摘要:
Acetylsalicylic acid esters of carnitine are distinguished relative to acetylsalicylic acid. The esters can be produced by acetylation of suitable salicylic acid esters of carnitine.
摘要:
Process for the production of an optically active 3-aminocarboxylic acid ester from a .beta.-keto acid ester. The .beta.-keto acid ester is converted with a chiral amine into the corresponding enamine. The enamine is converted by hydrogenation in the presence of a platinum catalyst into the corresponding N-substituted amino acid esters. Such ester mix is converted by means of HCl gas into the hydrochlorides. The latter are neutralized. Then by liberation and isolation from the neutralized products by hydrogenolysis in the presence of a palladium catalyst, the desired optically-active 3-aminocarboxylic acid ester is obtained.
摘要:
Starting from 5-alkylidene or 5-benzylidenetetramic acid, optically-active 4-amino-3-hydroxy-carboxylic acids are produced in the (rel-3R,4R) configuration, especially statine. The synthesis process includes the O-acylation of the tetramic acid to the corresponding 4-acyloxy-3-pyrrolin-2-one, a stereoselective hydrogenation to (rel-4R,5R)-4-acyloxy-5-alkyl or 5-benzylpyrrolidin-2-one and an enantioselective enzymatic hydrolysis of the (4R,5R)-enantiomer to the corresponding 4-hydroxypyrrolidin-2-one. The nonhydrolyzed enantiomer is separated and converted into the target compound with (3S,4S) configuration by hydrolytic cleavage of the lactam ring and the ester function and optionally introduction of an amino protective group. Analogously the (3R,4R)-enantiomer can be obtained from the 4-hydroxypyrrolidin-2-one from the enzymatic hydrolysis. The 4-amino-3-hydroxycarboxylic acids producible according to the invention are the structural elements of enzyme inhibitors.
摘要:
Process for the production of 4-alkoxy-2(5H) thiophenones, which are suitable as intermediate products, i.e., for the production of highly pure thiotetronic acid.
摘要:
4-Benzyloxy-3-pyrrolin-2-on-1-yl acetamide is an advantageous intermediate product for the production of pharmaceutically effective 4-hydroxypyrrolidin-2-1-yl acetamide. Processes for the production of the intermediate product as well as the active substance are described.
摘要:
Process for the production of imidazole derivatives of the formula: ##STR1## wherein R.sub.1 is an (R)- or (S)-1-phenylalkyl group, an (R)- or (S)-1-alkoxycarbonyl-1-phenylmethyl group or an (R)- or (S)-1-aryloxycarbonyl-1-phenylmethyl group, R.sub.2 is hydrogen, a substituted or unsubstituted alkanoyl group, an unsubstituted or a substituted benzoyl group, a substituted or an unsubstituted benzyl group, an alkoxycarbonyl group, and aryloxycarbonyl group, an alkoxyalkyl group, a pyranyl group, a substituted or unsubstituted benzenesulfonyl group, an alkylsulfonyl group, a diarylphosphinyl group, a dialkoxyphosphinyl group or a trialkylsilyl group, and A is a sulfur or oxygen atom. A tetronic acid of the formula: ##STR2## wherein A has the above-mentioned meaning, is reacted with a diazonium salt, converting the resultant arylazotetronic acid or the tautomeric arylhydrazone in a further step with a chiral amine into an arylazoamino compound, reducing the arylazoamino compound, converting the resultant diamine, with phosgene or a phosgene-equivalent reagent, into the corresponding imidazole and optionally introducing a protective group by reaction with a substituted or unsubstituted aliphatic or aromatic acid chloride, an aliphatic or aromatic carboxylic acid anhydride, a haloformic acid alkyl ester, a 1-alkoxyalkyl halide, an enol ether, an aromatic or aliphatic sulfonic acid halide, a diarylphosphinic acid halide, a phosphoric acid dialkyl ester halide, a trialkyl silyl halide or a trialkyl silyl acetamide. These imidazole derivatives are suitable as intermediate products for the production of (+) biotin.
摘要:
4-Benzyloxy-3-pyrrolin-2-on-1-yl acetamide is an advantageous intermediate product for the production of pharmaceutically effective 4-hydroxypyrrolidin-2-1-yl acetamide. Processes for the production of the intermediate product as well as the active substance are described.
摘要:
The enantiomers of 2,2-dimethylcyclopropanecarboxylic acid are separated by esterification with the hydroxy group of optically active mandelic acid methyl ester, crystallization of the diastereomeric esters and subsequent hydrolysis of the diastereomeric esters.
摘要:
The enantiomers of 2,2-dimethylcyclopropanecarboxylic acid are separated by salt formation with optically active 1-(3-methoxyphenyl)-ethylamine, fractional crystallization of the diastereomeric salts and subsequent decomposition of the salts with a strong acid.
摘要:
A process for the production or R,S-2,2-dimethylcyclopropanecarboxylic acid starting from isobutylene oxide and a phosphonoacetic acid trialkyl ester. In this way, first the R,S-2,2-dimethylcyclopropanecarboxylic acid-C.sub.1 -C.sub.4 alkyl ester is formed, which then is hydrolyzed to the corresponding acid. R,S-2,2-Dimethylcyclopropanecarboxylic acid is an important intermediate product for the production of S-(+)-2,2-dimethylcyclopropanecarboxamide.