Bis(trifluoromethyl)-containing 1-azatricycloheptanes

6-Substituted 7-halo-3,3-bis(trifluoromethyl)-2-azabicyclo[2.2.1]heptanes were synthesized by the addition of water, alcohols, and acetic acid to 3-halo-7,7-bis(trifluoromethyl)-1-azatricyclo[2.2.1.0^2,6]heptanes in the presence of H₂SO₄. 5,6-Disubstituted 3,3-bis(trifluoromethyl)-2-azabicyclo[2.2.1]heptanes were prepared by oxymercuration of 3,3-bis(trifluoromethyl)-2-azabicyclo[2.2.1]hept-5-ene.     

Synthesis of 2-amino-5-chloro-3-(trifluoromethyl)benzenethiol and conversion into 4H-1,4-benzothiazines and their sulfones

The synthesis of 2-amino-5-chloro-3-(trifluoromethyl)benzenethiol was achieved by hydrolytic cleavage of 2-amino-6-chloro-4-(trifluoromethyl)benzothiazole which was prepared by cyclization of 4-chloro-2-(trifluoromethyl)phenylthiourea by bromine in chloroform, the phenylthiourea was prepared by the reaction of 4-chloro-2-(trifluoromethyl)aniline with ammonium thiocyanate in hydrochloric acid. Condensation and oxidative cyclization of 2-amino-5-chloro-3-(trifluoromethyl)benzenethiol with β-diketones/β-ketoesters provided 4H-1,4-benzothiazines. Fluorinated sulfones were obtained by oxidation of the corresponding benzothiazines with 30% hydrogen peroxide in glacial acetic acid. The structures of the newly synthesized compounds were confirmed by spectral studies.     

Logistic flexibility in the preparation of isomeric halopyridinecarboxylic acids

Although there are many conceivable ways to funtionalize, and specifically carboxylate, 2-chloro-4-(trifluoromethyl)pyridine optionally at all three vacant positions, it is more straightforward to prepare only the 2-chloro-4-(trifluoromethyl)pyridine-3-carboxylic acid (1) from this precursor and the other 6-chloro-4-(trifluoromethyl)pyridine-2- and -3-carboxylic acids (2 and 3) from a different one, viz. 5-bromo-2-chloro-4-(trifluoromethyl)pyridine. In the same manner, it proved more convenient to convert 5-chloro-2-(trifluoromethyl)pyridine in only two of the corresponding acids (6 and 7) and to make the third one (8) from 3-bromo-5-chloro-2-(trifluoromethyl)pyridine as an alternative starting material. All model substrates for functionalization were readily accessible from the correspondingly substituted chloroiodopyridine through heavy halogen displacement by in situ generated (trifluoromethyl)copper.     

3-Alkenyl-5-chloropyrazoles: expedient synthesis via heterocyclization of 1,1-dichloro-4-halo-1-alken-3-ones with hydrazines

Synthesis of hard-to-reach 5-chloro-3-alkenylpyrazoles was developed via heterocyclization of alkyl-, benzyl- or dialkylhydrazines with 1,1-dichloro-4-halo-1-alken-3-ones obtained from haloacyl chlorides and vinylidene chloride. The reaction process includes the formation of intermediate 5-chloro-3-(1-haloalkyl)pyrazoles followed by dehydrohalogenation.     

Synthesis of new synthons for organofluorine compounds from halothane containing sulfur functional groups

To develop new synthons for the syntheses of organofluorine compounds, the treatment of Halothane, 2-bromo-2-chloro-1,1,1-trifluoroethane, (1) with 4-methylbenzenethiol (2) in the presence of sodium hydride gave 1-chloro-2,2,2-trifluoroethyl 4-methylphenyl sulfide (3), which was oxidized with m-chloroperbenzoic acid (m-CPBA) to the corresponding sulfoxide (4) and sulfone (5). Reaction of 3 and 5 with allyltributyltin in the presence of 2,2'-azobis(isobutyronitrile) (AIBN) gave 1-(trifluoromethyl)-3-butenyl compounds (9, 11). Sulfoxide 4 was decomposed in this condition. The treatment of 3 with allyltrimethylsilane in the presence of Lewis acids gave 1-(trifluoromethyl)-3-butenyl compounds (9) in good yield. This result suggests that 4-methylphenylthio substituent stabilizes the alpha-carbocation effectively, though the trifluoromethyl group destabilizes it strongly. Aromatic compounds similarly reacted with 3 in the presence of titanium(IV) chloride to give 2-aryl-1,1,1-trifluoro-2-(4-methylphenylthio)ethanes. Thus, sulfur compounds derived from Halothane were found to be useful new synthons for organofluorine compounds.     

Synthesis of 2-[3′-(trifluoromethyl)anilino] -5-hydroxynicotinic acid

2-[3′-(Trifluoromethyl)anilino]-5-hydroxynicotinic acid (2) was synthesized by two routes: a) by direct hydroxylation of 2-[3′-(trifluoromethyl)anilino]nicotinie acid (1) ; and b) by the following sequence starting from 2-chloro-3-methyl-5-nitropyridine (3) via 5-amino-2-chloro-3-methylpyridine (4) , 2-ehloro-5-hydroxy-3-methylpyridine (6) , 5-acetoxy-2-chloro-3-methylpyridine (7) , 5-acetoxy-2-chloronicotinie acid (8) , and 2-chloro-5-hydroxynicotinic acid (9). The correlation of 2 with one of the metabolites of 1 has been accomplished, and the identities of both compounds have been proven.     

Synthesis of 2-Substituted 7-Methyl-6-(nitroimidazolyl)thiopurines

2-Substituted 7-methyl-6-(nitroimidazolyl)thiopurines have been synthesized by the reaction of 2-chloro(phenylamino, cycloalkylamino)-7-methyl-6-thiopurines with 5(4)-halo-4(5)-nitroimidazoles and the reaction of 2,6-dichloro-(6-chloro-2-dimethylamino)-7-methylpurines with sodium or ammonium salts of 5(4)-mercapto-4(5)-nitroimidazoles.     

Synthesis and 13C NMR of (trifluoromethyl)hydroxypyrazoles

Reaction of ethyl 4,4,4-trifluoroacetoacetate with methylhydrazine produced not only the previously reported 5-hydroxy-3-(trifluoromethyl)pyrazole 1 but also its unknown isomer the 3-hydroxy-5-(trifluoromethyl)pyrazole 4 . The structure assignments are established based on ¹³C nmr spectra. Compound 1 was converted to 5-chloro-3-(trifluoromethyl)pyrazolecarboxylic acid 3 in two steps.     

Reaction of α-halogen substituted β-ethoxyvinyl trifluoromethyl ketones with 2-aminopyridine: new route to trifluoroacetyl-containing heterocycles

The reaction of α-halosubstituted β-ethoxyvinyl trifluoromethyl ketones with 2-aminopyridine gives 3-trifluoroacetyl imidazo[1,2-a]pyridine and 3-halo-1,1,1-trifluoro-4-(2-pyridinylamino)-3-buten-2-ones. The product ratio depends on the nature of the α-halogen atom and the solvent.     

Bis(trifluoromethyl)-containing 1-azatricycloheptanes

Methods for the synthesis ofanti-3-halo-7, 7-bis(trifluoromethyl)-1-azatricyclo[2.2.1.0^2,6]heptanes by conjugated halogenation of 3,3-bis(trifluoromethyl)-2-azabicyclo[2.2.1]hept-5-ene have been developed. Hydrohalogenation of the synthesized 1-azatricyclic compounds gives exclusively 6,7-dihalo-3,3-bis(trifluoromethyl)-2-azabicyclo[2.2.1]heptanes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1649–1653, September, 1997.     

New regiospecific isothiazole C-C coupling chemistry

Regioselective palladium catalysed coupling reactions are achieved in good to high yields, starting from either 3,5-dichloro- or 3,5-dibromoisothiazole-4-carbonitriles 1 and 2, providing 3-halo-5-(hetero/aryl, alkenyl and alkynyl)isothiazoles 3, 4, 6-9 from Stille couplings, 3-halo-5-(hetero/arylethynyl)isothiazoles 14-19 from Sonogashira and 5,5'-bi(3-chloroisothiazole-4-carbonitrile) (13) from an Ullmann type coupling. 3,5-Dibromoisothiazole-4-carbonitrile 2 is more reactive than the dichloroisothiazole-4-carbonitrile 1 and effective enough for Stille, Negishi and Sonogashira couplings. 5,5-Bi(3-chloroisothiazole-4-carbonitrile) (13) is prepared by a palladium catalysed Ullmann coupling from 3-chloro-5-iodoisothiazole-4-carbonitrile (11). A variety of 3-substituted isothiazoles (3-substituents = Cl, Br, OMs, OTs and OTf) are less reactive and fail to give successful Suzuki couplings at the isothiazole C-3 position. The 3-iodo-5-phenyl-isothiazole-4-carbonitrile (28), prepared via Sandmeyer iodination, participates successfully in Suzuki, Ullmann type, Stille, Negishi and Sonogashira coupling reactions. All products are fully characterized.     

Novel and versatile reactions of trifluoroamine oxide: a new route to polyfluorinated ethers

A series of pyrimidine methyl and polyfluoroalkyl ethers were synthesized from the reactions of trifluoroamine oxide (1) with several 5-substituted uracils in the presence of tetrabutylammonium hydroxide and methanol, 2,2,2-trifluoroethanol (6), or 1H,1H-pentafluoropropanol (7). With 5-(trifluoromethyl)uracil (2), the new ethers formed were 5-fluoro-5-(trifluoromethyl)-6-methoxypyrimidine-2,4-dione (8), 5-fluoro-5-(trifluoromethyl)-6-(trifluoroethoxy)pyrimidine-2,4-dione (9), and 5-fluoro-5-(trifluoromethyl)-6-(1H,1H- pentafluoropropoxy)pyrimidine-2,4-dione (10). With 5-chlorouracil (3), the new ethers 5-chloro-5-fluoro-6-methoxypyrimidine-2,4-dione (11), 5-chloro-5-fluoro-6-(trifluoroethoxy)pyrimidine-2,4-dione (12), and 5-chloro-5-fluoro-6-(1H,1H-pentafluoropropoxy)pyrimidine-2,4-dione (13) were obtained. With 5-fluorouracil (4), the new ethers 5,5-difluoro-6-methoxypyrimidine-2,4-dione (14), 5,5-difluoro-6-(trifluoroethoxy)pyrimidine-2,4-dione (15) and 5,5 difluoro-6-(1H,1H-pentafluoropropoxy)pyrimidine-2,4-dione (16) were found. By reaction of 5-nitrouracil (5), the new ethers 5-nitro-5-fluoro-6 methoxypyrimidine-2,4-dione (17), 5-nitro-5-fluoro-6-(trifluoroethoxy)pyrimidine-2,4-dione (18), and 5-nitro-5-fluoro-6-(1H,1H-pentafluoropropoxy)pyrimidine-2,4-dione (19) were obtained. Each of the new compounds was characterized by using IR, 19F and 1H NMR, and mass spectroscopy, and elemental analysis. A single-crystal X-ray diffraction study of 8 was helpful in confirming compound structure.     

Synthesis, Characterization, and Thermolysis of C(15)N(12)

Synthesis of 1-methyl-2-fluoro-4,5-dicyanoimidazole was done by halogen exchange between 1-methyl-2-bromo-4,5-dicyanoimidazole and potassium fluoride. Halogen exchange between 1-methyl-2-bromo-4,5-dicyanoimidazole and lithium chloride in N-methylpyrrolidinone at 150 degrees C yielded 1-methyl-2-chloro-4,5-dicyanoimidazole, and additional heating to 210 degrees C resulted in the demethylation to yield 2-chloro-4,5-dicyanoimidazole. Thermolyses of the 2-halo-4,5-dicyanoimidazole derivatives (F, Cl) and 1-iodo-2-halo-4,5-dicyanoimidazole derivatives (Cl, Br, I) between 100 and 290 degrees C were found to yield Tris(imidazo)[1,2-a:1,2-c:1,2-e]-1,3,5-triazine-2,3,5,6,8,9-hexacarbonitrile, or HTT, with (C(5)N(4))(3) composition. HTT has been characterized and purified and the crystal structure obtained. Thermolysis of HTT at 490-500 degrees C gives a material with C/N = 1.020. The thermal properties of HTT and its decomposition products show thermal stability to 350 degrees C.     

Process development and large-scale synthesis of NK1 antagonist

A scaleable synthetic route is described to obtain 2-(4-acetylpiperadin-1-yl)-6-[3,5-bis(trifluoromethyl)phenylmethyl]-4-(2-methylphenyl)-6,7,8,9-tetrahydro-5H-pyrimido[4,5-b][1,5]oxazocin-5-one (1, KRP-103) as a neurokinin (NK)(1) antagonist. The key step in the synthesis is the intramolecular cyclization of N-[3,5-bis(trifluoromethyl)phenylmethyl]-N-(3-hydroxypropyl)-4-chloro-6-(2-methylphenyl)-2-methylthiopyrimidine-5-carboxamide (15) which was obtained by amide formation between 4-(2-methylphenyl)-2-methylthio-6-oxo-1,6-dihydropyrimidine-5-carboxylic acid (8) and 3-[3,5-bis(trifluoromethyl)phenylmethylamino]-1-propanol (3). Treatment of 15 with 1,8-diazabicyclo[5,4,0]undec-7-ene provided 6-[3,5-bis(trifluoromethyl)phenylmethyl]-4-(2-methylphenyl)-2-methylthio-6,7,8,9-tetrahydro-5H-pyrimido[4,5-b][1,5]oxazocin-5-one (6). This intermediate (6) is transformed into the candidate compound (1) by two steps; oxidation, and substitution reaction of the resultant sulfone (7) with 1-acetylpiperazine. This synthetic method is free of chromatographic purification and is amenable to large scale synthesis.     

Syntheses Based on 4-Chloro-1-[3,5-di(trifluoromethyl)phenyl]-, 4-Chloro-1-(2,4-difluorophenyl)-5-formyl-3-methyl-6,7-dihydroindazoles,and 4-Chloro-5-formyl-3-methyl-1-(2-pyridyl)-6,7-dihydroindazoles

Vilsmeier formylation of 1-[3,5-di(trifluoromethyl)phenyl]- and 1-(2,4-difluorophenyl)-3-methyl-4-oxo-4,5,6,7-tetrahydroindazoles gave the corresponding 1-aryl-4-chloro-5-formyl-3-methyl-6,7-dihydroindazoles. Reaction of the latter with amidines, o-phenylenediamine, hydrazine, or hydroxylamine gave a series of 1-aryl-3-methyl-6,6-dihydroindazoles annelated at positions 4 and 5. The reaction of 4-chloro-5-formyl-3-methyl-1-(2-pyridyl)-6,7-dihydroindazole with substituted anilines gave 5-arylaminomethylene-4-oxo- or 5-arylaminomethylene-4-arylimino-3-methyl-1-(2-pyridyl)-4,5,6,7-tetrahydroindazoles depending on the molar ratio of reagents and the nucleophilicity of the amines.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 740–750, May, 2005.     

Preparation and steric structure of 2-Alkoxy-2,5-dioxo-4,4-bis(trifluoromethyl)-7(8)-chloro-1,3,2λ5-benzodioxaphosphepins

The reaction of hexafluoroacetone with 2-alkoxy-6(7)-chloro-1,3,2-benzodioxaphosphorin-4-ones yielded 7-and 8-chloro-substituted 2-alkoxy-2,5-dioxo-4,4-bis(trifluoromethyl)-1,3,2λ⁵-benzodioxaphosphepines. Their steric structure was studied by single-crystal X-ray diffraction. The effect of fluorinated substituents on the crystal packing of the benzophosphepines was demonstrated. Hydrolysis of these compounds gave the corresponding 4-and 5-chloro-substituted 2-(2-hydroxyphenyl)-2-oxo-1,1-bis(trifluoromethyl)-ethanols; the structure of 2-(2-hydroxy-5-chlorophenyl)-2-oxo-1,1-bis(trifluoromethyl)ethanol was also proved by single-crystal X-ray diffraction.     

Synthesis of 7-methyl-6-(nitroimidazolyl)thiopurines

We have studied the reactions of 7-methyl-6-thiopurine with 5(4)-halo-4(5)-nitroimidazoles and 6-chloro-7-methylpurine with sodium and ammonium salts of 5-mercapto-4-nitroimidazoles. We have obtained a series of 7-methyl-6-(nitroimidazolyl)thiopurines not previously described in the literature.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 217–220, February, 2000.     

Antifungal Activity of Salicylanilides and Their Esters with 4-(Trifluoromethyl)benzoic Acid

Searching for novel antimicrobial agents still represents a current topic in medicinal chemistry. In this study, the synthesis and analytical data of eighteen salicylanilide esters with 4-(trifluoromethyl)benzoic acid are presented. They were assayed in vitro as potential antimycotic agents against eight fungal strains, along with their parent salicylanilides. The antifungal activity of the presented derivatives was not uniform and moulds showed a higher susceptibility with minimum inhibitory concentrations (MIC) 3 0.49 μmol/L than yeasts (MIC 3 1.95 μmol/L). However, it was not possible to evaluate a range of 4-(trifluoromethyl)benzoates due to their low solubility. In general, the most active salicylanilide was N-(4-bromophenyl)-4-chloro-2-hydroxybenzamide and among esters, the corresponding 2-(4-bromophenylcarbamoyl)-5-chlorophenyl 4-(trifluoromethyl) benzoate exhibited the lowest MIC of 0.49 μmol/L. However, the esterification of salicylanilides by 4-(trifluoromethyl)benzoic acid did not result unequivocally in a higher antifungal potency.     

Antimycobacterial activity of salicylanilide benzenesulfonates

A series of eighteen novel esters of salicylanilides with benzenesulfonic acid were designed, synthesized and characterized by IR, 1H-NMR and 13C-NMR. They were evaluated in vitro as potential antimycobacterial agents towards Mycobacterium tuberculosis, Mycobacterium avium and two strains of Mycobacterium kansasii. In general, the minimum inhibitory concentrations range from 1 to 500 μmol/L. The most active compound against M. tuberculosis was 4-chloro-2-(4-(trifluoromethyl)phenylcarbamoyl)-phenyl benzenesulfonate, with MIC of 1 μmol/L and towards M. kansasii its isomer 5-chloro-2-(4-(trifluoromethyl)phenylcarbamoyl)phenyl benzenesulfonate (MIC of 2-4 μmol/L). M. avium was the less susceptible strain. However, generally, salicylanilide benzenesulfonates did not surpass the activity of other salicylanilide esters with carboxylic acids.     

Reactions of arenediazonium tetrafluoroborates with 3-chloro-2-methylpropene in the presence of potassium chloride,bromide, and thiocyanate

Arenediazonium tetrafluoroborates reacted with 3-chloro-2-methylpropene in the presence of potassium chloride, bromide, and thiocyanate to give the corresponding 1-aryl-3-chloro-2-halo(thiocyanato)-2-methylpropanes. The presence of a copper salt is a necessary condition for the reaction to occur. The yields of the corresponding 1-aryl-3-chloro-2-halo-2-methylpropanes in the Meerwein reaction were approximately twice as low. Introduction of a methyl group to C2 in the 3-chloropropene molecule does not change the reaction regioselectivity.