A Novel and Simple Synthesis of 2-(Trifluoromethyl)-4<i>H</i>-thiochromen-4-ones

Usachev, Boris I.; Sosnovskikh, Vyacheslav Ya.; Shafeev, M. A.; Röschenthaler, Gerd‐Volker

doi:10.1080/10426500590912259

Cited by 16 publications

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“…Taking into account the above results, it was of interest to evaluate the reactivity of 2-trifluoromethyl-4H-thiochromen-4-ones (1-thiochromones 11a, b) [17]. We anticipated that these compounds due to their similar structure might undergo nucleophilic 1,4-addition reaction giving the corresponding Michael adducts.…”

Section: Resultsmentioning

confidence: 98%

Nucleophilic trifluoromethylation of RF-containing 4-quinolones, 8-aza- and 1-thiochromones with (trifluoromethyl)trimethylsilane

Sosnovskikh¹,

Usachev²,

Sevenard

et al. 2005

Journal of Fluorine Chemistry

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Section: Resultsmentioning

confidence: 98%

Nucleophilic trifluoromethylation of RF-containing 4-quinolones, 8-aza- and 1-thiochromones with (trifluoromethyl)trimethylsilane

Sosnovskikh¹,

Usachev²,

Sevenard

et al. 2005

Journal of Fluorine Chemistry

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“…Интересно, что тиоаналог хромона 1а, 2-трифторметил-4Н-тиохромен-4-он 11 [16], а также его ациклический ана-лог -4,4,4-трифтор-1-фенил-2-бу-тен-1-он 12 -реагируют с реагентом Рупперта в аналогичных условиях ис-ключительно по пути 1,2-присоединения с образованием триметилсилильных производных 13 и 14 [6,15] (схема 8).…”

Section: In Russianunclassified

“…As a result, 8-azachromanones were isolated only with the moderate yield (27-35 %). At the same time, 2-trifl uoromethyl-3-chlorochromone gives the expected Michael adduct 10 in 58 % yield (Scheme 7).It is interestingly, that thioanalogue of chromone 1a, 2-trifl uoromethyl-4H--thiochromen-4-one 11 [16] and its acyclic analogue, 4,4,4-trifl uoro-1-phenyl-2-butene-1-one 12, react with Ruppert's reagent Scheme 6 Scheme 7 33 under the same conditions exclusively towards 1,2-addition with the formation of trimethylsilyl derivatives 13 and 14 [6,15] (Scheme 8).Th e presence of the electron withdrawing R F group at the β-C-atom of enone system is desirable, but not indispensable, if to carry out the reaction in the presence of bulky Lewis acids, which under coordination at the carbonyl oxygen atom complicate 1,2-addition and increase the electrophilicity of the β-C atom. So, in the presence of tris(2,6-diphenylphenoxide) aluminum and Me 4 NF 1,4-trifl uoromethylation of cyclohex-2-enone, chromone and coumarin could exercise and obtain the compounds 15-17 in 35-55 % yields [17] (Scheme 9).…”

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confidence: 94%

“…Отметим, что в последнем случае региоселектив-ность падает и соотношение продуктов 1,4-и 1,2-присоединения составляет ~3: 2, в результате чего 8-азахроманоны 9 были выделены лишь с умеренным вы-ходом (27-35 %). В то же время 2-три-фторметил-3-хлорхромон дает ожидае-мый аддукт Михаэля 10 с выходом 58 % (схема 7).Интересно, что тиоаналог хромона 1а, 2-трифторметил-4Н-тиохромен-4-он 11 [16], а также его ациклический ана-лог -4,4,4-трифтор-1-фенил-2-бу-тен-1-он 12 -реагируют с реагентом Рупперта в аналогичных условиях ис-ключительно по пути 1,2-присоединения с образованием триметилсилильных производных 13 и 14 [6,15] (схема 8).Присутствие электроноакцепторной R F -группы при β-С атоме еноновой си-стемы желательно, но не обязательно, если проводить реакцию в присутствии объемных кислот Льюиса, которые, ко-ординируясь по карбонильному атому кислорода, затрудняют 1,2-присоеди-нение и повышают электрофильность β-С атома. Так, в присутствии трис(2,6-дифенилфеноксида) алюминия и Me 4 NF удается осуществить 1,4-трифтормети-лирование циклогекс-2-енона, хромона Схема 5…”

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“…It is interestingly, that thioanalogue of chromone 1a, 2-trifl uoromethyl-4H--thiochromen-4-one 11 [16] and its acyclic analogue, 4,4,4-trifl uoro-1-phenyl-2-butene-1-one 12, react with Ruppert's reagent Scheme 6 Scheme 7 33 under the same conditions exclusively towards 1,2-addition with the formation of trimethylsilyl derivatives 13 and 14 [6,15] (Scheme 8).…”

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Nucleophilic conjugate trifluoromethylation of chromones and activated alkenes under the action of Ruppert’s reagent

Sosnovskikh

Roshentaler

2017

Chim.Tech.Acta

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Nucleophilic conjugate tri uoromethylation of chromones and activated alkenes under the action of Ruppert's reagentThis review summarizes data on the reactions of chromones and activated alkenes with trimethyl(tri uoromethyl)silane (Ruppert's reagent), which occures as a nucleophilic 1,4-tri uoromethylation with high regioselectivity and good yields. The most important chemical properties of the formed products are also considered.Key words: chromones; activated alkenes; nucleophilic 1,4-trifluoromethylation; trimethyl(tri uoromethyl)silane. Received: 28.02 .2017; accepted: 03.03.2017; published: 14.04 Sosnovskikh V. Ya., Roschenthaler G.-V. Chimica Techno Acta. 2017. Vol. 4, No. 1. P. 29-44. ISSN 2409-5613 DOI: 10.15826/chimtech.2017 30 Th e nucleophilic trifl uoromethylation of organic compounds is complicated by the instability of free trifl uoromethyl anion, which easily breaks down into the fl uoride anion and difl uorocarbene [1]. Th e use of trimethyl(trifl uoromethyl)silane (Ruppert's reagent) in the presence of fl uoride anion as an initiator allows to avoid this unwanted reaction and to realize the direct introduction of the CF 3 group to organic substrates. It is well known that the Ruppert's reagent interacts easily with both saturated and α, β-unsaturated carbonyl compounds via 1,2-nucleophilic addition with formation of the corresponding trifl uoromethyl carbinols [2][3][4]. It is important to note that in the case of α, β-unsaturated ketones, the formation of products of nucleophilic 1,4-trifl uoromethylation (Michael addition) was not observed (Scheme 1).Th e fi rst example of the conjugate trifl uoromethylation of α, β-enone system was discovered by us on the example of the reaction R F SiMe 3 (R F = CF 3 , C 2 F 5 ) with 2-trifl uoromethylchromones 1 [5,6]. Monitoring using 19 F NMR spectroscopy showed that chromones 1 in the presence of the nucleophilic initiator Me 4 NF (THF, 0 °C, 4 h) almost quantitatively and with high regioselectively react with CF 3 SiMe 3 towards the way of 1,4-addition, giving trimethylsilyl ethers 2 (the content in the reaction mixture of 1,2-addition products 3 does not exceed 5-10 %). When processing of the reaction mixture with diluted HCl only the products of 1,4-addition 2 are subjected to hydrolysis to give 2-trifl uoromethyl-2-perfl uoroalkylchroman-4-ones 4. As expected, when increasing of the length of the R F group to C 2 F 5 the regioselectivity of the reaction is reduced to 80-85 % (Scheme 2).Th e optimal conditions of 1,4-trifl uoromethylation (Me 4 NF, THF, 0 °C, 24 h) were used by us for the preparative synthesis of chromanones 4a-f, the yields of which ranged 50-86 % (Scheme 3) [6].Currently, this reaction represents the shortest and most eff ective way of synthesis of partially fl uorinated analogues of natural chromanones, chromanes and chromenes 31with gem-dimethyl group at the atom C(2). Th us, 4-oxo-2,2-bis(trifl uoromethyl)chroman-6-carbaldehyde 5a, an analogue of natural lactarochromal, metabolite of Lactarius deliciosus mushrooms [7], in wh...

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A Novel and Simple Synthesis of 2‐(Trifluoromethyl)‐4H‐thiochromen‐4‐ones

Usachev¹,

Sosnovskikh²,

Shafeev³

et al. 2005

ChemInform

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2005 Thiopyran derivatives R 0370 A Novel and Simple Synthesis of 2-(Trifluoromethyl)-4H-thiochromen-4-ones -[Proceedings of the Twenty-First International Symposium on the Organic Sulfur (ISOCS-XXI)]. -(USACHEV, B. I.; SOSNOVSKIKH*, V. Y.; SHAFEEV, M. A.; ROESCHENTHALER, G.-V.; Phosphorus, Sulfur Silicon Relat. Elem. 180 (2005) 5-6, 1315-1319; Dep. Chem., Ural State Univ., Ekaterinburg 620083, Russia; Eng.) -Lindner 35-159

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A Novel and Simple Synthesis of 2-(Trifluoromethyl)-4H-thiochromen-4-ones

Cited by 16 publications

References 6 publications

Nucleophilic trifluoromethylation of RF-containing 4-quinolones, 8-aza- and 1-thiochromones with (trifluoromethyl)trimethylsilane

Nucleophilic trifluoromethylation of RF-containing 4-quinolones, 8-aza- and 1-thiochromones with (trifluoromethyl)trimethylsilane

Nucleophilic conjugate trifluoromethylation of chromones and activated alkenes under the action of Ruppert’s reagent

A Novel and Simple Synthesis of 2‐(Trifluoromethyl)‐4H‐thiochromen‐4‐ones

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