- Sulfuryl Chloride Promoted gem -Dichlorination-Dehydrochlorination in Alkyl Benzothiazinylacetates: Synthesis of the Skeleton of Trichochrome Pigments
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Chemo- and stereoselective total synthesis of the basic trichochrome skeleton is described starting from o-aminothiophenol and maleic anhydride in very good overall yield. The process involves the synthesis of the corresponding 1,4-benzothiazin-2-ylacetates followed by their sulfuryl chloride induced dihalogenation-dehydrohalogenation and a second condensation with o-aminothiophenol as key steps.
- Jangir, Ravi,Gadre, Smita R.,Argade, Narshinha P.
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p. 2631 - 2634
(2015/09/01)
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- Novel and potent aldose reductase inhibitors: 4-Benzyl- and 4- (benzothiazol-2-ylmethyl)-3,4-dihydro-3-oxo-2H-1,4-benzothiazine-2-acetic acid derivatives
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A number of 1,4-benzothiazine-2-acetic acid derivatives (1, 2 and 3) and their bioisosteres (15b, 16, 18 and 20b) were synthesized and evaluated in vitro for the ability to inhibit aldose reductase (AR) in porcine lens. The compounds which exhibited potent activity in vitro were also assayed in vivo for inhibitory activity against sorbitol accumulation in the erythrocytes, sciatic nerve and lens of streptozotocin-diabetic rats. The 4-(substituted benzothiazol-2-ylmethyl)-1,4-benzothiazine-2-acetic acid derivatives (2 and 3) showed more potent AR inhibitory activity than did the 4-(4-bromo-2- fluorobenzyl)-1,4-benzothiazine-2-acetic acid derivatives (1). 4-(4,5,7- Trifluorobenzothiazol-2-ylmethyl)-3,4-dihydro-3-oxo-2H-1,4-benzothiazine-2- acetic acid (2q, SPR-210) showed not only a potent AR-inhibitory activity in vitro (IC50 9.5 x 10-9 M) but also a significant reduction in sorbitol accumulation in rat sciatic nerve (ID50 0.1 mg/kg) and lens (ID50 9.8 mg/kg). Optical resolution of the racemic SPR-210 was achieved by means of a diastereomer salt method using (-)-brucine. The biological activities of both enantiomers, (+)- and (-)-SPR-210, were comparable to that of the racemate.
- Aotsuka,Hosono,Kurihara,Nakamura,Matsui,Kobayashi
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p. 1264 - 1271
(2007/10/02)
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- The Synthesis of (3'-Oxo-3',4'-dihydro-2'H-1',4'-benzothiazin-2'-yl)acetic Acid and (3'-Oxo-3',4'-dihydro-2'H-1',4'-benzoxazin-2'-yl)acetic Acid Derivatives
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Reaction of o-aminophenol with various maleic anhydrides gave first 2-hydroxymaleanilic acids (4-(2'-hydroxyphenylamino)-4-oxobut-2-enoic acids) (1), which were then converted into the 3-oxo-1,4-benzoxazines (1d-h) and (3f-l) under mild basic conditions:
- Teitei, Tsutomu
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p. 503 - 510
(2007/10/02)
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