96994-58-0Relevant academic research and scientific papers
Optical resolution of a 1,5-benzothiazepine derivative, a synthetic intermediate of diltiazem, by preferential crystallization and diastereomeric salt formation
Yamada, Shin-Ichi,Yoshioka, Ryuzo,Shibatani, Takeji
, p. 1922 - 1927 (1997)
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.
Enantioselectivity of Pseudomonas cepacia lipase for the acetylation of 2-hydroxy carboxylic acid esters+
Sundholm, Oskari,Kanerva, Liisa T.
, p. 625 - 640 (2007/10/03)
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.
Reaction of 3-Phenylglycidic Esters. III. Reaction of cis-3-Arylglycidic Esters with Various Thiophenols
Hashiyama, Tomiki,Inoue, Hirozumi,Konda, Mikihiko,Takeda, Mikio
, p. 1256 - 1259 (2007/10/02)
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
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
Hashiyama, Tomiki,Inoue, Hirozumi,Takeda, Mikio,Aoe, Keiichi,Kotera, Keishi
, p. 421 - 428 (2007/10/02)
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.
