Chemical investigation of aerial parts of Schkuhria pinnata var wislizeni (Asteraceae) allowed the characterization of the sesquiterpene lactones 1, 2 and 5, the flavonoids 3 and 4, and the acyl phenyl propanoids 10 and 11. Structure 2, named dischkuhriolin, was confirmed as a Diels Alder adduct of 1 as dienophile and a guaianolide as diene. Spectroscopic analysis of 5 and its diacetyl derivative allowed the structural correction of compounds previously reported from Schkuhria. 2, 10 and 11 are new natural compounds. Biological assays indicated that the mixture 10 + 11 showed antioxidant activity expressed as inhibition of AAPH-induced damage in rat pancreatic homogenate.

La investigación química de las partes aéreas de Schkuhria pinnata var wislizeni (Asteraceae) permitió la caracterización de las lactonas sesquiterpénicas 1, 2 y 5, los favonoides 3 y 4, y los acil fenil propanoides 10 y 11. La estructura 2, nombrada como dieschkuhriolina, fue confirmada como un aducto de Diels Alder de 1 como dienófilo y una guayanólida como dieno. El análisis epectroscópico de 5 permitió la corrección estructural de compuestos reportados previamente de Schkuhria. 2, 10 y 11 son nuevos compuestos naturales. Los ensayos biológicos indicaron que la mezcla 10 + 11 mostró actividad antioxidante expresada como inhibición del daño inducido por HAAP en homogenado pancreático de rata.

The preparation and structural characterization of dimeric and monomeric siloxanes are described. The silicon complexes were obtained from β-amino alcohols and dichlorodimethylsilane, bisdimethylaminodimethylsilane and diphenyldichlorosilane. The complexes were characterized by ¹H, 13C and 29Si NMR spectroscopy and mass spectrometry. The X-ray crystallography study for one compound confirmed the formation of a sixteen-membered heterocycle.

En este trabajo se describe la preparación y la caracterización de siloxanos diméricos y monoméricos. Los complejos de silicio se obtuvieron por reacción de β-amino alcoholes con diclorodimetilsilano, bisdimetilaminodimetilsilano y diclorodifenilsilano. Los complejos se caracterizaron por RMN de ¹H, 13C y 29Si, y espectrometría de masas. La estructura molecular de un anillo de 16 miembros para uno de los compuestos se confirmó por difracción de rayos-X.

Neste trabalho foram estudados os efeitos eletrônicos induzidos por p-substituintes no anel fenilico de diversos compostos carbonílicos conjugados [4-p-R-fenil-1-(1,3-ditiolano-2-ilideno)-3 E-buteno-2-ona, onde R=NO2, Cl, Br, OMe, NEt2 (2-6)], e sua reatividade frente a Fe2(CO)9 usando o diagrama de Hammett. A estrutura dos compostos (3 e 4b) foi totalmente estabelecida por análise de difração de raio-X.

The electronic effects induced by p-substituents on the phenyl ring of several novel cross-conjugated carbonyl compounds [4-p-R-phenyl-1-(1,3-dithiolane-2-ylidene)-3 E-butene-2-one, where R= NO2, Cl, Br, OMe, NEt2 (2-6),] and their reactivity towards Fe2(CO)9 have been studied using a Hammett plot. The structure of two compounds (3 and 4b) was fully established by X-ray diffraction analysis.

Neste trabalho foram estudados os efeitos eletrônicos induzidos por p-substituintes no anel fenilico de diversos compostos carbonílicos conjugados [4-/>-R-fenil-1-(1,3-ditiolano-2-ilideno)-3E-buteno-2-ona, onde R=NO2, Cl, Br, OMe, NEt2 (2-6)], e sua reatividade frente a Fe2(CO)9 usando o diagrama de Hammett. А estrutura dos compostos (3 e 4b) foi totalmente estabelecida poranálise de difração de raio-X.

The electronic effects induced by p-substituents on the phenyl ring of several novel cross-conjugated carbonyl compounds [4-p-R-phenyl-1-(1,3-dithiolane-2-ylidene)-3E-butene-2-one, where R= NO2, Cl, Br, OMe, NEt2 (2-6),] and their reactivity towards Fe2(CO)9 have been studied using a Hammett plot. The structure of two compounds (3 and 4b) was fully established by X-ray diffraction analysis.

The molecular and crystal structure of Pentolame, a 17β-aminoestrogen (17β-(5'-hydroxy-1'-pentylamino)-1,3,5(10)-estratrien-3-ol), has been determined by single crystal X-ray diffraction as its monohydrate. The structure was used to determine the absolute configuration of the newly formed stereogenic centre (C17), which could not be established unambiguously by NMR spectroscopy. This study confirms the absolute configuration as 17S by internal reference with the starting material, estrone [(8R,9S,13S,14S)-3-Hydroxyestra-1,3,5(10)-trien-17-one]. Pentolame monohydrate crystallizes in the triclinic system, space group P 1 with Z = 1. The B ring adopts the typical conformation of a distorted 7α,8β-half-chair. In crystal packing, the water molecule plays an essential role joining adjacent infinite chains, made up by head to tail hydrogen bonded steroid molecules.

En este trabajo se determinó por difracción de rayos X, la estructura molecular y cristalina del 17β-aminoestrógeno Pentolame. Su estructura se investigó a fin de determinar sin ambigüedades la configuración absoluta del nuevo centro estereogénico (C17) formado durante su obtención. Los resultados obtenidos mediante referencia interna al material de partida, estrona [(8R,9S,13S,14S)-3-Hidroxiestra-1,3,5(10)-trien-17-ona], confirman la asignación 17S hecha en base a los datos de espectroscopía de Resonancia Magnética Nuclear. El monohidrato de pentolame cristaliza en el sistema triclínico, en el grupo espacial P 1 con una molécula por celda. El anillo B de la molécula, adopta la conformación típica 7α,8β de media silla observada en este tipo de esteroides. En el empacado cristalino la molécula de agua desempeña un papel esencial uniendo cadenas infinitas adyacentes, formadas por interacciones de puente de hidrógeno entre la "cabeza" y la "cola" de dos moléculas del esteroide.

Dois novos casos de heptacoordenação em complexos organoestânicos(IV) são descritos. Ambos possuem geometria pentagonal bipiramidal e mostram os grupos orgânicos nas posições axiais, com os ligantes formando cinco ligações no plano equatorial com os átomos de estanho(IV). O primeiro complexo [nBu2Sn(H2daptsc)]Cl2 •MeNO2 (1) é totalmente novo, ao passo que o segundo, [Me2Sn(H2dapsc)][Me2 SnCl4] (2), embora anteriormente descrito na literatura, somente agora teve a sua estrutura determinada. Tanto em 1 quanto em 2 as espécies heptacoordenadas são catiônicas; ao passo que em 1 o contra-íon é um simples Cl-, em 2 é um ânion complexo, isto é [Me2SnCl4]2-.

Two new cases of heptacoordination in organotin(IV) complexes are described. Both possess pentagonal bipyramidal geometry and show the organic groups on the axial positions, with the ligands forming five bonds to tin(IV) on the equatorial plane. The first complex, [nBu2Sn(H2daptsc)]Cl2 •MeNO2 (1) is entirely new, whereas the second, [Me2Sn(H2dapsc)][Me2 SnCl4] (2), although previously reported, only now had its structure determined. In both 1 and 2 the heptacoordinate species are cationic, but whereas in 1 the counterion is simply Cl-, in 2 it is a complex anion, namely [Me2SnCl4]².

2-benzoylpyridine N4-p-methoxyphenylthiosemicarbazone, HBz4pMeOPh, crystallizes with a Z arrangement of N1 and N2 with respect to C7-N2, which allows for the N3-H3A...N1 hydrogen bond and a six-membered ring. In addition, a 5-membered ring involving a second hydrogen bond, N4-H4A...N2 results in the N2 and S1 E conformation with respect to N3-C8. Intramolecular C-H...O and C-H...S hydrogen bonds create supramolecular chains.

La 2-benzoilpiridina N4-p-metoxifeniltiosemicarbazona, HBz4pMeOPh, cristaliza con un arreglo Z de N1 y N2 con respecto a C7-N2 lo que permite la formación del enlace de hidrógeno N3-H3A...N1 en un anillo de seis miembros. Adicionalmente se forma un anillo de 5 miembros el cual involucra un segundo enlace de hidrógeno, N4-H4A...N2 del cual resulta una conformación E de N2 y S1 con respecto a N3-C8. Se producen cadenas supramoleculares debido a los enlaces de hidrógeno C-H...O y C-H...S.