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Cyanoacetic acid reacted selectively with 4-(trifluoromethyl)pyrimidin-2(1Н)-ones with the formation of Michael addition–decarboxylation products in DMSO solution at 85°С and Mannich reaction products when the reagents were fused together under solventfree conditions.

The information related to the methods of the synthesis of 4- and 6-trifluoromethyl-3,4-dihydropyrimidine- 2-ones and their condensed analogs as potent molecular platforms for the synthesis of bioactive compounds has been analyzed and systematized. The role of inter- and intramolecular cyclocondensations of CF3-containing substrates, as well as nucleophilic addition to C=N bond as key steps for construction of 4-trifluorinated derivatives has been emphasized. The major part of this article is devoted to the construction of trifluoromethyldihydropirimidones of a high optical purity and their thioanalogs based on the condensation of the chiral ureas and thioureas. A special attention is paid to asymmetric reactions, which are used for the synthesis of chiral analogs of the anti-HIV drug Efavirenz. It has been noted that Biginelly reaction of the corresponding fluorinated ketoesters is the common way for obtaining 6-trifluoromethylpyrimidones. The method allows obtaining the target products in one stage although it has limitations due to the need to isolate intermediate cyclic products, which in the future should be subjected to dehydration. The effect of the catalyst nature on the course of Biginelly reaction of trifluoromethylated substrates has been analyzed. It has been shown that nucleophilic 3,6-addition to 4-CF3- dihydropyrimidones is effective method for the synthesis of dihydroorotic acid derivatives.

β-Ketoacids reacted with 4-(trifluoromethyl)pyrimidin-2(1Н)-ones according to the mechanism of Michael addition–decarboxylation, forming 4-(2-oxoalkyl)-6-(trifluoromethyl)-3,4-dihydropyrimidin-2-ones.

4-(Trifluoromethyl)pyrimidin-2(1H)-ones react with trimethylsilyl cyanide in the presence of a tertiary amine catalyst to give Michael-like 1,4-conjugate hydrocyanation adducts exclusively at the 3,6-positions. The resulting 2-oxo-6-(trifluoromethyl)-1,2,3,4-tetrahydropyrimidine-4-carbonitriles have been used to synthesize new trifluoromethylated 4,5-dihydroorotic acid analogues and their esters in racemic as well as enantiopure forms by a chiral auxiliary approach. The orthogonal intramolecular C–F···C=O interaction between the fluorine atom of the CF3 group and the carbon atom of the ester group observed in the crystal state may stabilize the sterically unfavourable conformation of the methyl 2-oxo-6-(trifluoromethyl)hexahydropyrimidine-4-carboxylate molecule with axially oriented substituents.

Acid sensing ion channels 1a (ASIC1a) are of crucial importance in numerous physiological and pathological processes in the brain. Here we demonstrate that novel 2-oxo-2H-chromene-3-carboxamidine derivative 5b, designed with molecular modeling approach, inhibits ASIC1a currents with an apparent IC50 of 27 nM when measured at pH 6.7. Acidification to 5.0 decreases the inhibition efficacy by up to 3 orders of magnitude. The 5b molecule not only shifts pH dependence of ASIC1a activation but also inhibits its maximal evoked response. These findings suggest that compound 5b binds to pH sensor of ASIC1a acting as orthosteric noncompetitive antagonist. At 100 nM, compound 5b completely inhibits induction of long-term potentiation (LTP) in CA3-CA1 but not in MF-CA3 synapses. These findings support the knockout data indicating the crucial modulatory role of ASIC1a channels in the NMDAR-dependent LTP and introduce a novel type of ASIC1a antagonists.

Робота присвячена отриманню та дослідженню перетворень нових поліфункціональних фторовмісних синтез-блоків – алкіл N-(3-нітро-1,1,1-трифторопропан-2-іл)карбаматів. Для їх одержання запропонована каталізована триетиламіном реакція аза-Генрі 2,2,2-трифтороетиліденкарбаматів із нітрометаном. Структура синтезованих сполук надійно доведена комплексом спектральних методів, серед яких найбільш доказовими є спектри ЯМР 13С, в яких новоутворений стереогенний атом вуглецю фіксується у вигляді квартету при 63 м.ч. Показано, що при дії на алкіл N-(3-нітро-1,1,1-трифторопропан- 2-іл)карбамати борогідриду натрію в присутності еквімолярної кількості NiCl2.6H2O відбувається селективне відновлення нітрогрупи і утворення відповідних алкіл N-(3-амінопропан-2-іл)карбаматів. Наявність в їх структурі аміногрупи суттєво позначається на хімічних зсувах діастереотопних метиленових протонів, які в спектрах ЯМР 1Н зміщені в область сильного поля приблизно на 2 м.ч. порівняно з нітропохідними. Алкіл N-(3-амінопропан-2-іл)карбамати при кип’ятінні в толуолі в присутності ДБУ піддаються внутрішньомолекулярній циклоконденсації в 4-трифторометилімідазолідин-2-они. В свою чергу, при обробці трет-бутил N-(3-амінопропан-2-іл)карбаматів хлороводнем у діоксані спостерігається легке зняття захисної Boc-групи і утворення 3,3,3-трифторопропан-1,2-діамінів., The paper is devoted to preparation and study of the transformations of novel multifunctional fluorinated synthetic building blocks – alkyl N-(3-nitro-1,1,1-trifluoropropan-2-yl) carbamates. In order to obtain them in high yields the aza-Henry reaction of 2,2,2-trifluoroethylidencarbamates with nitromethane catalyzed by triethylamine has been proposed. The structure of the compounds obtained has been confirmed by spectral methods. Essential elements of the structure corroboration are 13C NMR spectra, in which a signal of the newly formed stereogenic carbon atom is found as a quartet at 63 ppm. It has been shown that the interaction of sodium borohydride with alkyl N-(3-nitro-1,1,1-trifluoropropan-2-yl)carbamates in the presence of the equimolar amount of NiCl2.6H2O leads to selective reduction of the nitro group and formation of the corresponding alkyl N-(3-aminopropan-2-yl)carbamates. The presence of amino group in their structure considerably affects the chemical shifts of diastereotopic methylene protons. Their signals in the 1H NMR spectra are upfield (about 2 ppm difference in comparison with nitro derivatives). Alkyl N-(3-aminopropan-2-yl)carbamates in refluxing toluene in the presence of DBU were easily transformed into 4-trifluorometylimidazolidyn-2-ones by intramolecular cyclization. In its turn, tert-butyl N-(3-aminopropan-2-yl)carbamates when treating with hydrogen chloride in dioxane readily gave 3,3,3-trifluoropropan-1,2-diamines through Boc protecting group cleavage., Работа посвящена получению и исследованию преобразований новых полифункциональных фторсодержащих синтез-блоков – алкил N-(3-нитро-1,1,1-трифторопропан-2-ил)карбаматов. Для их получения предложена катализируемая триэтиламином реакция аза-Генри 2,2,2-трифтороэтилиденкарбаматов с нитрометаном. Строение синтезированных соединений надежно подтверждено комплексом спектральных методов, среди которых наиболее доказательными являются спектры ЯМР 13С, в которых новообразованный стереогенный атом углерода фиксируется в виде квартета при 63 м.д. Показано, что при воздействии на алкил N-(3-нитро-1,1,1-трифторопропан-2-ил)карбаматы боргидрида натрия в присутствии эквимолярного количества NiCl2.6H2O происходит селективное восстановление нитрогруппы и образование соответствующих алкил N-(3-аминопропан-2-ил)карбаматов. Наличие в их структуре аминогруппы существенно сказывается на химических сдвигах диастереотопных метиленовых протонов, которые в спектрах ЯМР 1Н смещены в область сильного поля примерно на 2 м.д. по сравнению с нитропроизводными. N-(3-Аминопропан-2-ил)карбаматы при кипячении в толуоле в присутствии ДБУ подвергаются внутримолекулярной циклизации в 4-трифторометилимидазолидин-2-оны. В свою очередь, при обработке трет-бутил (3-аминопропан-2-ил)карбаматов хлористым водородом в диоксане происходит легкое снятие защитной Boc-группы и образование 3,3,3-трифторопропан-1,2-диаминов.

N-Benzyloxycarbonyl-2,2,2-trifluoroacetimidoyl chloride reacted with pyridin-2-amine derivatives to form substituted 2-trifluoromethyl-4H-pyrido[1,2-a][1,3,5]triazin-4-ones.

A novel synthetic strategy to 4-trifluoromethyl substituted 2-oxo-1,2-dihydropyrimidine-5-carboxylates has been developed based on the cyclocondensation of β-enaminoesters with N-(1-chloro-2,2,2-trifluoroethylidene)carbamates.

Mannich reactions of ethyl 1-aryl-2,2,2-trifluoroethylidenecarbamates and ureas with acetone in the presence of L-proline gave 1-aryl-3-oxo-1-(trifluoromethyl)butylcarbamates and ureas with an enantiomeric excess of 24–54%.

(S)-(+)-4-Amino-4-aryl-5,5,5-trifluoropentan-2-one reacted with aryl isothiocyanates containing electron-withdrawing substituents to give (S)-(−)-1,4-diaryl-6-methyl-4-trifluoromethyl-3,4-dihydropyrimidine-2(1H)-thiones.

(S)-(+)-4-Amino-4-aryl-5,5,5-trifluoropentan-2-ones reacted with ethyl acetoacetate and ethyl trifluoroacetoacetate to give (S)-(+)-6-aryl-3-acetyl(or trifluoroacetyl)-6-trifluoromethyl-5,6-dihydropyridin-2(1H)-ones.

1-Chlorobenzyl isocyanates react with N-arylfumarates with the formation of dialkyl 2-oxo-3,6-diaryl-1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylates that on alkaline hydrolysis are converted into 6-alkoxycarbonyl-1,4-diaryl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylic acids. The condensation of 1-chloro-1-phenyl-2,2,2-trifluoroethyl isocyanate with N-arylfumarates results in dialkyl 6-oxo-2,3-diaryl-2-trifluoromethyl-1,2,3,6-tetrahydropyrimidine-4,5-dicarboxylates.

Acylation of (S)-(−)-4-amino-4-aryl-5,5,5-trifluoropentan-2-ones with chloroacetyl chloride gave the corresponding chloroacetamides which were treated with sodium azide and then with triphenylphosphine to obtain triphenyl-λ5-phosphanylideneaminoacetic acid amides. The latter underwent thermal (boiling toluene) or base-catalyzed (NaOH/MeOH) intramolecular cyclization with elimination of triphenylphosphine oxide and formation of (7S)-(−)-7-aryl-5-methyl-7-trifluoromethyl-1,3,6,7-tetrahydro-2H-1,4-diazepin-2-ones.

A cyclocondensation of disubstituted (thio)ureas and isocyanates derived from enantiomerically enriched 4-amino-4-aryl-5,5,5-trifluoropentan-2-ones affords a novel synthetic access to chiral 4-trifluoromethyl-substituted 3,4-dihydropyrimidin-2(1H)-(thi)ones and 3,4-dihydro-1,3-oxazin-2-ones, respectively.

The condensation of binucleophilic 3-amino-1-arylimino-1H-isoindoles with bifunctional 1-chloro-benzylisocyanates occurs regioselectively resulting in 3,4-dihydro-1,3,5-triazino[2,1-a]isoindol-2-one derivatives. The structures of the synthesized compounds were unambiguously established by NOE experiments.

1-Chlorobenzyl isocyanates react with 4-hydroxy-6-methylpyran-2-one and 4-hydroxycoumarin forming 4-aryl-3,4-dihydro-2H,5H-pyrano(chromeno)[3,4-e][1,3]oxazine-2,5-diones. The reaction of 1-aryl-2,2,2-trifluoro-1-chloroethyl isocyanates with the above substrates gives rise to structurally isomeric 2-aryl-2-trifluoromethyl-2,3-dihydro-2H,5H-pyrano(chromeno)[3,4-e][1,3]-oxazine-4,5-diones.

Reactions of α-chlorobenzyl isocyanates and 1-aryl-2,2,2-trifluoro-1-chloroethyl isocyanates with N,N-disubstituted cyanothioacetamides gave 3,4-dihydro-2H-1,3-thiazin-4-ones and 3-aryl-2-cyano-4,4,4-trifluorobut-2-enethioamides. The effect of substituents in the reactant molecules on the reaction course and product ratio was studied.

The cyclocondensation of 1-chlorobenzyl isocyanates with S, N- and N, N-nitroketeneacetals has been employed to synthesize hitherto-unknown 6-methylthio-5-nitro-3,4-dihydropyrimidin-2(1 H)-ones, 8-nitro-2,3,6,7-tetrahydroimidazo[1,2-c]pyrimidin-5(1 H)-ones and 9-nitro-1,2,3,4,7,8-hexahydro-6 H-pyrimido[1,6-a]pyrimidin-6(1 H)-ones. Substitution of the methylthio group in 6-methylthio-5-nitro-3,4-dihydropyrimidin-2(1 H)-ones provided 6-amino-5-nitro-3,4-dihydropyrimidin-2(1 H)-ones, which exist in tautomeric equilibrium with 4-imino-5-nitro-3,4,5,6-tetrahydropyrimidin-2(1 H)-ones. The compounds obtained, if boiled in dioxane in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), eliminate the nitro groups to give substituted 4-imino-3,4-dihydropyrimidin-2(1 H)-ones.

The regioselective base-catalyzed addition of nitromethane to 2-oxo-4-trifluoromethyl-1,2-dihydropyrimidine-5-carboxylates is reported. It was found that the Michael-like pathway is highly reversible and substantially dominating under conditions of kinetic control (0–5 °C, 10 h) whereas the aza-Henry reaction leads to thermodynamically stable adducts after 8–24 h exposure at room temperature. The adjacent nitro and alkoxycarbonyl groups were exploited to demonstrate the synthetic potential of the obtained products by converting to the isomeric trifluoromethylated pyrrolo[3,4-d]pyrimidine-2,5-diones. With this aim an efficient protocol for selective reduction of nitro-derivatives to the corresponding 4- or 6-aminomethyl-2-oxo-4-trifluoromethyl-1,2,3,4-tetrahydropyrimidine-5-carboxylates and their subsequent thermal cyclocondensations was applied.

The regioselective base-catalyzed addition of nitromethane to 2-oxo-4-trifluoromethyl-1,2-dihydropyrimidine-5-carboxylates is reported. It was found that the Michael-like pathway is highly reversible and substantially dominating under conditions of kinetic control (0–5 °C, 10 h) whereas the aza-Henry reaction leads to thermodynamically stable adducts after 8–24 h exposure at room temperature. The adjacent nitro and alkoxycarbonyl groups were exploited to demonstrate the synthetic potential of the obtained products by converting to the isomeric trifluoromethylated pyrrolo[3,4-d]pyrimidine-2,5-diones. With this aim an efficient protocol for selective reduction of nitro-derivatives to the corresponding 4- or 6-aminomethyl-2-oxo-4-trifluoromethyl-1,2,3,4-tetrahydropyrimidine-5-carboxylates and their subsequent thermal cyclocondensations was applied.

Functionalized 2,3-dihydro-1,3-thiazin-4(1H)-one derivatives have been synthesized by cyclocondensation of 3-alkyl(aryl)amino-2-cyano-3-mercaptoacrylamides with aldehydes and ketones under acidic catalysis. 6-Alkyl(aryl)amino-5-cyano-2,3-dihy- dro-1,3-thiazin-4(1H)-ones, when treated with a dilute solution of potassium hydroxide, are converted into the potassium salts of isomeric compounds, 1-alkyl- (aryl)-5-cyano-6-mercapto-2,3-dihydropyrimidin- 4(1H)-ones. Alkylation of the latter with dimethyl sulfate in situ furnishes 1-alkyl(aryl)-6-alkylthio-5- cyano-2,3-dihydropyrimidin-4(1H)-ones, whereas boiling them in ethanol with an excess of hydrochloric acid leads to starting 2,3-dihydro-1,3-thiazin-4(1H)-ones. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:426–436, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20129

1-Chloroalkyl isocyanates react with imidazole, 4(5)-phenylimidazole, and 4,5-dimethyl(phenyl)-imidazoles to give 5-aryl-5-trifluoromethyl-5,6-dihydro-7H-imidazo[1,5-a]imidazole-7-ones, and with benzimidazole affording 1-aryl-1-trifluoromethyl-1,2-dihydro-3H-imidazo-[1,5-a]benzimidazole-3-ones.

1-Chloroalkyl isocyanates react with 2-R-methylbenzothiazoles [R = CN, C(O)OAlk, 2-benzothiazolyl] in the presence of triethylamine to give 4-R-2,3-dihydro-1H-pyrimido[6,1-b][1,3]benzothiazol-1-ones. The same reaction at elevated temperature in the absence of a base yields isomeric 4-R-2,3-dihydro-1H-pyrimido[6,1-b][1,3]benzothiazol-3-ones. 4-R-1H-Pyrimido[6,1-b][1,3]benzothiazol-1-ones are formed in the reaction of 1,1-dichloroalkyl isocyanates or methyl 1-chloroalkylidenecarbamates with 2-benzothiazolylacetonitrile or bis(2-benzothiazolyl)methane.

N-Benzyloxycarbonyl-2,2,2-trifluoroacetimidoyl chloride reacted with pyridin-2-amine derivatives to form substituted 2-trifluoromethyl-4H-pyrido[1,2-a][1,3,5]triazin-4-ones.

Mannich reactions of ethyl 1-aryl-2,2,2-trifluoroethylidenecarbamates and ureas with acetone in the presence of L-proline gave 1-aryl-3-oxo-1-(trifluoromethyl)butylcarbamates and ureas with an enantiomeric excess of 24–54%.

Cyclization of N-(1-aryl-1-chloro-2,2,2-trifluoroethyl)-N -arylcarbodiimides with 3-substituted 1-phenylpyrazol-5-ones yields 6-aryl-4-arylimino-1-phenyl-6-trifluoromethyl-1,4,5,6-tetrahydropyrazolo[4,3-e][1,3]oxazines. N-(1-Chloroalkyl)carbodiimides are used as 1,3-dielectrophilic components in the synthesis of various nitrogen-containing heterocyclic compounds [2, 3]. In particular, we previously showed that condensation of these reagents with 1,3-diketones (which act as O,Cdinucleophiles) yields 1,3-oxazine derivatives [4]. With the goal of synthesizing relatively difficultly accessible fused pyrazolo[4,3-e][1,3]oxazine systems [5], in the present work we examined reactions of N-(1-aryl-1-chloro-2,2,2-trifluoroethyl)-N -arylcarbodiimides Ia Ic with such O,C-dinucleophiles as 3-substituted 1-phenylpyrazol-5-ones IIa IIc. We have found that N-(1-chloroalkyl)carbodiimides Ia Ic react with 1-phenylpyrazol-5-ones IIa IIc containing an electron-acceptor substituent R in position 3 to afford 3-R-4-aryl-6-arylimino-1-phenyl-4-trifluoromethyl-1,4,5,6-tetrahydropyrazolo[4,3-e][1,3]oxazines IIIa IIIe (Scheme 1). The reactions occur in benzene in the presence of triethylamine at room temperature and take 3 days.

Selective saponification of diester (IIId) succeeds under well-defined conditions; the hydrolysis leads otherwise to a complex mixture of mono- and diacids as well as decarboxylation products.

A cyclocondensation of disubstituted (thio)ureas and isocyanates derived from enantiomerically enriched 4-amino-4-aryl-5,5,5-trifluoropentan-2-ones affords a novel synthetic access to chiral 4-trifluoromethyl-substituted 3,4-dihydropyrimidin-2(1H)-(thi)ones and 3,4-dihydro-1,3-oxazin-2-ones, respectively.

The condensation of binucleophilic 3-amino-1-arylimino-1H-isoindoles with bifunctional 1-chloro-benzylisocyanates occurs regioselectively resulting in 3,4-dihydro-1,3,5-triazino[2,1-a]isoindol-2-one derivatives. The structures of the synthesized compounds were unambiguously established by NOE experiments.

4-Trifluoromethyl-3,4-dihydro-1,3,5-triazino[2,1-a]isoindol-2-ones were prepared by reaction of 1-aryl-1-chloro-2,2,2-trifluoroethyl isocyanates with 3-amino-1-arylimino-1H-isoindoles in the presence of triethylamine. In some events alongside the main product isomeric 2-trifluoromethyl-2,3-dihydro-1,3,5-triazino[2,1-a]isoindol-4-ones were obtained. The regioselectivity of the reaction is affected by sterical and electronic characteristics of substituents and by temperature.

The cyclocondensation of 1-chlorobenzyl isocyanates with S, N- and N, N-nitroketeneacetals has been employed to synthesize hitherto-unknown 6-methylthio-5-nitro-3,4-dihydropyrimidin-2(1 H)-ones, 8-nitro-2,3,6,7-tetrahydroimidazo[1,2-c]pyrimidin-5(1 H)-ones and 9-nitro-1,2,3,4,7,8-hexahydro-6 H-pyrimido[1,6-a]pyrimidin-6(1 H)-ones. Substitution of the methylthio group in 6-methylthio-5-nitro-3,4-dihydropyrimidin-2(1 H)-ones provided 6-amino-5-nitro-3,4-dihydropyrimidin-2(1 H)-ones, which exist in tautomeric equilibrium with 4-imino-5-nitro-3,4,5,6-tetrahydropyrimidin-2(1 H)-ones. The compounds obtained, if boiled in dioxane in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), eliminate the nitro groups to give substituted 4-imino-3,4-dihydropyrimidin-2(1 H)-ones.

By the reaction of 6-aryl(alkyl)amino-5-cyano-2,3-dihydro-1,3-thiazin-4(10)-ones with α-halogenoketones in the presence of triethylamine, 2,3-dihydrothieno[2,3-d]pyrimidin-4(1H)-ones have been synthesized and their acid-catalyzed recyclization to 2,3-dihydrothieno[3,4-d]pyrimidin-4(1H)-ones has been found and studied. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:104–111, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20181

A new convenient approach to the synthesis of N1-sub-stituted 3,4-dihydropyrimidin-2(1H)-ones was developed using the regioselective cyclocondensation of α-chlorobenzyl isocyanates with ethyl N-alkyl(aryl)-β-aminocrotonates. A number of Nl-aryl and N1-alkyl substituted Biginelli compounds difficult to obtain by other methods were prepared with high yields.

6-Azido-1H-pyrazolo[3,4-b]pyridino-5-carbaldehydes react with aromatic amines to give the corresponding N-arylimines which cyclize on heating in boiling toluene to give 6-aryl-1,6-dihydrodipyrazolo[3,4-b:4,3-e]pyridines.