- HEXAHYDROPYRAZINOBENZ- OR -PYRIDO-OXAZEPINES CARRYING AN OXYGEN-CONTAINING SUBSTITUENT AND USE THEREOF IN THE TREATMENT OF 5-HT2C-DEPENDENT DISORDERS
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The present invention relates to compound of formula (I) (I) wherein the variables are as defined in the claims and the description. The invention further relates to a pharmaceutical composition containing such compounds, to their use as modulators, espec
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Page/Page column 72
(2017/06/27)
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- Novel method for synthesizing methyl aspartate
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The invention discloses a novel method for synthesizing methyl aspartate and belongs to the field of production of amino acids. The finished product namely methyl aspartate is prepared from aspartic acid powder, 30% sulfuric acid, pure water, a solid acid, a methanol solution and an alkali, which serve as raw materials, through preparing of aspartate sulfate, and esterifying of the aspartate sulfate. The method has the advantages that the process is simple, the source of the raw materials is wide, the operation is simple and convenient, the production cost is low, and the like, and the methyl aspartate finished product with high purity can be obtained. The novel method has the major advantages that the reaction condition is room temperature, so that the control is easy, and the energy consumption is low; through controlling the pH value, the production of byproducts such as dimethyl ester can be controlled, and the quality of the product is improved to some extent; and the yield can be increased by 40% or more.
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Paragraph 0021-0022
(2017/06/20)
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- Effect of the Side Chain on the Racemization of Amino Acids in Aqueous Solution
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The rate of racemization of 13 amino acids possessing hydroxy, carboxy, alkoxy, carboalkoxy, alkyl, aryl, and thioether side chains were compared.Reaction conditions were identical for all amino acids studied.Gas chromatography was used to determine the percent of D isomer present.Hydroxy amino acids racemized most rapidly, but conversion to an ether function reduced the rate considerably.The increased racemization rate of methionine (R = CH2CH2SCH3) over Ala (R = CH3) has been attributed to orbital overlap from the sulfur.Asp racemized faster than Glu, α-aminoadipic acid, and pyroglutamic acid. β- and γ-monomethyl esters of aspartic and glutamic acids, respectively, racemized only slightly faster than the corresponding free acids.The slight increase in rate appears attributable to a solvent change brought on by ester hydrolysis.Under the reaction conditions, pH 8 and 140 deg C, hydrolysis of the esters competed favorably with racemization at the methine carbon.The relatively lower racemization rate observed in the case of Glu compared with Asp resulted from the slow formation of pyroglutamic acid.Pyroglutamic acid racemized at a considerably slower rate than acidic amino acids.The differences in the racemization rates with changes in the R group are discussed in terms of several factors, including intramolecular reactions, direct field effects, orbital overlap, and solvation effects, as well as inductive, resonance, and steric factors.
- Smith, Grant Gill,Reddy, G. Vanita
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p. 4529 - 4535
(2007/10/02)
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- ENANTIOSPECIFIC SYNTHESIS OF A CHIRAL CARBAPENEM PRECURSOR FROM (R)-ASPARTIC ACID
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A short enantiospecific preparation of a key intermediate to carbapenem antibiotics with (R)-aspartic acid as chiral educt is described.
- Pellicciari, Roberto,Natalini, Benedetto,Ursini, Antonella
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p. 607 - 608
(2007/10/02)
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