Publicação 11

“Chemical Transformations of Mono- and Bis(buta-1,3-dien-1-yl)porphyrins: A New Synthetic Approach to Mono- and Dibenzoporphyrins”

Silva, A. M. G. ; de Oliveira, K. T. ; Faustino, M. A. F. ; Neves, M. G. P. M. S ; Tome, A. C. ; Silva, A. M. S. ; Cavaleiro, J. A. S. ; Brandão, P. ; Felix, V. .
Eur J Org Chem 2008, 704-712.

Doi 10.1002/ejoc.200700852


β-Butadienyl- and β,β′-dibutadienylporphyrins were prepared by the Wittig reaction of β-formyl- and β,β′-diformyl-meso-tetraphenylporphyrins with allylic phosphorus ylide. Subsequent treatment of β-butadienylporphyrin with dienophiles afforded the corresponding Diels–Alder adducts. In the absence of dienophiles, β-butadienylporphyrin underwent electrocyclization, followed by oxidation, to give monobenzoporphyrin in good yield. Similarly, adjacent and opposite dibenzoporphyrins were successfully synthesized from adjacent and opposite β,β′-dibutadienylporphyrins, respectively. This is the first report of electrocyclization of β-butadienylporphyrins. The structures of mono- and dibenzoporphyrin nickel complexes, as well as of a Diels–Alder adduct, were determined by single-crystal X-ray diffraction; a strong distortion from the planarity of the porphyrin core was observed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

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 Publicação 10

“Luminescent Langmuir–Blodgett film of a new amphiphilic Eu3+ ß-diketonate”

Gomes, L. F. ; de Oliveira, K. T. ; Neri, C. R. ; Sousa Filho, P. C. ; Del Bianco, M. J. ; Ramos, A. P. ; Zaniquelli M. E. D. ; Serra, O. A.
J Lumin. 2008, 128, 1339-1347.

Doi 10.1016/j.jlumin.2008.01.002


This work reports on the synthesis and characterization of the ligand 3-hexadecylpentane-2,4-dione (Hhdacac) and its Eu3+ complexes Eu(hdacac)6·2H2O, Eu(hdacac)6·phen and Eu(hdacac)6·tta, where phen and tta denote 1,10-phenanthroline and thenoyltrifluoroacetone, respectively. These new compounds present long carbon chains and their expected miscibility into non-polar ambients is confirmed by the emission spectra of Eu(hdacac)6·tta in hexane. Moreover, the amphiphilic properties of Eu(hdacac)6complexes allow the obtainment of thin luminescent films by the Langmuir–Blodgett technique. In both cases (solids and films), the typical antenna effect of β-diketonates is observed. The alluring characteristics of these compounds raise great interest in many fields of Materials Science, like photo- and electro-luminescent materials (mainly thin “organic” films), metal catalysts or probes in non-polar solutions, and Langmuir–Blodgett films of several compositions. For the characterization of these products, nuclear magnetic resonance spectroscopy (1H NMR), thermogravimetric analysis, elementary analyses (C, H), scanning electron microscopy (energy dispersive X-ray spectroscopy), absorption (UV–vis/FT–IR) and photoluminescence spectroscopies were used. 

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 Publicação 9

“Detailed ¹H and ¹³C NMR structural assignment and relative stereochemistry determination for three closely related sesquiterpene lactones”

Heleno, V. C. G. ; de Oliveira, K. T. ; Lopes, J. L. C. ; Lopes, N. P. ; Ferreira, A. G. .
Magn. Reson. Chem. 2008, 46, 576-581.

Doi 10.1002/mrc.2220


A complete analysis of 1H and 13C NMR spectra of the trypanocidal sesquiterpene lactone eremantholide C and two of its analogues is described. These structurally similar sesquiterpene lactones were submitted to 1H NMR, 13C {1H} NMR, gCOSY, gHSQC, gHMBC, J-resolved and DPFGSE-NOE NMR techniques. The detailed analysis of those results, correlated to some computational calculations (molecular mechanics), led to the total and unequivocal assignment of all 1H and 13C NMR data. The determination of all 1H/1H coupling constants and all signal multiplicities, together with the elimination of previous ambiguities were also achieved. Copyright © 2008 John Wiley & Sons, Ltd.

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 Publicação 8

“Synthesis of new amphiphilic chlorin derivatives from protoporphyrin-IX dimethyl ester”

de Oliveira, K. T. ; Silva, A. M. S. ; Tome, A. C. ; Neves, M. G. P. M. S ; Neri, C. R. ; Garcia, V. S. ; Serra, O. A. ; Iamamoto, Y. ; Cavaleiro, J. A. S. .
Tetrahedron. 2008, 64, 8709-8715.

Doi 10.1016/j.tet.2008.06.103


A simple synthesis of new amphiphilic chlorin derivatives from protoporphyrin-IX dimethyl ester is reported. The preparation of such compounds is based in a straightforward methodology, which involves the Diels–Alder reaction of protoporphyrin-IX dimethyl ester with maleic anhydride followed by addition of nucleophilic species to the initially formed cycloadducts, a transformation, which is highly regioselective. Preliminary photophysical studies with the new compounds show that they meet adequate features for PDT applications.

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Publicação 7

“Synthesis of homoallylic oxygenated a-methylene-?-butyrolactones: a model for preparing biologically active natural lactones”

Sass, D. C. ; de Oliveira, K. T. ; Constantino, Mauricio G. .
Tetrahedron. Lett. 2008, 49, 5770-5772.

Doi 10.1016/j.tetlet.2008.07.099


In this Letter we describe a 12% overall yield synthesis of a model for homoallylic oxygenated α-methylene-γ-butyrolactones with relative stereochemistry defined by selective hydrogenation with Rh/Al2O3. The synthesis was realized in 9 steps involving simple reactions.

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 Publicação 6

Reactivity in Diels-Alder reactions: a computational experiment.

Lacerda Júnior, V. ; de Oliveira, K. T. ; Silva, R. C. ; Constantino, M. G. ; da Silva, G. V. J..Quim Nova, 2007, 30, 727-730.

Doi S0100-40422007000300038


A computational quantum chemistry experiment is described of Diels-Alder reactions between 2-cycloenones and cyclopentadiene. The effects of FMO-Frontier Molecular Orbitals (HOMO-LUMO) and of the withdrawing nature of substituents at the C=C bond of cycloenones were evaluated. The calculations were made using HF/STO-3G and B3LYP/6-31+G(d,p) methods. The FMO based indexes are in agreement with the experimentally observed reactivity order. NBO – Natural Bond Orbitals – analysis was used to ascertain the effect of C=C substituents on the dienophile reactivity.

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Publicação 5

Aromaticity and Homoaromaticity in Methano[10]annulenes.

Caramori, G. F. ; de Oliveira, K. T. ; Galembeck, S. E. ; Bultinck, P. ; Constantino, M. G..
J Org. Chem. 2007, 72, 76-85.

Doi 10.1021/jo061702v


Aromaticity and neutral homoaromaticity have been evaluated in methano[10]annulenes systems, 1,4-methano[10]annulene (1), 1,5-methano[10]annulene (2), and 1,6-methano[10]annulene (3). C−C bond lengths indicate that 1 presents higher bond alternation than 2 and 3. The relative energies were determined at the B3LYP/6-311+G(d,p) level, and they pointed out that 3 is the most stable isomer. Strain energies, evaluated employing homodesmotic reactions, show the same order as the relative energies. Through a decomposition of strain energies, it could be concluded that the rings absorb more tension than the bridges. The changes in aromaticity were evaluated by magnetic susceptibilities, χM, HOMA, NICS, and resonance energies, RE. HOMA, RE, and χM indicate that 2 and 3 are strongly, and 1 is fairly, aromatic. NICS does not provide reliable results, due to interference of ring and bridge atoms. NBO analysis presents some interactions that suggest the existence of neutral homoaromaticity. GPA indices (evaluated at the B3LYP/6-31G* level) point out that homoaromaticity plays a relevant role only in 3. Moreover, this work is the first in the current literature that studies 1,4-methano[10]annulene (1).

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Publicação 4

.Analysis of a cycloheptenone derivative: An experimental and theoretical approach

de Oliveira, K. T. ; Lacerda Júnior, V. ; Constantino, M. G. ; Donate, P. M. ; da SILVA, G. V. J. ; Brocksom, T. J. ; Frederico, D..
Spectrochim. Acta. Part A, Molecular Spectroscopy, 2006, 63, 3, 709-713.

Doi 10.1016/j.saa.2005.06.023


A detailed analysis with total assignment of 1H and 13C NMR spectral data for a cycloheptenone derivative, a key intermediate for the synthesis of perhydroazulene terpenoids, is related. These assignments are based on 1D 1H and 13C NMR and on 2D NMR techniques including gCOSY, gHSQC, gHMBC, J-resolved and NOEDIF experiments. The unequivocal assignments were supported by theoretical chemical shifts and scalar coupling constant calculations at GIAO B3LYP/cc-pVDZ level from optimized structures at the same level of theory.

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Publicação 3

Core Structure of Eremophilanes and Bakkanes through Niobium Catalyzed Diels-Alder Reaction: Synthesis of (±)-Bakkenolide A.

Constantino, M. G. ; de Oliveira, K. T. ; Pollo, E. C. ; da Silva, G. V. J. ; Brocksom, T. J.
J Org. Chem. 2006, 71, 9880-9883.

Doi 10.1021/jo061722x


A suitable intermediate for the synthesis of eremophilanes and bakkanes was prepared by a highly regioselective and stereoselective one-step synthesis through a niobium catalyzed Diels−Alder reaction. As a demonstration of the versatility of this intermediate, a total synthesis of (±)-bakkenolide A is described.

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Publicação 2

A synthetic approach to bicyclo[6.2.1]undecane ring systems.

Constantino, M. G. ; de OLIVEIRA, K. T. ; Beatriz, A. ; da Silva, G. V. J..
Tetrahedron. Lett. 2003, 44, 13, 2641-2643.

Doi 10.1016/S0040-4039(03)00377-0


A synthesis of a functionalized bicyclo[6.2.1]undecane, N-(7-hydroxymethyl-bicyclo[6.2.1]undeca-3,5,9-trien-2-yl)-4-methyl-benzenesulfonamide, is described. Starting with a [6+4] cycloaddition between cyclopentadiene and cycloheptatrienone, the final product was prepared in five steps with an overall 37% yield. The remarkable resistance to hydrolysis of an intermediate lactam was overcome by tosylating the amide and reducing with LiAlH4.

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Publicação 1

Analysis of the ¹H and ¹³C NMR spectra of bicyclo[6.2.1]undecane ring systems .

Constantino, M. G. ; de Oliveira, K. T. ; Beatriz, A. ; da Silva, G. V. J..
Magn. Reson. Chem. Inglaterra 2003, 41, 9, 726-728.

Doi 10.1002/mrc.1233


A detailed NMR analysis with full assignment of the 1H and 13C spectral data for two polycyclic compounds is described. These compounds are derivatives of the product obtained from the pericyclic reaction between cyclopentadiene and tropone. Peculiar intriguing conformational features of these molecules are discussed. Copyright © 2003 John Wiley & Sons, Ltd.

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