Enantioselective control of the chirality of a tertiary a-carbon in the products of a Nazarov cyclization of enones is challenging because the reaction involves an enantioselective proton transfer process. We herein report the use of cooperative catalysis using Lewis acids and chiral Brønsted acids to control the stereochemistry of the tertiary a-carbon in the products of this reaction. Specifi...

a preliminary study on statistical modelling of a process for depolymerisation of cassava non-starch carbohydrate using halide salt assisted phosphoric and pyruvic acids were accomplished. the effects of three independent variables namely; acid concentration, potassium iodide salt and duration were studied using the central composite rotatable design on hydrolysis of the cassava non-starch carb...

Ergönül P.G., Nergiz C. (2010): Determination of organic acids in olive fruit by HPLC. Czech J. Food Sci., 28: 202–205. Organic acids (oxalic, citric, malic, and succinic) contents of Domat, Memecik and Uslu varieties of olives grown in Turkey were investigated using HPLC method. Organic acids were extracted from olives with water-methanol mixture solution 75:25 (v/v) and were analysed through ...

A preliminary study on statistical modelling of a process for depolymerisation of cassava non-starch carbohydrate using halide salt assisted phosphoric and pyruvic acids were accomplished. The effects of three independent variables namely; acid concentration, potassium iodide salt and duration were studied using the central composite rotatable design on hydrolysis of the cassava non-starch carb...

A highly enantioselective Biginelli reaction promoted by chiral spirocyclic SPINOL-phosphoric acids has been developed. Under the optimized conditions with 5 mol% catalyst loading, a wide range of optically active dihydropyrimidinethiones (DHPMs) were obtained in high yields (up to 98%) with good to excellent enantioselectivities (up to 99% ee). The synthetic utility of this method was demonstr...

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.

Mixed anhydrides of phosphorus sulfonic acids RR'P(O)OSOzR" 1 are of interest in the biological transfer of sulfates'. In the chemical synthesis of oligonucleotides, phosphoric sulfonic anhydrides 1 (R', R = nucleoside) are postulated as important and reactive intermediatesw-s-. Anhydrides 1 were also suggested as intermediates in biooxidation of thiolophosphates'. Structural analogues of anhyd...