- 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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- cis-(±)-5-[2- (Dimethylamino)ethyl]-3-hydroxy-2-(4- methoxyphenyl )-2,3,4,5-tetrahydro-1,5-benzothiazepin-4-one
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The title compound, C20H24N2O3S, is a drug intermediate of diltiazem. The molecule is stabilized by covalent bonding and weak hydrogen bonding, and the crystal packing is stabilized by hydrogen bonding. The seven-membered ring is distorted showing a twist-boat conformation. The methoxyphenyl and hydroxy groups are cis oriented with respect to one another, with the phenyl ring in an axial position. Intermolecular hydrogen bonding produces dimers in the crystal.
- Kumaradhas,Nirmala,Sridhar
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p. 2595 - 2597
(2007/10/03)
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- Stereoselective addition of 2-aminothiophenol to α-alkoxycinnamic acid derivatives - Alternative synthesis of (±)-diltiazem
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A stereocontrolled synthesis of (±)-diltiazem by applying nucleophilic addition of 2-aminothiophenol to α-alkoxycinnamic acid derivatives is described.
- Miyata, Okiko,Shinada, Tetsuro,Naito, Takeaki,Ninomiya, Ichiya,Date, Tadamasa,Okamura, Kimio
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p. 8119 - 8128
(2007/10/02)
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- Synthesis of the optically active trans-isomers of diltiazem and their cardiovascular effects and Ca-antagonistic activity
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Optically active trans-isomers of diltiazem were synthesized and their cardiovascular effects were evaluated in anesthetized dogs and in isolated guinea pig hearts. Both (+)-2 (2R,3S) and (-)-2 (2S,3R) were much less active than diltiazem (1, 2S,3S) with
- Tanaka,Inoue,Date,Okamura,Aoe,Takeda,Kugita,Murata,Yamaguchi,Kikkawa,Nakajima,Nagao
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p. 1476 - 1480
(2007/10/02)
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