- Asymmetric synthesis of propargylamides via 3,3′-disubstituted binaphthol-modified alkynylboronates
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(Chemical Equation Presented) Alkynylboronates derived from 3,3′-disubstituted-2,2′-binaphthols react with various N-acylimines to give the expected chiral propargylamides with up to 99% ee. This new methodology was applied to the first enantioselective s
- Wu, T. Robert,Chong, J. Michael
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- Oxidative Mannich reaction of N-carbobenzyloxy amines with 1,3-dicarbonyl compounds
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(Chemical Equation Presented) Efficient carbon-carbon bond formation at the α-position of nitrogen was established by one-pot oxidative Mannich reaction of N-carbobenzyloxy (Cbz) amines with 1,3-dicarbonyl compounds using N-tert-butylbenzenesulfinimidoyl chloride as an oxidant.
- Matsuo, Jun-Ichi,Tanaki, Yumi,Ishibashi, Hiroyuki
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p. 4371 - 4374
(2007/10/03)
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- Enantioselective aza-Henry reactions assisted by ZnII and N-methylephedrine
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(Chemical Equation Presented) Hooray aza-Henry! A combination of zinc triflate, an amine base, and (-)-N-methylephedrine (NME), which can be easily recovered and reused, leads to high enantioselectivities in the aza-Henry reaction of N-Boc-protected aldimines and nitromethane (see scheme; Boc = tert-butyloxycarbonyl).
- Palomo, Claudio,Oiarbide, Mikel,Halder, Rajkumar,Laso, Antonio,Lopez, Rosa
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p. 117 - 120
(2007/10/03)
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- Direct enantio- and diastereoselective Mannich reactions of malonate and β-keto esters with N-Boc and N-Cbz aldimines catalysed by a bifunctional cinchonine derivative
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A highly enantioselective Mannich reaction between malonate esters and N-Boc and N-Cbz aldimines, catalysed by a bifunctional cinchonine derivative, has been developed; extension of this methodology to encompass the use of 2-substituted-1,3-dicarbonyl nuc
- Tillman, A. Louise,Ye, Jinxing,Dixon, Darren J.
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p. 1191 - 1193
(2008/02/03)
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- Scope and limitations in sulfur ylide mediated catalytic asymmetric aziridination of imines: Use of phenyldiazomethane, diazoesters and diazoacetamides
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Imine aziridination using diazo-compounds and catalytic quantities of metal salts and sulfides has been investigated. A range of imines derived from benzaldehyde bearing electron-withdrawing groups (N-Ts,N-SO2CH2CH2SiMesu
- Aggarwal,Ferrara,O'Brien,Thompson,Jones,Fieldhouse
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p. 1635 - 1643
(2007/10/03)
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- N-alkyloxycarbonyl-3-aryloxaziridines: Their preparation, structure, and utilization as electrophilic amination reagents
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This paper reports the synthesis of a series of N-protected oxaziridines (N-Moc, Boc, Z or Fmoc) and discusses their ability to deliver their N-alkoxycarbonyl fragment to amines, enolates, sulfur, and phosphorus nucleophiles (electrophilic amination). These oxaziridines are prepared by oxidation of the corresponding imines with oxone or anhydrous MCPBA lithium salt as the source of oxygen. They transfer their N-protected fragment to primary and secondary amines to give protected hydrazines in fair to excelent yield. The nitrogen transfer to free amino acids (in form of their R4N+ salts) is particularly fast, even at low temperature, providing L (or D) N-protected α-hydrazino acids. Enolates are C-aminated to give N-protected α-amino ketones, esters, or amides in modest yield, due to a side aldol reaction of the unreacted enolate with the released benzaldehyde. With tertiary amines (Et3N), sulfides (PhSMe), and phosphines (Ph3P), amination and oxidation proceed in a parallel way; the amount of amination product increases when the temperature is lowered (kinetic control). Some of the factors that can orient the oxaziridine reactivity towards amination or oxidation of nucleophiles are considered.
- Vidal, Joelle,Damestoy, Stephanie,Guy, Laure,Hannachi, Jean-Christophe,Aubry, Andre,Collet, Andre
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p. 1691 - 1709
(2007/10/03)
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