Thanh Binh Nguyen

Selective autoxidation of benzylamines: application to the synthesis of some nitrogen heterocycles

A green and remarkably simple synthesis of nitrogen heterocycles from benzylamines and anilines o-substituted by a cyclizable group has been developed based on selective uncatalyzed autoxidation of benzylamines.

Elemental Sulfur Disproportionation in the Redox Condensation Reaction between o‐Halonitrobenzenes and Benzylamines

The disproportionation of elemental sulfur at moderate temperatures is investigated in the redox condensation involving o-halonitrobenzenes 1 and benzylamines 2. As a redox moderator, elemental sulfur plays the dual role of both electron donor and acceptor, generating its lowest and highest oxidation states: S(-2) (sulfide equivalent) in benzothiazole 3 and S(+6) (sulfate equivalent) in sulfamate 4, and filling the electron gap of the global redox condensation process. Along with this process, a cascade of reactions of reduction of the nitro group of 1, oxidation of the aminomethyl group of 2, metal-free aromatic halogen substitution, and condensation finally led to 2-arylbenzothiazoles 3.

Chiral Phosphoric Acid Catalyzed Enantioselective Transfer Hydrogenation of ortho-Hydroxybenzophenone NH Ketimines and Applications

Keywords: amines ; chirality ; enantioselectivity ; Hantzsch ester ; hydrogenation ; phosphoric acid ; Asymmetric Transfer Hydrogenation ; Alpha-Imino Esters ; Organocatalytic Transfer Hydrogenation ; Friedel-Crafts Reaction ; Bronsted Acid ; Arylboronic Acids ; Organometallic Reagents ; Reductive Amination ; Cetirizine Hydrochloride ; 3-Component Reaction Reference EPFL-ARTICLE-168571doi:10.1002/chem.201101694View record in Web of Science Record created on 2011-08-31, modified on 2017-05-12

Fe/S-catalyzed decarboxylative redox condensation of arylacetic acids with nitroarenes

Fe/S clusters generated in situ from simple iron salts and sulfur S8 were found to be highly efficient to catalyze the decarboxylative redox condensation of arylacetic acids with nitroarenes in the presence of N-methylpiperidine as a basic additive. A wide range of aza-heterocycles was obtained in an atom-, step-, and redox-economical manner with water and carbon dioxide as the only by-products.

Elemental sulfur as a polyvalent reagent in redox condensation with o-chloronitrobenzenes and benzaldehydes: three-component access to 2-arylbenzothiazoles

Sulfur was found to be a polyvalent reagent in the multicomponent redox condensation with o-chloronitrobenzenes and benzaldehydes. 2-Arylbenzothiazoles was obtained in moderate to good yields in a highly atom-economical pathway.

Formic acid as a sustainable and complementary reductant: an approach to fused benzimidazoles by molecular iodine-catalyzed reductive redox cyclization of o-nitro-t-anilines

Molecular iodine was found to be an excellent catalyst for reductive redox cyclization of o-nitro-t-anilines 1 into fused tricyclic or 1,2-disubtituted benzimidazoles 2. A range of functional groups such as halides (F, Cl, Br), methoxy, ester, trifluoromethyl, cyano, pyridine and even nitro groups were tolerated using formic acid as a clean, safe, user-friendly and complementary reductant. When iodine was used in a stoichiometric amount (50 mol%), the methodology allowed the direct synthesis of benzimidazole hydroiodides 2·HI in high yields by simple precipitation from the reaction mixture.

Sulfurative self-condensation of ketones and elemental sulfur: a three-component access to thiophenes catalyzed by aniline acid–base conjugate pairs

A sulfurative self-condensation method for constructing thiophenes 2 by a reaction between ketones 1 and elemental sulfur is reported. This reaction, which is catalyzed by anilines and their salts with strong acids, starts from readily available and inexpensive materials, and releases only water as a by-product.

Methyl ketone break-and-rebuild: a strategy for full α-heterofunctionalization of acetophenones

The Willgerodt reaction under iron-catalyzed aerobic conditions was found to be an excellent tool for full α-heterofunctionalization of acetophenones with sulfur and amines. Via this break-and rebuild strategy, a wide range of thioglyoxamides was synthesized in a four-component, highly atom-, step- and redox-economical manner with water as the only by-product.

PRACTICAL SYNTHESIS OF N-ARYL-o-HYDROXYARYL KETIMINES

Abstract Heating o-hydroxyacetophenones and anilines under solvent-free conditions afforded the corresponding aryl ketimines in good to excellent yields. GRAPHICAL ABSTRACT