Darlene C. Flores

HALOACETYLATED ENOL ETHERS: 16[5] REGIOSPECIFIC SYNTHESIS OF 5-TRICHLOROMETHYL-PYRAZOLES

ABSTRACT The regiospecific synthesis and isolation of three series of 5-trichloromethyl-pyrazoles 2f–j, 3a–j and 4a–j from the cyclocondensation of 1,1,1-trichloro-4-alkoxy-3-alken-2-ones (1a–f) or trichloroacetyl containing β-diketones (1g–j) with dry hydrazine and phenyl-hydrazine is reported. It was established by 1H- and 13C-NMR spectroscopy that the 5-hydroxy-5-trichloromethyl-4,5-dihydro-1H-pyrazole intermediates 2a–j were formed quantitatively.

Antioxidant and antimicrobial properties of 2-(4,5-dihydro-1H-pyrazol-1-yl)-pyrimidine and 1-carboxamidino-1H-pyrazole derivatives

Cinco derivados de 4-trifluorometil-2-(5-aril-3-stiril-1 H-pirazol-1il)-pirimidinas e seis 5-aril3-estiril-1-carboxamidino-1H-pirazois previamente sintetizados foram avaliados de acordo com suas propriedades antioxidantes e antimicrobianas. Estas atividades foram avaliadas por ensaios de DPPH e HRP/luminol/H 2 O 2 quimioluminescencia e suas atividades antimicrobianas (CIM). Os resultados foram bons para alguns compostos da serie em certas concentracoes em comparacao direta com padroes. Five previously synthesized 4-trifluoromethyl-2-(5-aryl-3-styryl-1 H-pyrazol-1yl)-pyrimidines and six 5-aryl-3-styryl-1-carboxamidino-1H-pyrazole derivatives were screened for their antioxidant proprieties. The antioxidant activities were evaluated by using the DPPH and the HRP/luminol/H 2 O 2 chemiluminescence assay systems and for their antimicrobial activity (MIC). The results were good for those series in some concentration in comparison with the standards.

Efficient synthesis of new 1-[Alkyl(aryl)]-5-(3,3,3-trihalo-2-oxopropylidene)pyrrolidin-2-ones

Reactions of methyl 4-methoxy-6-oxo-7,7,7-trihalo-4-heptenoates 1 and 2 with primary amines RNH2, where R = PhCH2, PhCH2CH2, Ph, 4-MeC6H4, 4-MeOC6H4, 4-ClC6H4, 4-BrC6H4, 2-pyridyl, 5-methyl-3-isoxazolyl, 4-NH2C6H4 affording methyl 4-[alkyl(aryl)amino]-6-oxo-7,7,7-trihalo-4-heptenoates 3, 4, in good yields (57-95%), which suffer quantitative intramolecular cyclocondensation to produce 1-alkyl(aryl)-5-(2-oxo-3,3,3-trihalopropylidene)pyrrolidin-2-ones 5, 6, are reported. The structures of the isolated new products were assigned by means of 1H, 13C NMR measurements and mass spectrometry. The Z and E configuration of compounds 3d and 5b respectively were established from X-ray crystallography.

Synthesis of the omega-brominated alpha-trifluoroacetylcycloalkanones and their isoxazole derivatives

The reactions of a serie of the 2-trifluoroacetyl-1-methoxy-1-cycloalkenes (1a-1e) and 2-trifluoroacetylcycloalkanones (2a-2e) with molecular bromine to obtain w-bromo-a-trifluoroacetylcycloalkanones (3a-3e, 4a) is reported. Was determined that 2-trifluoroacetyl group have established the C-omega as reactive site. The 2-trifluoroacetylcycloalkanones and w-bromo-a-trifluoroacetylcycloalkanones were reacted with hydroxylamine hydrochloride leading to respective 5-trifluoromethyl-5-hydroxy-4,5-dihydro-3,4-polimethyleneisoxazole derivatives (5c-5e and 6c-6e).

A straightforward and efficient synthesis of 3-(pyrimidinyl)propanoates from levulinic acid

The cyclocondensation of methyl 7,7,7-trifluoro-4-methoxy-6-oxo-4-heptenoate and methyl 7,7,7-trichloro-4-methoxy-6-oxo-4-heptenoate, derived from levulinic acid with amidines [NH2CONH2, NH2CR(NH) (R = H, Me, Ph, NH2, SMe and 1H-pyrazol-1-yl), 5-amino-3-methyl1H-pyrazol and 2-aminothiazole] into pyrimidine and pyrimidine-like derivatives as a new type of glutamate-like 3-(trihalomethylatedpyrimidinyl)propanoate is reported. Preparation of 3-(trihalomethylatedpyrimidinyl) propanohydrazides is also described. The synthetic potential of this straightforward protocol was established by the synthesis of fourteen new 3-(pyrimidinyl) propanoates in regular to good yields (38-92%). The structural assignments were based on the analysis of their 1H and 13C nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS) data.

From Levulinic Acid to Biheterocycles: Synthesis of 1-[(5-Hydroxy-5-trifluoromethyl-3-substituted-4,5-dihydro-1H-pyrazol-1-yl)-3-(5-trifluoromethyl-1H-pyrazol-3-yl)propan-1-ones

Abstract We develop an efficient method to synthesize novel propionyl-spaced bisheterocyclic compounds. It entails cyclocondensation of 3-(5-trifluoromethyl-1H-pyrazol-3-yl)propanoyl hydrazide obtained from levulinic acid, with 1,1,1-trifluoro-4-methoxy-3-alken-2-ones proceeding regiospecifically to 1-[(5-trifluoromethyl-5-hydroxy-3-substituted-4,5-dihydro-1H-pyrazol-1-yl)-3-(5-trifluoromethyl-1H-pyrazol-3-yl)propan-1-one derivatives. GRAPHICAL ABSTRACT

Synthesis of fatty trichloromethyl-β-diketones and new 1H-pyrazoles as unusual FAMEs and FAEEs

A sintese eficiente de novas 1,1,1-tricloro-4-metoxi-3-alquen-2-onas graxas [Cl3CC(O)C(R2)=C(R1)OMe, onde R1 = n-hexil, heptil, nonil, undecil, tridecil e R2 = H] e 1,1,1-tricloro-2,4-alkanediones [Cl3CC(O)CHR2C (O) R1, onde R1 = n-pentil e R2 = Me, R1 = Et e R2 = n-butil, R1 = n-butil e R2 = n-propil] e apresentada, com bons rendimentos (85-95%) a partir da acilacao dos respectivos acetais com cloreto de tricloroacetila. As 1,1,1-tricloro-4-metoxi-3-alquen-2-onas e 1,1,1-tricloro-2,4-alkanediones graxas reagem com cloridrato de hidrazina produzindo os respectivos 1H-pirazol-5-carboxilatos, uma classe de novos esteres metilicos (FAMEs) e etilicos (FAEEs) graxos nao comuns. As estruturas moleculares dos compostos sintetizados foram confirmadas por analise elementar e ressonância magnetica nuclear (NMR) de 1H e 13C. As 1,1,1-tricloro-4-metoxi-3-alquen-2-onas graxas e seus derivados 1H-pirazol-5-carboxilatos sao novos oleoquimicos com propriedades diferenciadas e potencialmente interessantes.

Heterocyclization of ω-Bromo-2-trichloroacetyl Cycloalkanones to Isoxazole Derivatives

Abstract A new series of brominated 3,4-polymethylene-5-hydroxy-5-trichloromethyl-4,5-dihydroisoxazoles (2a–d) has been regiospecifically obtained from the reaction of ω-bromo-2-trichloroacetylcycloalkanones with hydroxylamine in 79–87% yield. Dehydration of the 5-hydroxydihydroisoxazoles 2a–d can be effected with concentrated sulfuric acid at 25 °C to give the regioisomeric brominated 3,4-polymethylene-5-trichloromethylisoxazoles (3a–d). In contrast, the dehydration of 5-hydroxydihydroisoxazoles with sulfuric acid in ethanol solution at 65 °C, for transformation of trichloromethyl to carboxyl group, was reproducible only with 9-bromo-3-trichloromethyl-3,3a,4,5,6,7,8,9-octahydrocycloocta[c]isoxazole-3-ol, 2d, leading to isoxazolecarboxylate 4d. The structural assignments of all isolated products are based on the analysis of their 1H and 13C NMR spectral data.

Synthesis, Structure, and Cyclocondensation of the 4,4,4-Trifluoro-3,3-dihydroxy-2-methyl-1-(thien-2-yl)-1-butanone with Hydroxylamine and Hydrazine

The synthesis of 4,4,4-trifluoro-3,3-dihydroxy-2-methyl-1-(thien-2-yl)butan-1-one (3) through acylation of 1,1-dimethoxy-1-(thien-2-yl)propane (1) with trifluoroacetic anhydride and its reactions with hydroxylamine and hydrazine was investigated. X-ray structural analysis of new trifluoromethyl-substituted dielectrophile 3 revealed that this hydrate exists as a racemate with inter- and intramolecular O-H·O bonds. The crystal structure shows alignment along axis b of pair molecules with the same configuration of the O2-H·O1 bond. For 5(3)-trifluoromethyl-4-methyl-3(5)-(thien-2-yl)-1H-pyrazole (4), obtained via cyclocondensation of precursor 2 and hydrazine hydrochloride, X-ray structural analysis indicated that its rings are almost planar (torsion angle N2-C5-C6-C7–5.4°) and that S1 at the thienyl moiety is anti-periplanar to N2 (torsion angle N2-C5-C6-S1 176.01); no disorder effect was observed for the thienyl ring.

Strategies for the Efficient Synthesis of Biheterocyclic 5-[2-(Trifluoromethylheteroaryl)-ethyl]-1,3,4-oxadiazoles from Levulinic Acid

The synthesis of 5-[2-(trifluoromethylheteroaryl)-ethyl]-1,3,4-oxadiazoles derived from levulinic acid is reported. Cyclocondensations [4 + 1] between four different 5-[2-(trifluoromethylheteroaryl) propionylhydrazides derived from methyl 7,7,7-trifluoro-4-methoxy-6-oxo-4-heptenoate obtained from levulinic acid, and electrophilic orthoesters RC(OR)3 (where R = H, Me, Ph) and CS2 were carried out in a mild medium. Good yields (69-96%) of isolated products were obtained. The structures of the new ethylene-spaced biheterocycles were characterized using H and C nuclear magnetic resonance (NMR) spectroscopy and electrospray ionization coupled to tandem mass spectrometric (ESI MS/MS) data.