Rhodium catalyzed hydroformylation of kaurane derivatives: A route to new diterpenes with potential bioactivity

Kaurenic and grandiflorenic acids are naturally occurring diterpenes whose biological activity has been described. Both acids contain an exocyclic methylenic double bond that allows further functionalization on their structure. In an attempt to expand the number of derivatives of these two natural products, we have undertaken a study on the hydroformylation of the methyl esters of the two acids and the trimethylsilyl ether of kaurenol. These substrates have been hydroformylated by using unmodified Rh catalysts, as well as Rh/PPh3 and Rh/tris-(o-t-butylphenyl)phosphite catalytic systems at 100 °C and 20 bar of CO/H2 (1:1). For the three substrates, the two Rh catalysts modified with P-donor ligands, produced high conversions and chemo- and regioselectivities in the diastereoisomeric pair of linear aldehydes. In all cases, the stereoselectivity observed is strongly dependent of the system used, being the most diastereoselective the least hindered unmodified Rh/CO catalyst. A correlation between the higher diastereoselectivity and the faster [beta]-elimination of the metal-alkyl intermediate observed in the unmodified system is discussed.http://www.sciencedirect.com/science/article/B6TF5-4RVMXFD-3/1/d27e671ad9e0b7fc325dfd0bdf413c7

Información Investigador: Fonseca Velázquez, Yuraima Josefina

Resumen Curricular Licenciada Yuraima Fonseca, egresada de la Facultad de Ciencias de la Universidad de Los Andes, ha trabajado como investigadora contratada para el CONYCIT y en Investigación y Desarrollo en la empresa Glassven, ha participado varias veces en Congresos Nacionales de Química y actualmente se encuentra culminando la maestría en la Facultad de Ciencias, Postgrado Interdisciplinario en Química Aplicada PIQA mención :Estudio de Materiales.UniversitarioSíntesis y caracterización de complejos acuosolubles de rutenio, rodio y molibdeno en la hidroformilación e hidrogenación de naftas y productos naturales.Marzo de 2007Licenciada en Química+58 274 2401380Facultad de [email protected]

Hidrogenación catalítica de los ésteres metílicos de los ácidos kaurénico y grandiflorénico con RuCl2(DMSO)4 en medio homogéneo y bifásico.

RuCl2(DMSO)4 was used in hydrogenation reactions of kaurenoic and grandifl orenic acid methyl ester in homogeneous medium and grandifl orenic acid methyl ester in biphasic toluene/water media. The reaction products were characterized by GC-MS. The catalytic parameters were optimized giving high percent conversion and some stereomeric preference for both acids.13 - [email protected]@[email protected]@ula.veSemestralRuCl2(DMSO)4 fue utilizado en reacciones de hidrogenación de los ésteres metílicos de los ácidos kaurenoico y grandifl orénico en medio homogéneo y el éster metílico del ácido grandifl orénico en medio bifásico tolueno/agua. Los productos de reacción fueron caracterizados por cromatografía de gases acoplado a un espectrómetro de masas (CG-EM). Se optimizaron los parámetros catalíticos obteniéndose altos porcentajes de conversión con preferencia estereomérica para ambos ácidos

Synthesis, characterization and Hydroformylation Catalytic Activity of 1-hexene of Water-soluble RuCl2(DMSO)2(PySO3Na)2 Complex

En el presente trabajo describimos la síntesis y caracterización del nuevo complejo acuosoluble [Ru(Cl)2(DMSO)2(PySO3Na)2] donde [PySO3Na] es el ligando piridina p-sulfonato de sodio. Este complejo fue sintetizado por adición lenta del ligando a una solución metanólica del complejo cis-[Ru(Cl)2(DMSO)4] bajo reflujo y atmósfera inerte. Este nuevo complejo fue caracterizado utilizando las técnicas de FT-IR y RMNH1. El nuevo complejo mostró ser activo en la reacción catalitica de hidroformilación de 1-hexeno, sin embargo, no resultó ser muy activo en una prueba preliminar de hidroformilación catalítica con nafta real en medio bifásico. También se llevó a cabo la optimización de parámetros como tiempo, temperatura, presión y relación sustrato/catalizador usando 1-hexeno como sustrato. El sistema mostró pérdida de actividad durante las pruebas de reuso del catalizador, sin embargo mostró actividad en presencia de tiofeno y de mercurio metá[email protected] this work we describe the synthesis and characterization of a new water soluble ruthenium complex [Ru(Cl)2(DMSO)2(PySO3Na)2] (complex 1); where [PySO3Na] is the sodium salt of p-sulphonated pyridine. Complex 1 was obtained by slow addition of ligand to a cis-[Ru(Cl)2(DMSO)4] complex solution under inert atmosphere, the mixture was refluxed for 1 hour. Complex 1 was characterized by FT-IR and 1H NMR techniques. Complex 1 was active in the catalytic 1-hexene hydroformylation and a preliminary test with real naphtha in a biphasic reaction mixture (water/toluene) shows little activity. Temperature, pressure, and substrate/catalyst ratio were studied with 1-hexene substrate. Catalysis with metallic particles was tested with a mercury drop trial giving negative results. The reuse of the aqueous phase in several reactions under the same experimental conditions showed loss of catalytic activity after the second reuse. Complex 1 is active for hydroformylation reaction of 1-hexene even in the presence of thiophene compounds

Synthesis, characterization and hydroformylation catalytic activity of a water-soluble RhCl(CO)(PySO3Na)2 complex using 1-hexene and real naphtha

In this work, we describe the synthesis and characterization of a new water soluble [RhCl(CO)(PySO3Na)2], complex (1); where [PySO3Na] is the sodium salt of p-sulfonated pyridine ligand. Complex (1) was obtained in methanol, reacting the dried sodium salt of p-sulfonated pyridine ligand with [Rh(Cl)(CO)2]2 complex under inert atmosphere. Complex (1) was characterized by FT-IR and 1H NMR techniques. Complex (1) was active in the catalytic hydroformylation of 1-hexene and real naphtha in a biphasic (water/toluene) system. The effects of reaction time, temperature and syngas pressure were studied with 1-hexene as a substrate. Formation of metallic particles was tested with a mercury drop trial, giving negative results. Reuse of the aqueous phase for several times under the same conditions showed little catalytic activity loss. Complex (1) was active for the hydroformylation reaction of 1-hexene, in the presence of thiophene compounds, showing better performance in comparison with water soluble rhodium [email protected]@ula.ve, [email protected]@[email protected]@[email protected]

Synthesis, characterization, and biphasic ionic liquid media 1-hexene hydrogenation reaction of RuCl2(DMSO)2(NC5H4CO2Na-3)2

RuCl2(DMSO)2(NC5H4CO2Na-3)2 is very soluble in the ionic liquid (IL) 1-n-butyl-3-methylimidazolium tetrafluoroborate, [(BMIM)BF4]. The complex was prepared by reacting RuCl2(DMSO)4 with NC5H4CO2Na-3, sodium nicotinate, in toluene, and was characterized by spectroscopic methods. The complex catalyzes the hydrogenation of 1-hexene (600 psi H2, 100 C) in a two-phase system consisting of cyclohexane/[(BMIM)BF4] with 75% conversion in 24 h and modest substrate isomerization. The complex shows good stability and can be reused several times with little loss in [email protected]@ula.ve, [email protected]@[email protected]@[email protected]

Synthesis, characterization and olefin hydroformylation reactions of mer-[Mo(CO)3(p-C5H4N-CN)3]

Artículo Publicado en Springer Science+Business Media B.V. 2010Mer-[Mo(CO)3(p-C5H4N-CN)3] was prepared by UV-irradiation of a THF solution of Mo(CO)6 and paracyanopyridine under heating. The complex was characterized by FT-IR, MS, 1H and 13C NMR and showed catalytic activity for olefin hydroformylation (1-hexene, cyclohexene and 2,3-dimethyl-2-butene as model olefins; 600 psi synthesis gas (pCO/pH2 = 1); 100 C; 24 h; toluene). An examination of the complex catalyzed hydroformylation of a real naphtha cut (El Palito refinery, Venezuela), under the same conditions, also showed activity in the conversion to oxygenated [email protected]@ula.ve, [email protected]@[email protected]@[email protected]

Rhodium catalyzed hydroformylation of kaurane derivatives: A route to new diterpenes with potential bioactivity

Kaurenic and grandiflorenic acids are naturally occurring diterpenes whose biological activity has been described. Both acids contain an exocyclic methylenic double bond that allows further functionalization on their structure. In an attempt to expand the number of derivatives of these two natural products, we have undertaken a study on the hydroformylation of the methyl esters of the two acids and the trimethylsilyl ether of kaurenol. These substrates have been hydroformylated by using unmodified Rh catalysts, as well as Rh/PPh3 and Rh/tris-(o-t-butylphenyl)phosphite catalytic systems at 100 °C and 20 bar of CO/H2 (1:1). For the three substrates, the two Rh catalysts modified with P-donor ligands, produced high conversions and chemo- and regioselectivities in the diastereoisomeric pair of linear aldehydes. In all cases, the stereoselectivity observed is strongly dependent of the system used, being the most diastereoselective the least hindered unmodified Rh/CO catalyst. A correlation between the higher diastereoselectivity and the faster [beta]-elimination of the metal-alkyl intermediate observed in the unmodified system is discussed.http://www.sciencedirect.com/science/article/B6TF5-4RVMXFD-3/1/d27e671ad9e0b7fc325dfd0bdf413c7

Hydrocarbon synthesis using Iron and Ruthenium/SiO2 with FISCHER-TROPSCH catalysis.

CONTENIDO Editorial.El nóbel de química 2007 y la "química superficial" en Venezuela. Imbert, Freddy E. Artículos Científicos Allylic oxidation of ent-Kaurenic acid, ent-Kaurenic acid Methyl Ester and ent-Kaurenol. Aparicio Z., Rosa L.; Bahsas B., Alí H. y Usubillaga, Alfredo Desarrollo de la tecnología de inmovilización: estabilización/solidificación de desechos peligrosos en Costa Rica.Estudio de caso en lodo de electrodeposición. Romero E., Luís G.; Vargas C., Maricruz y Padilla B., Francisco Hydrocarbon synthesis using Iron and Ruthenium/SiO2 with FISCHER-TROPSCH catalysis. Fonseca, Y. J.; Fontal, Bernardo; Reyes, Marisela del C.; Suárez B., Trino; Bellandi, F.; Contreras, Ricardo Rafael; Cancines, Pedro I.; Loaiza, A. y Briceño, M. Artículo Divulgativo Sistemas de producción agrícola sostenible en Los Andes de Venezuela: agricultura orgánica. López, Roberto A. y Contreras B., Froilán [email protected]@[email protected]@[email protected]@ula.veNivel analíticosemestra

Olefin hydroformylation catalysis with RuCl2(DMSO)4.

CONTENIDO Editorial.Algunos logros de "Avances en Química" a sus dos años de aparición. Lárez Velásquez, Cristóbal Semblanza Olga y Jairo Márquez: hacedores de ciencia. Martínez, Yris J. Artículos Científicos Antioxidant and scavenging activity of skyrin on free radical and some reactive oxygen species. Vargas V., Franklin F.; Rivas, Carlos; Zoltan, Tamara; López, Verónica; Ortega, Jessenia; Izzo, Carla; Pineda, María; Medina, José; Medina, Ernesto y Rosales, Luis Olefin hydroformylation catalysis with RuCl2(DMSO)4. Reyes, Marisela del C.; Parra, Enrique J.; Fonseca, Y. J.; Fontal, Bernardo; Suárez B., Trino; Bellandi, Fernando; Contreras, Ricardo Rafael; Romero C., Isolda; Prado, Lenis and Cancines, Pedro I. Reducción catalítica de NOx con Pt soportado sobre zeolitas MFI modificadas con Cu, Co, Fe, Mn. Briceño, Sarah y Del Castillo P., Héctor L. Avance de Investigación Productos inesperados en la transformación química de derivados de la podofilotoxona a través de la reacción de Takai. Reyes, J. Andrés; López Pérez, José Luis; Santiago, Carolina; Delgado Méndez, Paulino; Bahsas B., Alí H.; Amaro, Juan Manuel y Del Olmo, [email protected]@[email protected]@[email protected]@[email protected] analíticosemestra