atropenantioselectivity (ee = 2-20%).
- Leleu, Stephane,Papamicael, Cyril,Marsais, Francis,Dupas, Georges,Levacher, Vincent
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p. 3919 - 3928
(2007/10/03)
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- Diastereoselective carbozincation of propargylic amines
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The carbometalation of propargylic amines derived from methylbenzylamine takes place with good 1,3-diastereoselection in the presence of Lewis acids.
- Rezaei, Hadi,Marek, Ilan,Normant, Jean F
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p. 2477 - 2483
(2007/10/03)
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- Enantioselective Deprotonation of Benzyl Phosphates by Homochiral Lithium Amide Bases - Configurational Stability of Benzyl Carbanions with a Dialkoxyphosphoryloxy Substituent and Their Rearrangement to Optically Active α-Hydroxy Phosphonates
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Benzyl dialkyl phosphates are deprotonated enantioselectively by homochiral lithium amides of isopropyl(1-phenylethyl)amine or bis(1-phenylethyl)amine.The short-lived benzylic carbanions formed are virtually configurationally stable relative to the rearrangement to optically active phenylhydroxymethylphosphonates.The enantiomeric excesses are up to 50percent.The pro-(S) hydrogen is removed by amides having (S) configuration.Homochiral diethyl (S)-phenylmethyl phosphate is deprotonated by both LDA and n-BuLi with a high primary kinetic isotope effect (kH/D ca. 50) and isomerizes to the corresponding α-hydroxy phosphonate with an enantiomeric excess of up to 85percent. - Keywords: Phosphate-phosphonate rearrangement / Carbanions, benzylic, configurational stability of / Phosphonates / Lithium amides, homochiral
- Hammerschmidt, Friedrich,Hanninger, Achim
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p. 823 - 830
(2007/10/02)
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- Use of N,N'-dimethylpropyleneurea (DMPU) as solvent in the efficient preparation of enantiomerically pure secondary amines
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The monoalkylation of (R)- and (S)-1-phenylethylamine proceeds readily with DMPU as the solvent. An efficient procedure was then developed for the high-yield preparation of the chiral secondary amines N-benzyl-, N-isopropyl-, N-(2-biphenylyl)methyl-, N-(diphenyl)methyl-, and N-(2,2-dimethyl)propyl-1-phenylethylamine, in enantiomerically pure form.
- Juaristi,Murer,Seebach
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p. 1243 - 1246
(2007/10/02)
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- Asymmetric Synthesis of Mellein Methyl Ether: Use of ortho-Toluate Carbanions Generated by Chiral Bases
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An ortho-toluate carbanion generated from (2) by the chiral lithium amide base (6), (7), or (11) undergoes an enantioselective aldol-type reaction with acetaldehyde to give mellein methyl ether (3), in up to 53 percent enantiomeric excess.
- Regan, Andrew C.,Staunton, James
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p. 764 - 765
(2007/10/02)
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