Syntesis of 2- and 3-chloro-1,4-dihydroxythioxanthen-9-ones

Loskutov, V. A.; Mamatyuk, V. I.; Beregovaya, I. V.

doi:10.1134/s1070428010020168

Cited by 1 publication

(5 citation statements)

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“…IR spectrum, ν, cm -1 : 1679 (C=O), 1658 (C=C). 1 3-Chlorothioxanthene-1,4,9-trione (VII) was synthesized in a similar way from 3-chlorothioxanthenone Vb [13]. Yield nearly quantitative, mp 242-246°C (decomp.).…”

Section: -Chlorothioxanthene-149-trione (Vi)mentioning

confidence: 99%

“…A solution of 2.5 g (4.5 mmol) of ammonium cerium(IV) nitrate in 5 ml of water was added under stirring at room temperature to a solution of 0.6 g (2.2 mmol) of 2-chlorothioxanthenone Va [13] in 30 ml of DMSO, the mixture was stirred for 30 min and poured into ice water, and the precipitate was filtered off. Yield nearly quantitative, mp 202-206°C (decomp.).…”

Section: -Chlorothioxanthene-149-trione (Vi)mentioning

confidence: 99%

“…The mixture was diluted with ice water, and the precipitate (0.13 g) was filtered off and subjected to column chromatography on silica gel using methylene chloride as eluent to isolate 0.03 g (25%) of 3-chloro-1,4-dihydroxythioxanthen-9-one, mp 240-243°C. The product was identified by the TLC and 1 H NMR data in comparison with an authentic sample [13].…”

Section: -Piperidinothioxanthene-149-trione (Ivd)mentioning

confidence: 99%

“…Compound IVa is poorly soluble in that solvent, and it crystallized on the walls of the reaction flask during the process. As shown previously [13], hydrochlorination of quinone I gives a mixture of 2-and 3-chloro-1,4-dihydroxythioxanthen-9-ones, the 3-chloro isomer prevailing.…”

mentioning

confidence: 91%

“…Known quinones of the thioxanthene series are thioxanthene-1,4,9-trione (I), which is available via oxidation of 1,4-dihydroxythioxanthen-9-one (II) with potassium bromate [9], ammonium cerium(IV) nitrate [10], or moist iodous acid [11], and its 2,3-dichloro derivative III obtained by oxidative chlorination of thioxanthenone II with molecular chlorine [12] thionyl chloride [13]. In the present work reactions of quinones I and III with amines were examined with a view to elucidate regioselectivity of the process.…”

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Amination of thioxanthene-1,4,9-trione and its chloro derivatives

Loskutov

2011

Russ J Org Chem

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Thioxanthene-1,4,9-trione and its 2(3)-chloro and 2,3-dichloro derivatives reacted with amines to give the corresponding 2-amino-substituted products.R 1 = H, R 2 = Ph (a); R 1 = H, R 2 = 4-BuC 6 H 4 (b); R 1 = H, R 2 = cyclohexyl (c); R 1 R 2 N = piperidino (d).Quinones are known to react with amines according to nucleophilic 1,4-addition pattern with intermediate formation of aminohydroquinones which undergo oxidation with the initial quinone (or other oxidant) to give aminoquinones [1][2][3]. The site of nucleophile addition to benzo-, naphtho-, and anthraquinones is obvious, whereas formation of different regioisomers is possible in reactions with unsymmetrical quinones, e.g., those in which the quinoid ring is fused to a heteroring or a substituted benzene ring. In these cases, the quinone carbonyl groups are nonequivalent, and each of them may be involved in nucleophile addition at the conjugated bond system. In this respect, nitrogen-containing heterocyclic quinones were studied most thoroughly; the direction of their reactions with amines is determined by the solvent nature, substitution pattern in the substrate, and catalysis by metal salts. A classical example illustrating the above stated is given by 5,8-quinolinequinone and its monochloro derivatives [4]. Unsubstituted 5,8-quinolinequinone reacts with aniline to produce addition products at positions 6 and 7 at a ratio of ~1 : 1 (in ethanol) or 6.5 : 1 (in acetic acid), whereas 6-phenylamino derivative is formed exclusively in the presence of CeCl 3 · 7 H 2 O as catalyst (in ethanol). 6-Chloro-5,8-quinolinequinone in the absence of catalyst reacts mainly according to the addition pattern to form 7-phenylamino derivative, while replacement of the 6-chlorine atom becomes the only process under catalytic conditions. 7-Chloro-5,8-quinolinequinone is converted into 7-chloro-6-phenylamino derivative as the only product both in the absence and in the presence of catalyst. Analogous studies were performed for other nitrogencontaining quinones, such as indole-4,7-quinone [5], isoquinoline-5,8-quinone [6], and phenanthridine-7,10-quinone [7], as well as for 5-substituted 1,4-naphthoquinones [8].There are no published data on the regioselectivity of amination of sulfur-containing heterocyclic quinones. Known quinones of the thioxanthene series are thioxanthene-1,4,9-trione (I), which is available via oxidation of 1,4-dihydroxythioxanthen-9-one (II) with potassium bromate [9], ammonium cerium(IV) nitrate [10], or moist iodous acid [11], and its 2,3-dichloro derivative III obtained by oxidative chlorination of thioxanthenone II with molecular chlorine [12] or

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Section: -Chlorothioxanthene-149-trione (Vi)mentioning

confidence: 99%

Section: -Chlorothioxanthene-149-trione (Vi)mentioning

confidence: 99%

Section: -Piperidinothioxanthene-149-trione (Ivd)mentioning

confidence: 99%

mentioning

confidence: 91%

mentioning

confidence: 99%

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