RESUMEN
A practical, brief, and diastereoselective synthesis of limonoid CDE fragments from a readily available starting material is described. The key step was the titanocene(III)-promoted cyclization of unsaturated epoxylactones, readily prepared from α-cyclocitral. In this way, we confirm the viability of our procedure for the synthesis of a limonoid model with different functionalization patterns. We also report the antifeedant activity of epoxylactones 18 and 19, which show significant antifeedant activity against Spodoptera littoralis and Spodoptera frugiperda, two insect species with different feeding ecologies.
Asunto(s)
Limoninas/química , Compuestos Organometálicos/química , Animales , Conducta Alimentaria , Larva , Limoninas/síntesis química , Especificidad de la Especie , SpodopteraRESUMEN
Radical couplings of epoxides and nitriles mediated by Cp(2)TiCl provide a diastereoselective route to the synthesis of beta-hydroxyketones. The conditions of this "aldol-like" reaction are mild enough to avoid the dehydration of the beta-hydroxyketone. The scope of the coupling reaction with functionalized and tetrasubstituted epoxides has been studied. The radical character of the coupling reactions is demonstrated.
RESUMEN
A new approach to the synthesis of CDE and BCDE molecular fragments of the limonoids havanensin and azadiradione has been achieved from cyclocitral and drimenal in seven steps in overall yields of 20 and 9%, respectively.
Asunto(s)
Técnicas Químicas Combinatorias , Limoninas/síntesis química , Catálisis , Ciclización , Indicadores y Reactivos , Limoninas/análisis , Estructura Molecular , Resonancia Magnética Nuclear BiomolecularRESUMEN
Se informa de un caso de fetus in fetu intraabdominal y a nivel testicular en un nino de nueve meses, observado en el Hospital Universitario de Puebla U.A.P., que ingreso por gastroenteritis y bronconeumonia, diagnosticado adecuadamente por metodos radiologicos en donde la tomografia jugo un papel importante. El paciente fallecio por una neumonia de celulas gigantes y se presentan los hallazgos anatomopatologicos mas descriptivos. Se revisa la literatura y sus posibles teorias etiopatogenicas, haciendo una diferenciacion con otros tipos de teratoma, postulandose los requisitos para su clasificacion