A highly enantioselective hydrogenation of enamides catalyzed by a dual chiral-achiral acid system was developed. By employing a substoichiometric amount of a chiral phosphoric acid and acetic acid, catalyst loadings as low as 1 mol % of the chiral catalyst were sufficient to provide excellent yield and enantioselectivity of the reduction product.

BACKGROUND Solid acid catalyst was prepared from Kraft lignin by chemical activation with phosphoric acid, pyrolysis and sulfuric acid. This catalyst had high acid density as characterized by scanning electron microscope (SEM), energy-dispersive x-ray spectrometry (EDX) and Brunauer, Emmett, and Teller (BET) method analyses. It was further used to catalyze the esterification of oleic acid and o...

Direct sulfonation of methane with SO3 to methanesulfonic acid (MSA) is accomplished in sulfuric acid with almost 100% selectivity in the presence of a catalyst, namely, Ce and Rh salts and molecular oxygen as the catalyst regenerator. In the absence of O2, the catalyst remains effective but the selectivity to MSA decreases to 53% and byproducts, principally CH3OSO3H, are formed. The effects of...

d-tartaric acid is successfully used as a green and efficient catalyst for the synthesis of 3,4-dihydropyrimidin-2(1h)-ones under solvent-free conditions. the developed method has many advantages, including devoid of harmful catalyst and solvents, high yield and easily work-up.

A novel modified Fenton process using heterogeneous catalyst (swarf) was developed to catalyze the oxidation reaction of azo dye Acid Red 18. It was found that swarf could be used to replace iron salts as a catalyst for the Fenton reaction. The examined continuous Fenton process proved to be very efficient for decolorization of simulated wastewater containing 100 mg/dm3 Acid Red 18. Performance...

cellulose sulfuric acid as a bio-polymer based solid catalyst efficiently catalyzes the selectively oxidation of sulfides to sulfoxides and thiols to disulfides using hydrogen peroxide as a green oxidant with good yields at room temperature. the developed method offers a number of advantages such as high selectivity, mild reaction conditions, simple operation, cleaner reaction profiles, low cos...

ammonium monovanadate (nh4vo3) has been devoted as an efficient, commercially available, eco-friendly and reusable catalyst for the synthesis of bis(indolyl)methanes (bims), oxindole derivatives and also michael adducts of indoles at 50 °c under solvent-free conditions. the reusability of this solid acid catalyst in addition with its selectivity has also been examined.

for the first time lactic acid was applied as an efficient and green catalyst for the one-pot three-component synthesis of amidoalkyl naphthols via the condensation between arylaldehydes, 2-naphthol and amides or urea under thermal solvent-free conditions in good to excellent yields. we have demonestrated a mild and efficient eco-friendly tandem synthesis of amidoalkyl naphthols using lactic ac...

Kaolin-SO3H as a new solid acid is prepared via reaction of kaolin and chlorosulfonic acid. This natural based catalyst is very inexpensive and easy available. Imidazoles are an important class of heterocycles being the core fragment of different natural products and biological systems such as anti-allergic, anti-inflammatory, analgesic, antifungal, antimycotic, antibiotic, antiulcerative, anti...

a simple and mild one-pot three-component reaction for the preparation 1,4-dihydropyridines has been developed from various aldehyde substrates, 1,3-dicarbonyl compounds (dimedone) and ammonium acetate (hantzsch method) in the presence of a catalytic amount of phospho sulfonic acid (psa) as an efficient and heterogeneous solid acid in etoh at room temperature. preparation of psa is straightforw...