Preparation of 4,6-Disubstituted α-Pyrones by Oxidative N-Heterocyclic Carbene Catalysis
作者:Armido Studer、Srikrishna Bera
DOI:10.1055/s-0036-1588336
日期:——
driving force in carbene catalysis, on the occasion of his 70th birthday Abstract An efficient synthesis of 4,6-disubstituted α-pyrones employing redox activation of enals using N-heterocyclic carbene catalysis is reported. The strategy uses aroyl-substituted nitromethanes and enals as substrates and reactions proceed through an addition–elimination–lactonization sequence. On one hand the nitro group
Transfer Hydrogenation in Water: Enantioselective, Catalytic Reduction of α-Cyano and α-Nitro Substituted Acetophenones
作者:Omid Soltani、Martin A. Ariger、Henar Vázquez-Villa、Erick M. Carreira
DOI:10.1021/ol1008894
日期:2010.7.2
Catalytic reduction of α-substituted acetophenones under conditions involving asymmetric transfer hydrogenation in water is described. The reaction is conducted in water and open to air, and formic acid is used as reductant.
α-Nitro Ketone Synthesis Using <i>N</i>-Acylbenzotriazoles
作者:Alan R. Katritzky、Ashraf A. A. Abdel-Fattah、Anna V. Gromova、Rachel Witek、Peter J. Steel
DOI:10.1021/jo051231x
日期:2005.11.1
Readily available N-acylbenzotriazoles 2a−l (derived from a variety of aliphatic, (hetero)aromatic, and N-protected α-amino carboxylic acids) smoothly convert primary 3a−c and α-functionalized primary nitroalkanes 3d into the corresponding α-nitro ketones 5a−p in yields of 39−86% (average 63%).
New methods and reagents in organic synthesis. 9. C-Acylation of nitromethane with aromatic carboxylic acids using diethyl phosphorocyanidate (DEPC).
作者:YASUMASA HAMADA、KIYOKO ANDO、TAKAYUKI SHIOIRI
DOI:10.1248/cpb.29.259
日期:——
Aromatic α-nitroketones can be conveniently prepared from aromatic carboxylic acids and nitromethane by the action of diethyl phosphorocyanidate (DEPC) in the presence of triethylamine.
Iridium Diamine Catalyst for the Asymmetric Transfer Hydrogenation of Ketones
作者:Henar Vázquez-Villa、Stefan Reber、Martin A. Ariger、Erick M. Carreira
DOI:10.1002/anie.201102732
日期:2011.9.12
A simple and very efficient chiral aqua iridium(III) diamine complex leads to excellent enantioselectivities in the asymmetrictransferhydrogenation of various α‐cyano and α‐nitro ketones. The catalyst provides the ortho‐substituted aromatic alcohols with especially high ee values. The diamine ligands can be used directly as chiral ligands; conversion into the corresponding sulfamide is not necessary