- Preparation and purification method of diltiazem chiral isomer impurity
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The invention provides a method for preparing and purifying a diltiazem chiral isomer. The method comprises the steps of taking p-methoxybenzaldehyde as a starting raw material, carrying out Darzens condensation, a reaction with o-aminobenzenethiol and a cyclization reaction to prepare an intermediate, carrying out chiral column separation on the intermediate, then carrying out an alkylation and acetylation reaction separately to obtain a diltiazem chiral isomer impurity I. The method is simple to operate and short in period, and the purity of the obtained diltiazem chiral isomer impurity is high, so that a reference substance is provided for quality research and drug synthesis process research of diltiazem drugs, and the method has important significance in control and checking of the chiral purity in the pharmaceutical research of diltiazem.
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Paragraph 0017; 0019
(2019/11/20)
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- PROCESS FOR THE RECYCLE OF A WASTE PRODUCT OF DILTIAZEM SYNTHESIS
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A process which allows the re-use of compounds of formula in diltiazem synthesis through a process of conversion to a mixture of enantiomers III-(2R,3R) and III-(2S,3S) is described.
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- Process for the recycle of a waste product of diltiazem synthesis
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A process which allows the re-use of compounds of formula in diltiazem synthesis through a process of conversion to a mixture of enantiomers III-(2R,3R) and III-(2S,3S) is described.
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- Enantioselectivity of Pseudomonas cepacia lipase for the acetylation of 2-hydroxy carboxylic acid esters+
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Structurally different ethyl or methyl 2-hydroxy carboxylates were resolved by Pseudomonas cepacia lipase-catalysed acetylations with vinyl acetate in diethylether. One type of the alcoholic substrates (2-hydroxy-2-arylacetates and 2-hydroxy-3-arylpropinates) contained a HO-group at the stereocentre. These compounds were resolved with high enantioselectivity (ee 91 → 99) at ca. 50% conversion. The other alcoholic substrates ((threo-2-hydroxy-3-methylbutyrate and threo- or erythro-2-hydroxy-3-aryl-3-arylthio(or aryloxy)propionates) with two stereocentres generally resulted in enantiopure products and the reactions stopped at 50 % conversion.
- Sundholm, Oskari,Kanerva, Liisa T.
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p. 625 - 640
(2007/10/03)
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- Optical resolution of a 1,5-benzothiazepine derivative, a synthetic intermediate of diltiazem, by preferential crystallization and diastereomeric salt formation
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Practical preparation methods of an optically active intermediate of diltiazem, (+)-(2S,3S)-5-[2-(dimethylamino)ethyl]-2,3-dihydro-3-hydroxy-2- (4-methoxyphenyl)-1,5-benzothiazepin-4(5H)-one [(+)-7], have been developed by the use of physicochemical and chemical resolutions. 1) The salt of (+)-7 with 3-amino-4-hydroxy-benzenesulfonic acid (AHS), was found to exist as a conglomerate and could be reproducibly resolved into (+)-7·AHS and (-)- 7·AHS of 94-98% ee by a preferential crystallization procedure. 2) (+)- (1R)-3-Bromocamphor-9-sulfonic acid [(+)-BCS] was found to be an efficient resolving agent for (±)-7 and the diastereomeric resolution provided (+)- 7·(+)-BCS·2H2O salt in >43% yield and >97% ee by fractional crystallization. It is presumed that the crystal water of (+)-7·(+)- BCS·2H2O plays an important role in the selective crystallization during this efficient resolution.
- Yamada, Shin-Ichi,Yoshioka, Ryuzo,Shibatani, Takeji
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p. 1922 - 1927
(2007/10/03)
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- A microwave synthesis of the cis and trans isomers of 3-hydroxy-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one : The influence of solvent and power output on the diastereoselectivity
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A diastereoselective one-pot synthesis and the trans- and cis-3-hydroxy-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H) -one nucleus, a key intermediate in the preparation of the calcium channel blocker Diltiazem, is carried out under microwave irradiation in an open vessel. Control of the diastereoselectivity is achieved by varying the reaction time and power output as well as the nature of the solvent.
- Vega, Juan A.,Cueto, Senida,Ramos, Andres,Vaquero, Juan J.,Garcia-Navio, Jose L.,Alvarez-Builla, Julio,Ezquerra, Jesus
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p. 6413 - 6416
(2007/10/03)
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- Resolution process of intermediates useful for the preparation of diltiazem
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A process of spontaneous resolution of compounds of formula STR1 wherein R has the meanings reported in the description, is described. The compounds of formula III are intermediates useful for the preparation of Diltiazem.
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- Reaction of 3-Phenylglycidic Esters. III. Reaction of cis-3-Arylglycidic Esters with Various Thiophenols
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The reaction of the cis-3-arylglycidic esters 2 and 10 with thiophenols (3) has been investigated.The reactivity and stereoselectivity of the oxirane ring-opening of these cis-glycidic esters were lower than those of the trans-analogues (1 and 9).These tendencies were more apparent in the 4-MeO derivative (2).On the other hand, the tin-catalyzed reaction of 2 with 3a was highly stereospecific and afforded the cis-opening products (5a).Keywords - cis-3-arylglycidic ester; thiophenol; oxirane ring-opening; tin catalyst; stereoselectivity
- Hashiyama, Tomiki,Inoue, Hirozumi,Konda, Mikihiko,Takeda, Mikio
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p. 1256 - 1259
(2007/10/02)
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- Reaction of 3-Phenylglycidic Esters. Part 2. Stereo- and Regio-selectivity in the Oxirane Ring Opening of Methyl trans-3-(4-Methoxyphenyl)glycidate with Various Thiophenols and the Effects of Solvent and Temperature
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The effects of the solvent and temperature on the reaction of the trans-glycidate (1) with various substituted thiophenols (2) in the presence or absence of a catalyst have been investigated.The temperature had a surprisingly large effect on the stereochemistry of the oxirane ring-opening of (1).At room temperature, the erythro-isomer (4) (trans-opening product) was obtained as a major product in the absence of catalyst, while the cis-opening product (3) (threo-isomer) was produced predominantly at higher temperature.On the other hand, in a dipolar aprotic solvent, the regioisomer (5) was formed, the yield increasing with the electron-donating ability of the substituents on (2).The formation of compound (5) may involve single-electron transfer as a key step.
- Hashiyama, Tomiki,Inoue, Hirozumi,Takeda, Mikio,Aoe, Keiichi,Kotera, Keishi
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p. 421 - 428
(2007/10/02)
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