Edison P. Wendler

Identification of defensive compounds in metathoracic glands of adults of the stink bug Dichelops melacanthus (Hemiptera: Pentatomidae)

Os conteudos das glândulas metatoracicas de insetos adultos do percevejo Dichelops melacanthus (Hemiptera: Pentatomidae) foram analisados. Os compostos de defesa foram identificados combinando as tecnicas de cromatografia gasosa (CG), cromatografia gasosa acoplada a espectrometria de massas (CG-EM) e por comparacao de seus indices de retencao com os de compostos padroes. Tridecano foi o componente majoritario, seguido de quantidades menores e aproximadamente iguais de (E)-4-oxo-2-hexenal e (E)-2-octenal. Tambem foram identificados (E)-2-hexenal, decano, acetato de (E)-2-hexenila, undecano, (E)-4-oxo-2-octenal, dodecano, acetato de (E)-2-octenila, 1-trideceno, tetradecano e pentadecano. The contents of metathoracic glands of adults of the stink bug Dichelops melacanthus (Hemiptera: Pentatomidae) were analyzed. Compounds were identified by gas chromatography (GC), coupled GC-mass spectrometry and matching retention indices and mass spectra with those of authentic samples. Tridecane was the major component followed by lesser and approximately equal amounts of (E)-4-oxo-2-hexenal and (E)-2-octenal. Other compounds identified include (E)-2-hexenal, decane, (E)-2-hexenyl acetate, undecane, (E)-4-oxo-2-octenal, dodecane, (E)-2-octenyl acetate, 1-tridecene, tetradecane and pentadecane.

Volatile Oil of Psidium cattleianum Sabine from the Brazilian Atlantic Forest

Abstract The essential oil obtained by hydrodistillation of fresh leaves of Psidium cattleianum Sabine, collected in the Atlantic Forest in southeastern Brazil, was analyzed by GC and GC/MS. The oil had the main constituents α-thujene (25.2%), 1,8-cineole (16.4%) and β-caryophyllene (10.2%).

Leaf Essential Oil Compositon of Pimenta pseudocaryophyllus (Gomes) L. R. Landrum Native From Brazil

Abstract Hydrodistillation of fresh leaves of Pimenta pseudocaryophyllus Gomes collected in the Atlantic Forest, south-eastern Brazil, afforded the essential oil in 0.48% yield. The major component was isolated from oil and analyzed by GC, GC/MS and NMR techniques, which revealed the compound chavibetol (70.9%). Others major constituents found were methyl eugenol (20.7%) and o-cymene (2.8%).

Joint use of microwave and glycerol-zinc (II) acetate catalytic system in the synthesis of 2-pyridyl-2-oxazolines

Abstract Glycerol combined with zinc (II) acetate catalyzed the reaction of 2-amino alcohols and 2-cyanopyridines under microwave irradiation, resulting in 2-pyridyl-2-oxazolines. Comparing the conversion to that obtained by conventional heating, a significant decrease in the reaction time was achieved. At the end of the reaction, the product was isolated and the glycerol-zinc (II) acetate catalytic system was recycled four times for the same transformation in reasonable to acceptable yields. The products were obtained in their pure form by simple filtration in a short pad of silica.

Response of Diabrotica speciosa (Coleoptera: Chrysomelidae) to 1,4-dimethoxybenzene and analogs in common bean crop

Uma serie de compostos, sinteticos e comerciais, analogos ao 1,4-dimetoxibenzeno, um cairomonio de Diabrotica speciosa, juntamente com outros compostos comerciais atrativos para outras especies de Diabrotica, tiveram suas atividades testadas frente a D. speciosa. Armadilhas de copos amarelos contendo os compostos foram instaladas em plantacao de feijao. As avaliacoes foram realizadas 24 horas depois. Armadilhas com 1,4-dimetoxibenzeno capturaram significativamente mais insetos do que armadilhas testemunha. Armadilhas com analogos do 1,4-dimetoxibenzeno nao capturaram mais insetos que as armadilhas testemunha. Os resultados mostraram que a posicao e a natureza dos substituintes, juntamente com a aromaticidade verificada na estrutura do composto natural, sao cruciais para a atratividade.

Crystal and molecular structures of three 2-substituted 4-methyloxan-4-ol derivatives studied by X-ray crystallography and by PM6 calculations

Abstract The conformational features of three 2-substituted 4-methyloxan-4-ol (tetrahydropyran) derivatives were investigated by single crystal X-ray crystallographic studies and the geometries were optimized using semi-empirical PM6 methods. The tetrahydropyran ring in each of (I)–(III) adopts a chair conformation with their hydroxyl groups occupying equatorial, axial and axial positions, respectively. The strongest hydrogen bonding interactions apparent in each of the respective crystal structures, as judged from distance and angle considerations, involve the ring-bound O2-hydroxyl group and tetrahydropyran ring oxygen atom. These hydrogen bonds lead to a supramolecular chain with a linear topology in each case but generated by glide symmetry in (I) and (II), and 21-screw symmetry in (III). In the latter, a two dimensional array constructed by O—H…O bonding is found leading to undulating layers. Despite the absence of additional O—H…O hydrogen bonding sites, two dimensional arrays are also generated in each of (I) and (II), but this time mediated by C—H…O contacts that lead to flat layers. The theoretical structures for each of (I) and (III) differ from their respective experimental structures in terms of the relative orientation of the aromatic substituent. By contrast, for (II), there is close agreement between the experimental and theoretical structures. (I) C12H16O2, monoclinic, Cc, a = 18.7887(8), b = 6.0634(2), c = 10.4178(4) Å, β = 116.945(7)°, V = 1057.99(10) Å3, Z = 4, R1 = 0.029; (II) C13H18O3, orthorhombic Pc21n, a = 9.3664(17), b = 10.0472(18), c = 12.240(2) Å, V = 1151.9(3) Å3, Z = 4, R1 = 0.037; (III) C13H18O4, orthorhombic P212121, a = 9.814(3), b = 9.966(2), c = 11.845(2) Å; V = 1158.5(5) Å3, Z = 4, R1 = 0.079.