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Methyl O (methyl + o)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

Regioselective C-6 Hydrolysis of Methyl O -Benzoyl-pyranosides Catalysed by Candida Rugosa Lipase

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 10 2009
Aslan Esmurziev
Abstract Hydrolysis of six methyl O -benzoyl-pyranosides has been investigated using Candida rugosa lipase in dioxane/buffer mixtures. The lipase catalysed the hydrolysis of all substrates in a regiospecific manner at C-6. The rate of reaction was dependent on pyranoside structure, reaction temperature and scale, dioxane concentration and agitation speed. Starting from their C-6 O -benzoyl precursors, the methyl 2,3,4-tri- O -benzoyl-pyranosides of ,- D -galactose, ,- D -galactose, ,- D -glucose, and methyl 2,3-di- O -benzoyl-,- D -galactopyranoside could be isolated in 85,96,% yield. In hydrolysis of methyl 2,3,4,6-tetra- O -benzoyl-,- D -glucopyranoside and methyl 2,3,4,6-tetra- O -benzoyl-,- D -galactopyranoside substrate inhibition were observed, which in part could be overcome by increasing the reaction volume. Methyl 2,3,4,6-tetra- O -benzoyl-,- D -glucopyranoside and methyl 2,3,4,6-tetra- O -benzoyl-,- D -mannopyranoside were poor substrates for Candida rugosa lipase and low degree of conversion towards products were obtained under all conditions. No acyl migration was detected in any of the products.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Hydrogen-bonding patterns in three substituted N -benzyl- N -(3- tert -butyl-1-phenyl-1H -pyrazol-5-yl)acetamides

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010
Gerson López
The molecules of N -(3- tert -butyl-1-phenyl-1H -pyrazol-5-yl)-2-chloro- N -(4-methoxybenzyl)acetamide, C23H26ClN3O2, are linked into a chain of edge-fused centrosymmetric rings by a combination of one C,H...O hydrogen bond and one C,H...,(arene) hydrogen bond. In N -(3- tert -butyl-1-phenyl-1H -pyrazol-5-yl)-2-chloro- N -(4-chlorobenzyl)acetamide, C22H23Cl2N3O, a combination of one C,H...O hydrogen bond and two C,H...,(arene) hydrogen bonds, which utilize different aryl rings as the acceptors, link the molecules into sheets. The molecules of S -[N -(3- tert -butyl-1-phenyl-1H -pyrazol-5-yl)- N -(4-methylbenzyl)carbamoyl]methyl O -ethyl carbonodithioate, C26H31N3O2S2, are also linked into sheets, now by a combination of two C,H...O hydrogen bonds, both of which utilize the amide O atom as the acceptor, and two C,H...,(arene) hydrogen bonds, which utilize different aryl groups as the acceptors. [source]

Highly Efficient Chemoenzymatic Synthesis of Methyl (R)- o -Chloromandelate, a Key Intermediate for Clopidogrel, via Asymmetric Reduction with Recombinant Escherichia coli

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 13 2008
Tadashi Ema
Abstract Methyl (R)- o -chloromandelate [(R)- 1], which is an intermediate for a platelet aggregation inhibitor named clopidogrel, was obtained in >99% ee by the asymmetric reduction of methyl o -chlorobenzoylformate (2) with recombinant Escherichia coli overproducing a versatile carbonyl reductase. A remarkable temperature effect on productivity was observed in the whole-cell reduction of 2, and the optimum productivity as high as 178,g/L was attained at 20,°C on a 2-g scale (1.0,M). The optimized reaction could be scaled up easily to transform 20,g of 2 in 100,mL of buffer. Three synthetic methods for 2 are compared. [source]