Patrick Campos - Academia.edu (original) (raw)
Papers by Patrick Campos
J Mol Struct, 2009
The crystal structures of four novel analgesic agents, methyl 5-hydroxy-3- or 4-methyl-5-trichlor... more The crystal structures of four novel analgesic agents, methyl 5-hydroxy-3- or 4-methyl-5-trichloro[trifluoro]methyl-4,5-dihydro-1 H-pyrazole-1-carboxylate, have been determined by X-ray diffractometry. The data demonstrated that the molecular packing was stabilized mainly by O sbnd HctdotO hydrogen bonds of the 5-hydroxy and 1-carboxymethyl groups. The 4,5-dihydro-1 H-pyrazole rings were obtained as almost planar structures showing RMS deviation at a range of 0.0052-0.0805 Å. Additionally, computational investigation using semi-empirical AM1 and PM3 methods were performed to find a correlation between experimental and calculated geometrical parameters. The data obtained suggest that the structural data furnished by the AM1 method is in better agreement with those experimentally determined for the above compounds.
Engenharia Agrícola, 2014
ABSTRACT O Estado de Goiás é o segundo maior produtor de cana-de-açúcar do Brasil. Entretanto, ai... more ABSTRACT O Estado de Goiás é o segundo maior produtor de cana-de-açúcar do Brasil. Entretanto, ainda apresenta baixa produtividade, devido principalmente à falta de variedades adaptadas a esta região e ao déficit hídrico típico. Assim, objetivou-se avaliar o desempenho de dezesseis variedades de cana-de-açúcar submetidas à irrigação suplementar no Cerrado. O experimento foi conduzido em Goianésia-GO, em um Latossolo Vermelho-Amarelo Distrófico, de textura argilosa de abril de 2011 a maio de 2012. O delineamento foi em blocos casualizados (Bifatorial 16x5), com 16 tratamentos (variedades): CTC2, CTC4, CTC9, CTC11, CTC15, CTC18, IAC87-3396, IAC91-1099, IACSP94-3046, IACSP94-2094, IACSP94-2101, IACSP95-5000, RB857515, RB92579, RB966928 e SP86-0042; e cinco tempos de avaliação: 113; 145; 174; 203 e 285 dias após o plantio (DAP), com quatro repetições. A irrigação suplementar, por aspersão, correspondeu a uma reposição de 50% da ETc. Os resultados, de cana- planta, apresentaram diferenças significativas entre as variedades avaliadas, destacando-se as variedades CTC9, CTC11, IAC87-3396, IAC91-1099 e SP86-0042, em termos de produtividade e de rendimento industrial. Assim, estas variedades podem ser recomendadas para o cultivo no Cerrado, em regime de irrigação suplementar.
Inorganica Chimica Acta, 2015
This work describes the synthesis and structural analysis of the uranium and vanadium complexes [... more This work describes the synthesis and structural analysis of the uranium and vanadium complexes [(UO 2 )(C 22 H 30 N 6 O 4 )]ÁMeOH (1) and [(VO) 2 (O)(C 30 H 36 N 7 O 6 )]Á3MeOH (2) with ligands obtained from the condensation of pyridoxal and triethylenetetramine. The probable mechanism for the formation of imidazoline rings in these complexes is described in some details. Finally, electrochemical and UV-Vis studies of the dinuclear vanadium complex were also carried out in order to determine the variation in the oxidation states of the metallic centers (VO 2+ /VO 3+ ) in DMSO solution.
Ultrasonics Sonochemistry
The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalome... more The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalomethyl[carboxyethyl] ketones [R(3)C(O)CHC(R(1))OMe, where R(3)=CF(3), CCl(3), CO(2)Et and R(1)=Me, Et, Pr, Bu, i-Pent, CH(2)CH(2)CO(2)Me] with propargyl amines [R(2)NHCH(2)CCH, where R(2)=Pr, PhCH(2)] is reported. Yields, solvents and reaction times needed for reaction completion, by microwave irradiation (MW), conventional thermal heating (TH) and under ultrasound irradiation (US) are compared. The best results were obtained under US irradiation in good to excellent yields (70-93%).
The Open Crystallography Journal, 2010
... Simone S. Amaral, Patrick T. Campos, Josiane M. dos Santos, Liana da S. Fernandes, Marcos AP ... more ... Simone S. Amaral, Patrick T. Campos, Josiane M. dos Santos, Liana da S. Fernandes, Marcos AP Martins, Helio G. Bonacorso and Nilo Zanatta* ... It is important to notice however, that although the ex-perimental data indicates the existence of electronic reso-nance between the ...
![Research paper thumbnail of 2-[5-(2-Methyl-phen-yl)-3-(2-methyl-styryl)-4,5-di-hydro-1H-pyrazol-1-yl]-6-(thio-phen-2-yl)-4-(tri-fluoro-meth-yl)pyrimidine chloro-form monosolvate](https://attachments.academia-assets.com/44419519/thumbnails/1.jpg)
](Acta crystallographica. Section E, Structure reports online, 2014
In the crystal structure of the title compound, C28H23F3N4S·CHCl3, the chloro-form solvate mol-ec... more In the crystal structure of the title compound, C28H23F3N4S·CHCl3, the chloro-form solvate mol-ecules connect the pyrimidine mol-ecules into chains along [101] through weak C-H⋯N and C-H⋯Cl hydrogen-bond inter-actions. There are further connections between adjacent chains through F⋯Cl halogen contacts of 3.185 (3) Å, with the -CF3 group presenting a significant short F⋯F inter-chain distance of 2.712 (4) Å. The five-membered pyrazole ring is approximately planar (r.m.s. deviation = 0.050 Å). The pyrimidine ring makes dihedral angles of 84.15 (8) and 4.56 (8)° with the benzene rings.
Acta Crystallographica Section E Structure Reports Online, 2014
Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.004 Å; R factor = 0.054; wR... more Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.004 Å; R factor = 0.054; wR factor = 0.217; data-to-parameter ratio = 28.0.
Ultrasonics Sonochemistry, 2012
The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalome... more The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalomethyl[carboxyethyl] ketones [R(3)C(O)CHC(R(1))OMe, where R(3)=CF(3), CCl(3), CO(2)Et and R(1)=Me, Et, Pr, Bu, i-Pent, CH(2)CH(2)CO(2)Me] with propargyl amines [R(2)NHCH(2)CCH, where R(2)=Pr, PhCH(2)] is reported. Yields, solvents and reaction times needed for reaction completion, by microwave irradiation (MW), conventional thermal heating (TH) and under ultrasound irradiation (US) are compared. The best results were obtained under US irradiation in good to excellent yields (70-93%).
Synthetic Communications, 2012
Novel 1-aryl-4,4,4-trichloro-1,3-butanediones in good yields (80-97%) were synthesized in one pot... more Novel 1-aryl-4,4,4-trichloro-1,3-butanediones in good yields (80-97%) were synthesized in one pot through acetal acylation with trichloroacetyl chloride followed by acid hydrolysis. Structures of all compounds were elucidated by elemental analysis, mass spectrometry, and 1 H/ 13 C nuclear magnetic resonance (NMR) measurements. The 1 H/ 13 C NMR data showed that trichloromethyl-b-diketones 2a-k in solution are predominantly ketoenol. However, the spectroscopic data from 4,4,4-trichloro-2-methyl-1-phenyl-1,3-butabedione (2l) with methyl substituent between carbonyls showed a bias toward the diketo form in solution. X-ray diffraction of monocrystals from 2g and 2i showed that these compounds are cis-ketoenol tautomers.
![Research paper thumbnail of Molecular structure of pyrazolo[1,5-a]pyrimidines: X-ray diffractometry and theoretical study](https://attachments.academia-assets.com/44419522/thumbnails/1.jpg)
](Journal of Molecular Structure, 2009
The structure of 7-trichloromethyl-2-methylpyrazolo[1,5-a]pyrimidine (1) and 3-bromo-2-methyl-7-(... more The structure of 7-trichloromethyl-2-methylpyrazolo[1,5-a]pyrimidine (1) and 3-bromo-2-methyl-7-(thien-2-yl)pyrazolo[1,5-a]pyrimidine (2) was determined by X-ray diffractometry. The crystal packing for compounds 1 and 2 was discussed in terms of inter-and intramolecular interactions. Compound 1 showed the intramolecular interaction of pyrazole nitrogen and trichloromethyl chlorine (NÁ Á ÁCl), the intermolecular interactions of pyrimidine nitrogen and chlorine (NÁ Á ÁCl) and p-p interaction between pyrazole ring-centroid. Compound 2 showed the intramolecular interaction of nitrogen of pyrazole and thienyl sulfur (NÁ Á ÁS), the intermolecular interactions of nitrogen of pyrimidine and thienyl sulfur (NÁ Á ÁS) and p-p interaction between pyrimidine and pyrazole ring-centroid. Selected crystallographic data are compared with corresponding semi-empirical AM1 data.
Journal of Molecular Structure, 2010
The crystalline structure of four enaminones [R 1 C(O)CH@C(Me)NR 2 R 3 , where R 1 = CCl 3 , R 2 ... more The crystalline structure of four enaminones [R 1 C(O)CH@C(Me)NR 2 R 3 , where R 1 = CCl 3 , R 2 = H, R 3 = Bn (1); R 1 = CHCl 2 , R 2 = H, R 3 = Bn (2); R 1 = CCl 3 , R 2 , R 3 = A(CH 2 ) 4 A (3); R 1 = CHCl 2 , R 2 , R 3 = A(CH 2 ) 2 AOA(CH 2 ) 2 A (4)] were determined by X-ray diffraction. It was found that compounds 1-4 adopted the enaminone tautomeric form. Compounds 1 and 2 displayed intramolecular hydrogen bonds (2.658 6 d (NÁ Á ÁO) P 2.726), which are associated with the presence of resonance-assisted hydrogen bonds (RABHs). The bond length data implicated that p-delocalization in 3 and 4 was reduced in comparison to 1 and 2 and this can be interpreted as some gain of the aromatic character in the chelate form. In addition, it was shown that the crystal packing of these enaminones is governed by CAHÁ Á ÁO, CAHÁ Á ÁCl, ClÁ Á ÁCl weak interactions and these interactions presents interatomic distances in accordance with the reported van der Waals radii of the atoms involved. The energy of these intermolecular interactions was calculated as a difference in energy between the complex on the one hand and the sum of isolated monomers on the other. The energetic contributions of each interaction to the stability of the crystalline packing were determined, firstly for each interaction independently and secondly, for all interactions simultaneously. The additive effect was verified by the fact that the sum of all individual energetic contributions resulted in the same stability as that found when the energetic contribution of all interactions was calculated simultaneously.
Journal of Molecular Structure, 2006
Crystal structure of 4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid benzyl... more Crystal structure of 4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid benzyl ester has been solved by X-ray diffraction. The crystals are triclinic, space group P 1, with aZ5.4435(18) Å , bZ12.248(2) Å , cZ13.6769(15) Å , aZ70.274(12)8, bZ81.630(15)8, gZ 77.60(2)8, ZZ2 and RZ0.0519. The molecules are strongly linked in dimers by hydrogen bonds, forming rings with R 2 2 ð10Þ as the graph descriptor. The pyrrolic ring, slightly distorted from the C 2v symmetry, is almost planar. This plane makes an angle of 75.5(1)8 with the L.S. plane containing the methoxy-carbonyl group and an angle of 13.6(1)8 with the L.S. plane containing the benzyl group. The internal cohesion of the crystal is supported by three C-H.p intermolecular interactions, with H.Cg (ring centroid) distances ranging from 3.060 to 3.377 Å . Several calculations were performed for the dimer such as density functional theory with a hybrid functional B3LYP, semi-empirical self-consistent field (AM1 and PM3) and self-consistent field molecular orbital Hartree-Fock (SCF-MO HF) method. The latter calculation was repeated for the isolated molecule. In all cases the minimum of the energy is achieved with the substituents assuming a more perpendicular position to the central aromatic ring than is experimentally observed. q
Journal of Molecular Structure, 2010
The structure of three 1-cyanoacetyl-3-alkyl[aryl]-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyr... more The structure of three 1-cyanoacetyl-3-alkyl[aryl]-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazoles (1-3) has been determined by X-ray diffractometry. The 4,5-dihydro-1H-pyrazole rings were obtained as almost planar structures showing RMS deviation at a range of 0.0196-0.0736 Å. The data demonstrate that the molecular packing is dependent on the substituent present in each molecule. In addition, a computational investigation using semi-empirical AM1 and RM1 methods was performed in order to investigate the correlation between experimental and calculated geometrical parameters. The data obtained suggest that the structural data furnished by the AM1 method is in better agreement with those experimentally determined for the above compounds. An analysis of the p-electron delocalization by HOMA calculations indicate that there is a hyperconjugation effect in the imine group toward to phenyl group at ring 3-position of compound 2, and that this resonance effect decrease in compounds 1 and 3. In addition, it was showed that bond N(1) and C(6) do not have an amide character. Thus, the O(6)-C(6)-N(1)-N(2)-C(3) fragment is not completely delocalized mainly due to the low p-electron delocalization in N(1)-N(2) bond for all compounds.
Journal of Molecular Structure, 2011
Abstract The X-ray diffraction data determined for eight 3-(R 3), 4-(R 4), 4, 4-(R 4/R 4'... more Abstract The X-ray diffraction data determined for eight 3-(R 3), 4-(R 4), 4, 4-(R 4/R 4') and/or 5-(R 5) 5-hydroxy-4, 5-dihydroisoxazoles [where R 3= Ph, R 4/R 4'= H/H, R 5= CCl 3 (1); R 3= 4-Br-C 6 H 4, R 4/R 4'= H/H, R 5= CCl 3 (2); R 3= thien-2-yl, R 4/R 4'= H/H, R 5= CCl 3 ( ...
Journal of Molecular Structure, 2011
The crystalline structure of five 3-(R3) and/or 5-(R5)-substituted 7-trichloromethyl-2-methylpyra... more The crystalline structure of five 3-(R3) and/or 5-(R5)-substituted 7-trichloromethyl-2-methylpyrazolo [1, 5-a] pyrimidines [where R3, R5= H, Pr (1); Br, H (2); Br, Me (3); H, H (4); and H, Me (5)] were studied from X-ray diffractometry data. It was found that compounds ...
![Research paper thumbnail of Structural studies of 2-methyl-7-substituted pyrazolo[1,5-a]pyrimidines](https://attachments.academia-assets.com/44419516/thumbnails/1.jpg)
](Journal of Heterocyclic Chemistry, 2010
Six pyrazolo[1,5-a]pyrimidines bearing a 7-trifluoromethyl (three compounds), a 7-trichloromethyl... more Six pyrazolo[1,5-a]pyrimidines bearing a 7-trifluoromethyl (three compounds), a 7-trichloromethyl (two compounds), and a 7-ethoxycarbonyl (one compound) have been structurally characterized. The new X-ray structures of 2-methyl-5-(p-bromophenyl)-7-trifluoromethylpyrazolo[1,5-a]pyrimidine (3) and 2-methyl-7-trichloromethylpyrazolo[1,5-a]pyrimidine (4) are reported. The combined use of GIAO/ B3LYP/6-311þþG(d,p) calculations with NMR spectroscopy in solution and in the solid state allows to establish some general rules that can be useful for characterizing related compounds. Compounds 3 and 4 present in the solid-state interesting intra-and intermolecular halogen bonds.
Journal of Chemical Crystallography, 2012
The trichloroacetoamidoxime was synthesized following the principles of green chemistry in excell... more The trichloroacetoamidoxime was synthesized following the principles of green chemistry in excellent yield (90 %). This compound crystallizes in the orthorhombic system with space group P2 1 2 1 2 1 and the cell parameters are a = 5.7353 (3), b = 10.5167 (8) Å , c = 21.4787 (16) Å , a, b and c = 90°, V = 1295.52 (15) Å 3 , Z = 4. The final residual factor is R 1 = 0.0429, wR 2 = 0.0884. The presence of the intermolecular hydrogen bonds generates pseudo rings of five members between two molecules that indicate the amido oxime conformation for trichloroacetoamidoxime.
Arkivoc, 2009
... Preparation of trichloroacetoamidoxime in aqueous media and application in one pot synthesis ... more ... Preparation of trichloroacetoamidoxime in aqueous media and application in one pot synthesis of 1,2,4-oxadiazoles Lizandra C. Bretanha, a Dalila Venzke, a Patrick T. Campos, b Anaí Duarte, a Marcos AP Martins, b Geonir M. Siqueira, a * and Rogério A. Freitag a * ...
J Mol Struct, 2009
The crystal structures of four novel analgesic agents, methyl 5-hydroxy-3- or 4-methyl-5-trichlor... more The crystal structures of four novel analgesic agents, methyl 5-hydroxy-3- or 4-methyl-5-trichloro[trifluoro]methyl-4,5-dihydro-1 H-pyrazole-1-carboxylate, have been determined by X-ray diffractometry. The data demonstrated that the molecular packing was stabilized mainly by O sbnd HctdotO hydrogen bonds of the 5-hydroxy and 1-carboxymethyl groups. The 4,5-dihydro-1 H-pyrazole rings were obtained as almost planar structures showing RMS deviation at a range of 0.0052-0.0805 Å. Additionally, computational investigation using semi-empirical AM1 and PM3 methods were performed to find a correlation between experimental and calculated geometrical parameters. The data obtained suggest that the structural data furnished by the AM1 method is in better agreement with those experimentally determined for the above compounds.
Engenharia Agrícola, 2014
ABSTRACT O Estado de Goiás é o segundo maior produtor de cana-de-açúcar do Brasil. Entretanto, ai... more ABSTRACT O Estado de Goiás é o segundo maior produtor de cana-de-açúcar do Brasil. Entretanto, ainda apresenta baixa produtividade, devido principalmente à falta de variedades adaptadas a esta região e ao déficit hídrico típico. Assim, objetivou-se avaliar o desempenho de dezesseis variedades de cana-de-açúcar submetidas à irrigação suplementar no Cerrado. O experimento foi conduzido em Goianésia-GO, em um Latossolo Vermelho-Amarelo Distrófico, de textura argilosa de abril de 2011 a maio de 2012. O delineamento foi em blocos casualizados (Bifatorial 16x5), com 16 tratamentos (variedades): CTC2, CTC4, CTC9, CTC11, CTC15, CTC18, IAC87-3396, IAC91-1099, IACSP94-3046, IACSP94-2094, IACSP94-2101, IACSP95-5000, RB857515, RB92579, RB966928 e SP86-0042; e cinco tempos de avaliação: 113; 145; 174; 203 e 285 dias após o plantio (DAP), com quatro repetições. A irrigação suplementar, por aspersão, correspondeu a uma reposição de 50% da ETc. Os resultados, de cana- planta, apresentaram diferenças significativas entre as variedades avaliadas, destacando-se as variedades CTC9, CTC11, IAC87-3396, IAC91-1099 e SP86-0042, em termos de produtividade e de rendimento industrial. Assim, estas variedades podem ser recomendadas para o cultivo no Cerrado, em regime de irrigação suplementar.
Inorganica Chimica Acta, 2015
This work describes the synthesis and structural analysis of the uranium and vanadium complexes [... more This work describes the synthesis and structural analysis of the uranium and vanadium complexes [(UO 2 )(C 22 H 30 N 6 O 4 )]ÁMeOH (1) and [(VO) 2 (O)(C 30 H 36 N 7 O 6 )]Á3MeOH (2) with ligands obtained from the condensation of pyridoxal and triethylenetetramine. The probable mechanism for the formation of imidazoline rings in these complexes is described in some details. Finally, electrochemical and UV-Vis studies of the dinuclear vanadium complex were also carried out in order to determine the variation in the oxidation states of the metallic centers (VO 2+ /VO 3+ ) in DMSO solution.
Ultrasonics Sonochemistry
The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalome... more The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalomethyl[carboxyethyl] ketones [R(3)C(O)CHC(R(1))OMe, where R(3)=CF(3), CCl(3), CO(2)Et and R(1)=Me, Et, Pr, Bu, i-Pent, CH(2)CH(2)CO(2)Me] with propargyl amines [R(2)NHCH(2)CCH, where R(2)=Pr, PhCH(2)] is reported. Yields, solvents and reaction times needed for reaction completion, by microwave irradiation (MW), conventional thermal heating (TH) and under ultrasound irradiation (US) are compared. The best results were obtained under US irradiation in good to excellent yields (70-93%).
The Open Crystallography Journal, 2010
... Simone S. Amaral, Patrick T. Campos, Josiane M. dos Santos, Liana da S. Fernandes, Marcos AP ... more ... Simone S. Amaral, Patrick T. Campos, Josiane M. dos Santos, Liana da S. Fernandes, Marcos AP Martins, Helio G. Bonacorso and Nilo Zanatta* ... It is important to notice however, that although the ex-perimental data indicates the existence of electronic reso-nance between the ...
Acta crystallographica. Section E, Structure reports online, 2014
In the crystal structure of the title compound, C28H23F3N4S·CHCl3, the chloro-form solvate mol-ec... more In the crystal structure of the title compound, C28H23F3N4S·CHCl3, the chloro-form solvate mol-ecules connect the pyrimidine mol-ecules into chains along [101] through weak C-H⋯N and C-H⋯Cl hydrogen-bond inter-actions. There are further connections between adjacent chains through F⋯Cl halogen contacts of 3.185 (3) Å, with the -CF3 group presenting a significant short F⋯F inter-chain distance of 2.712 (4) Å. The five-membered pyrazole ring is approximately planar (r.m.s. deviation = 0.050 Å). The pyrimidine ring makes dihedral angles of 84.15 (8) and 4.56 (8)° with the benzene rings.
Acta Crystallographica Section E Structure Reports Online, 2014
Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.004 Å; R factor = 0.054; wR... more Key indicators: single-crystal X-ray study; T = 293 K; mean (C-C) = 0.004 Å; R factor = 0.054; wR factor = 0.217; data-to-parameter ratio = 28.0.
Ultrasonics Sonochemistry, 2012
The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalome... more The synthesis of 14 novel N-propargylic β-enaminones from the reaction of β-alkoxy vinyltrihalomethyl[carboxyethyl] ketones [R(3)C(O)CHC(R(1))OMe, where R(3)=CF(3), CCl(3), CO(2)Et and R(1)=Me, Et, Pr, Bu, i-Pent, CH(2)CH(2)CO(2)Me] with propargyl amines [R(2)NHCH(2)CCH, where R(2)=Pr, PhCH(2)] is reported. Yields, solvents and reaction times needed for reaction completion, by microwave irradiation (MW), conventional thermal heating (TH) and under ultrasound irradiation (US) are compared. The best results were obtained under US irradiation in good to excellent yields (70-93%).
Synthetic Communications, 2012
Novel 1-aryl-4,4,4-trichloro-1,3-butanediones in good yields (80-97%) were synthesized in one pot... more Novel 1-aryl-4,4,4-trichloro-1,3-butanediones in good yields (80-97%) were synthesized in one pot through acetal acylation with trichloroacetyl chloride followed by acid hydrolysis. Structures of all compounds were elucidated by elemental analysis, mass spectrometry, and 1 H/ 13 C nuclear magnetic resonance (NMR) measurements. The 1 H/ 13 C NMR data showed that trichloromethyl-b-diketones 2a-k in solution are predominantly ketoenol. However, the spectroscopic data from 4,4,4-trichloro-2-methyl-1-phenyl-1,3-butabedione (2l) with methyl substituent between carbonyls showed a bias toward the diketo form in solution. X-ray diffraction of monocrystals from 2g and 2i showed that these compounds are cis-ketoenol tautomers.
Journal of Molecular Structure, 2009
The structure of 7-trichloromethyl-2-methylpyrazolo[1,5-a]pyrimidine (1) and 3-bromo-2-methyl-7-(... more The structure of 7-trichloromethyl-2-methylpyrazolo[1,5-a]pyrimidine (1) and 3-bromo-2-methyl-7-(thien-2-yl)pyrazolo[1,5-a]pyrimidine (2) was determined by X-ray diffractometry. The crystal packing for compounds 1 and 2 was discussed in terms of inter-and intramolecular interactions. Compound 1 showed the intramolecular interaction of pyrazole nitrogen and trichloromethyl chlorine (NÁ Á ÁCl), the intermolecular interactions of pyrimidine nitrogen and chlorine (NÁ Á ÁCl) and p-p interaction between pyrazole ring-centroid. Compound 2 showed the intramolecular interaction of nitrogen of pyrazole and thienyl sulfur (NÁ Á ÁS), the intermolecular interactions of nitrogen of pyrimidine and thienyl sulfur (NÁ Á ÁS) and p-p interaction between pyrimidine and pyrazole ring-centroid. Selected crystallographic data are compared with corresponding semi-empirical AM1 data.
Journal of Molecular Structure, 2010
The crystalline structure of four enaminones [R 1 C(O)CH@C(Me)NR 2 R 3 , where R 1 = CCl 3 , R 2 ... more The crystalline structure of four enaminones [R 1 C(O)CH@C(Me)NR 2 R 3 , where R 1 = CCl 3 , R 2 = H, R 3 = Bn (1); R 1 = CHCl 2 , R 2 = H, R 3 = Bn (2); R 1 = CCl 3 , R 2 , R 3 = A(CH 2 ) 4 A (3); R 1 = CHCl 2 , R 2 , R 3 = A(CH 2 ) 2 AOA(CH 2 ) 2 A (4)] were determined by X-ray diffraction. It was found that compounds 1-4 adopted the enaminone tautomeric form. Compounds 1 and 2 displayed intramolecular hydrogen bonds (2.658 6 d (NÁ Á ÁO) P 2.726), which are associated with the presence of resonance-assisted hydrogen bonds (RABHs). The bond length data implicated that p-delocalization in 3 and 4 was reduced in comparison to 1 and 2 and this can be interpreted as some gain of the aromatic character in the chelate form. In addition, it was shown that the crystal packing of these enaminones is governed by CAHÁ Á ÁO, CAHÁ Á ÁCl, ClÁ Á ÁCl weak interactions and these interactions presents interatomic distances in accordance with the reported van der Waals radii of the atoms involved. The energy of these intermolecular interactions was calculated as a difference in energy between the complex on the one hand and the sum of isolated monomers on the other. The energetic contributions of each interaction to the stability of the crystalline packing were determined, firstly for each interaction independently and secondly, for all interactions simultaneously. The additive effect was verified by the fact that the sum of all individual energetic contributions resulted in the same stability as that found when the energetic contribution of all interactions was calculated simultaneously.
Journal of Molecular Structure, 2006
Crystal structure of 4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid benzyl... more Crystal structure of 4-(2-methoxycarbonyl-ethyl)-3,5-dimethyl-1H-pyrrole-2-carboxylic acid benzyl ester has been solved by X-ray diffraction. The crystals are triclinic, space group P 1, with aZ5.4435(18) Å , bZ12.248(2) Å , cZ13.6769(15) Å , aZ70.274(12)8, bZ81.630(15)8, gZ 77.60(2)8, ZZ2 and RZ0.0519. The molecules are strongly linked in dimers by hydrogen bonds, forming rings with R 2 2 ð10Þ as the graph descriptor. The pyrrolic ring, slightly distorted from the C 2v symmetry, is almost planar. This plane makes an angle of 75.5(1)8 with the L.S. plane containing the methoxy-carbonyl group and an angle of 13.6(1)8 with the L.S. plane containing the benzyl group. The internal cohesion of the crystal is supported by three C-H.p intermolecular interactions, with H.Cg (ring centroid) distances ranging from 3.060 to 3.377 Å . Several calculations were performed for the dimer such as density functional theory with a hybrid functional B3LYP, semi-empirical self-consistent field (AM1 and PM3) and self-consistent field molecular orbital Hartree-Fock (SCF-MO HF) method. The latter calculation was repeated for the isolated molecule. In all cases the minimum of the energy is achieved with the substituents assuming a more perpendicular position to the central aromatic ring than is experimentally observed. q
Journal of Molecular Structure, 2010
The structure of three 1-cyanoacetyl-3-alkyl[aryl]-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyr... more The structure of three 1-cyanoacetyl-3-alkyl[aryl]-5-trifluoromethyl-5-hydroxy-4,5-dihydro-1H-pyrazoles (1-3) has been determined by X-ray diffractometry. The 4,5-dihydro-1H-pyrazole rings were obtained as almost planar structures showing RMS deviation at a range of 0.0196-0.0736 Å. The data demonstrate that the molecular packing is dependent on the substituent present in each molecule. In addition, a computational investigation using semi-empirical AM1 and RM1 methods was performed in order to investigate the correlation between experimental and calculated geometrical parameters. The data obtained suggest that the structural data furnished by the AM1 method is in better agreement with those experimentally determined for the above compounds. An analysis of the p-electron delocalization by HOMA calculations indicate that there is a hyperconjugation effect in the imine group toward to phenyl group at ring 3-position of compound 2, and that this resonance effect decrease in compounds 1 and 3. In addition, it was showed that bond N(1) and C(6) do not have an amide character. Thus, the O(6)-C(6)-N(1)-N(2)-C(3) fragment is not completely delocalized mainly due to the low p-electron delocalization in N(1)-N(2) bond for all compounds.
Journal of Molecular Structure, 2011
Abstract The X-ray diffraction data determined for eight 3-(R 3), 4-(R 4), 4, 4-(R 4/R 4'... more Abstract The X-ray diffraction data determined for eight 3-(R 3), 4-(R 4), 4, 4-(R 4/R 4') and/or 5-(R 5) 5-hydroxy-4, 5-dihydroisoxazoles [where R 3= Ph, R 4/R 4'= H/H, R 5= CCl 3 (1); R 3= 4-Br-C 6 H 4, R 4/R 4'= H/H, R 5= CCl 3 (2); R 3= thien-2-yl, R 4/R 4'= H/H, R 5= CCl 3 ( ...
Journal of Molecular Structure, 2011
The crystalline structure of five 3-(R3) and/or 5-(R5)-substituted 7-trichloromethyl-2-methylpyra... more The crystalline structure of five 3-(R3) and/or 5-(R5)-substituted 7-trichloromethyl-2-methylpyrazolo [1, 5-a] pyrimidines [where R3, R5= H, Pr (1); Br, H (2); Br, Me (3); H, H (4); and H, Me (5)] were studied from X-ray diffractometry data. It was found that compounds ...
Journal of Heterocyclic Chemistry, 2010
Six pyrazolo[1,5-a]pyrimidines bearing a 7-trifluoromethyl (three compounds), a 7-trichloromethyl... more Six pyrazolo[1,5-a]pyrimidines bearing a 7-trifluoromethyl (three compounds), a 7-trichloromethyl (two compounds), and a 7-ethoxycarbonyl (one compound) have been structurally characterized. The new X-ray structures of 2-methyl-5-(p-bromophenyl)-7-trifluoromethylpyrazolo[1,5-a]pyrimidine (3) and 2-methyl-7-trichloromethylpyrazolo[1,5-a]pyrimidine (4) are reported. The combined use of GIAO/ B3LYP/6-311þþG(d,p) calculations with NMR spectroscopy in solution and in the solid state allows to establish some general rules that can be useful for characterizing related compounds. Compounds 3 and 4 present in the solid-state interesting intra-and intermolecular halogen bonds.
Journal of Chemical Crystallography, 2012
The trichloroacetoamidoxime was synthesized following the principles of green chemistry in excell... more The trichloroacetoamidoxime was synthesized following the principles of green chemistry in excellent yield (90 %). This compound crystallizes in the orthorhombic system with space group P2 1 2 1 2 1 and the cell parameters are a = 5.7353 (3), b = 10.5167 (8) Å , c = 21.4787 (16) Å , a, b and c = 90°, V = 1295.52 (15) Å 3 , Z = 4. The final residual factor is R 1 = 0.0429, wR 2 = 0.0884. The presence of the intermolecular hydrogen bonds generates pseudo rings of five members between two molecules that indicate the amido oxime conformation for trichloroacetoamidoxime.
Arkivoc, 2009
... Preparation of trichloroacetoamidoxime in aqueous media and application in one pot synthesis ... more ... Preparation of trichloroacetoamidoxime in aqueous media and application in one pot synthesis of 1,2,4-oxadiazoles Lizandra C. Bretanha, a Dalila Venzke, a Patrick T. Campos, b Anaí Duarte, a Marcos AP Martins, b Geonir M. Siqueira, a * and Rogério A. Freitag a * ...