1,4-Benzothiazines, Dihydro-1,4-benzothiazines, and Related Compounds.

Brown, Charles A.; Davidson, Robert M.

doi:10.1016/s0065-2725(08)60919-8

Cited by 38 publications

(9 citation statements)

References 96 publications

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“…Another central point emerging from the present results is that not all the ''benzothiazine'' units supposed to contribute to the pheomelanin chromophore exhibit absorption spectra entirely consistent with the observed features of the final pigments (26). In particular, those structural components based on the 2H-1,4-benzothiazine ring system or the trichochrome skeleton would exhibit absorption maxima at relatively higher wavelengths than 305 nm, where the most characteristic feature of the pheomelanin chromophore occurs.…”

Section: Resultsmentioning

confidence: 57%

The “Benzothiazine” Chromophore of Pheomelanins: A Reassessment^†

Napolitano

Lucia

Panzella

et al. 2007

Photochem & Photobiology

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The characteristic absorption and photochemical properties of pheomelanins are generally attributed to "benzothiazine" structural units derived biogenetically from 5-S-cysteinyldopa. This notion, however, conveys little or no information about the structural chromophores responsible for the photoreactivity of pheomelanins. At pH 7.4, natural and synthetic pheomelanins show a defined maximum around 305 nm, which is not affected by reductive treatment with sodium borohydride, and a monotonic decrease in the absorption in the range 350-550 nm. These features are not compatible with a significant proportion of structural units related to 2H-1,4-benzothiazine and 2H-1,4-benzothiazine-3-carboxylic acid, the early borohydride-reducible pheomelanin precursors featuring absorption maxima above 340 nm. Rather, these features would better accommodate a contribution by the nonreducible 3-oxo-3,4-dihydrobenzothiazine (lambdamax 299 nm) and benzothiazole (lambdamax 303 nm) structural motifs, which are generated in the later stages of pheomelanogenesis in vitro. This conclusion is supported by a detailed liquid chromatography/UV and mass spectrometry monitoring of the species formed in the oxidative conversion of 5-S-cysteinyldopa to pheomelanin, and would point to a critical reassessment of the commonly reported "benzothiazine" chromophore in terms of more specific and substantiated structural units, like those formed during the later stages of pheomelanin synthesis in vitro.

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Section: Resultsmentioning

confidence: 57%

The “Benzothiazine” Chromophore of Pheomelanins: A Reassessment^†

Napolitano

Lucia

Panzella

et al. 2007

Photochem & Photobiology

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“…11 Carbostyril 12 and dimedone 13 constitute a unique group of compounds due to the simultaneous presence of characteristic features such as a β-diketone group as a starting material. Thazines are known to exhibit various types of biological activities such as Ca 2+ antagonist; blood platelet aggregation inhibitors; 14 and antipsychotic, 15 antiviral, 16 antimicrobial, 17 and antihypertensive 18 agents. Similarly, the thiadiazine nucleus is a versatile pharmacophore, which exhibits a wide variety of biological activity.…”

Section: Introductionmentioning

confidence: 99%

A Facile and Rapid Method for Preparation of Thiazine and Thiadiazine Derivatives by Sonication Technique

Dabholkar¹,

Ansari²

2010

Phosphorus, Sulfur, and Silicon and the Related Elements

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Ultrasound accelerated synthesis of 2,3-(substituted)benzo-1,4-thiazino[5,6-b]-4H-9H-7-methyl-10-oxoquinolines (4), 7-substituted-2,2-dimethyl-2,3-dihydro-1H,10H-phenothiazin-4-one (5), 4-substituted-3,9, 10-trihydro-11-oxo-quinolino[2,3-b]-1,3,4-thiadiazino[2,3-d]-1,2,4-triazole (6), and 7,7-dimethyl-7,8-dihydro-3H,5H,6H-1,2,4-triazolo[3,4-b][1,3,4] benzothiadiazin-9-one (7) from carbostyril and dimedone using sulfur powder and iodine as a catalyst in THF is reported. The structures of the compounds have been elucidated on the basis of spectral and elemental analysis.

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“…2H-1,4-Benzothiazine derivatives have attracted much interest in modern society due to their biological properties [1]. On the other hand, 1,2,4-triazole derivatives are one of the most widely used fungicides due to their high efficiency, low toxicity, and absorbent properties [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

“…Ar-H), 7.03 (1H, dd, J = 8.8 Hz and J = 2.8 Hz, Ar-H), 7.18-7.27 (2H, m, Ar-H), 7.42 (1H, d, J = 7.6 Hz, Ar-H), 7.69(1H, s, triazole-H), 7.74 (1H, d, J = 2.4, Ar-H), 7.87 (1H, s, triazole-H); 13 [1,4] (1H-1,2,4-triazol-1-yl) …”

mentioning

confidence: 99%