Biodegradable Chitosan-Derived Thioureas as Recoverable Supported Organocatalysts - Application to the Stereoselective Aza-Henry Reaction
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چکیده
منابع مشابه
Vinylogy in nitronates: utilization of α-aryl conjugated nitroolefins as a nucleophile for a highly stereoselective aza-Henry reaction.
The vinylogous reactivity of α,β-disubstituted nitroolefins was uncovered through the facile generation of the corresponding α-substituted vinylogous nitronates and their use in the development of a highly diastereo- and enantioselective aza-Henry reaction with N-Boc aldimines under the catalysis of chiral ammonium betaines. The novel vinylogous nitronates undergo stereoselective bond formation...
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The catalytic activity of different supported bifunctional thioureas on sulfonylpolystyrene resins has been studied in the nitro-Michael addition of different nucleophiles to trans-β-nitrostyrene derivatives. The activity of the catalysts depends on the length of the tether linking the chiral thiourea to the polymer. The best results were obtained with the thiourea derived from (L)-valine and 1...
متن کاملWater-compatible hydrogen-bond activation: a scalable and organocatalytic model for the stereoselective multicomponent aza-Henry reaction.
The water paradigm has changed in organic chemistry. Multiple organic reactions have been implemented in the form of watercompatible processes with a net gain in efficiency and instrumental simplicity. Most of these reactions are currently performed either as homogeneous solutions or easily-stirred aqueous suspensions. Homogeneity requires either the use of water soluble reactants or the aid of...
متن کاملCatalytic enantioselective aza-Henry reaction with broad substrate scope.
In situ generated azomethines from readily available precursors react with nitromethane in the presence of 120 mol % of CsOH.H2O and 12 mol % of quinine- and cinchonidine-derived quaternary ammonium chlorides to provide the corresponding aza-Henry adducts in good yields and very high selectivities. It represents the first general enantioselective aza-Henry method for azomethines derived from en...
متن کاملHighly enantioselective aza-Henry reaction with isatin N-Boc ketimines.
A highly enantioselective aza-Henry reaction with isatin N-Boc ketimines using a Cu(II)-BOX complex as a catalyst is described. The reaction, which does not require protection of the N1 atom, provides the corresponding nitroamines bearing a quaternary stereocentre with high yields and enantiomeric excesses (up to 99.9%).
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ژورنال
عنوان ژورنال: European Journal of Organic Chemistry
سال: 2017
ISSN: 1434-193X
DOI: 10.1002/ejoc.201700582