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‐Dialkylhydrazones as Versatile Umpolung Reagents in Enantioselective Anion‐Binding Catalysis
作者:Melania Gómez‐Martínez、María Carmen Pérez‐Aguilar、Dariusz G. Piekarski、Constantin G. Daniliuc、Olga García Mancheño
DOI:10.1002/anie.202013380
日期:2021.3
ion‐pair complex was envisioned. The formation of such a network was further supported by both experimental and computationalstudies, which showed the crucial role of the anion as a template unit. The asymmetric Reissert‐type reaction of quinolines as a model test reaction chemoselectively delivered highly enantiomerically enriched hydrazones (up 95:5 e.r.) that could be further derivatized to value‐added
Studies on Stereoselective [2+2] Cycloadditions between N,N-Dialkylhydrazones and Ketenes
作者:Eloísa Martín-Zamora、Ana Ferrete、José M. Llera、Jesús M. Muñoz、Rafael R. Pappalardo、Rosario Fernández、José M. Lassaletta
DOI:10.1002/chem.200400452
日期:2004.12.3
chiral, non-racemic N,N-dialkylhydrazones 1 and functionalized ketenes constitute an efficient methodology for the stereoselective construction of the beta-lactam ring. The potential for fine tuning of the dialkylamino auxiliary structure, the availability of a high-yielding deprotection method for the release of the free azetidinones, and the high thermal and chemical stability of hydrazones as N-dialkylamino
A number of nitrile-containing chiral molecules were synthesized via asymmetric nucleophilic addition of formaldehyde N,N-dialkylhydrazone as the nitrile equivalent. Chiral N,N′-dioxide/metal salt complexes enabled the asymmetric addition reactions to both isatin-derived imines and α,β-unsaturated ketones, generating amino nitriles and 4-oxobutanenitrile derivatives in good yields with high enantioselectivities
Asymmetric Imino Aza-enamine Reaction Catalyzed by Axially Chiral Dicarboxylic Acid: Use of Arylaldehyde <i>N</i>,<i>N</i>-Dialkylhydrazones as Acyl Anion Equivalent
作者:Takuya Hashimoto、Maya Hirose、Keiji Maruoka
DOI:10.1021/ja802704j
日期:2008.6.18
Synthetic utility of arylaldehyde N,N-dialkylhydrazones as a practical acyl anion equivalent could be exploited for the first time in the asymmetric imino aza-enamine reaction catalyzed by axiallychiral carboxylic acid.
Formaldehyde dialkylhydrazones smoothly add to sugaraldehydes without any need of promoter or catalyst. α-Hydroxy dialkylhydrazones, which are obtained in good yields and high stereoselectivities, have been successfully transformed in cyanohydrins by treatment with magnesium monoperoxyphtalate (MMPP) and in O-protected α-hydroxy aldehydes by ozonolysis or HCl mediated hydrolysis. No racemization was