Some anodic oxidations of α-santonine using different experimental conditions were performed on a... more Some anodic oxidations of α-santonine using different experimental conditions were performed on a Pt electrode in acetonitrile medium. Four main products were obtained: 14-hydroxy-ct-santonine, 4,5-epoxy-a-santonine, 14-acetamide-a-santonine and α-santonic acid. These oxidations were important since there are few methods to oxidize the allylic methyl groups attached to a,/3-unsaturated ketones.
An air-stable phosphinito palladium(ii) complex has been found to be an efficient catalyst in the... more An air-stable phosphinito palladium(ii) complex has been found to be an efficient catalyst in the formation of C–C bonds.
Three new diarylbutane lignans, named 9-acetyl-9&... more Three new diarylbutane lignans, named 9-acetyl-9'-pentadecanoil-dihydroclusin (1), 2,3-demethoxy-secoisolintetralin monoacetate (4) and dihydroclusin monoacetate (5), have been isolated from the resin of Bursera fagaroides, together with two known ones, 2,3-demethoxy-secoisolintetralin diacetate (2) and dihydroclusin diacetate (3). The complete structure assignments were obtained by means of (1)H and (13)C NMR spectra.
From the aerial parts of Salvia tiliaefolia Vahl, the known isosalvipuberulin (1) and two new cle... more From the aerial parts of Salvia tiliaefolia Vahl, the known isosalvipuberulin (1) and two new clerodane diterpenoids, salvifolin and tilifodiolide, were isolated. The structure of salvifolin (5) was deduced from spectral data. The structure of tilifodiolide (2) was established by chemical and spectral means and X-ray diffraction analysis.
We have synthesized, characterized and studied the third-order nonlinear optical properties of tw... more We have synthesized, characterized and studied the third-order nonlinear optical properties of two different nanostructures of polydiacetylene (PDA), PDA nanocrystals and PDA nanovesicles, along with silver nanoparticles-decorated PDA nanovesicles. The second molecular hyperpolarizability γ (−ω; ω, −ω, ω) of the samples has been investigated by antiresonant ring interferometric nonlinear spectroscopic (ARINS) technique using femtosecond mode-locked Ti:sapphire laser in the spectral range of 720-820 nm. The observed spectral dispersion of γ has been explained in the framework of three-essential states model and a correlation between the electronic structure and optical nonlinearity of the samples has been established. The energy of two-photon state, transition dipole moments and linewidth of the transitions have been estimated. We have observed that the nonlinear optical properties of PDA nanocrystals and nanovesicles are different because of the influence of chain coupling effects facilitated by the chain packing geometry of the monomers. On the other hand, our investigation reveals that the spectral dispersion characteristic of γ for silver nanoparticles-coated PDA nanovesicles is qualitatively similar to that observed for the uncoated PDA nanovesicles but bears no resemblance to that observed in silver nanoparticles. The presence of silver nanoparticles increases the γ values of the coated nanovesicles slightly as compared to that of the uncoated nanovesicles, suggesting a definite but weak coupling between the free electrons of the metal nanoparticles and π electrons of the polymer in the composite system. Our comparative studies show that the arrangement of polymer chains in polydiacetylene nanocrystals is more favourable for higher nonlinearity.
La oxidación con reactivos suaves del 1,2 diol de la unidad del azúcar de algunas asclepinas proc... more La oxidación con reactivos suaves del 1,2 diol de la unidad del azúcar de algunas asclepinas procede sin la ruptura oxidativa del enlace C-C del glicol. Sin embargo se observa una posterior migración [1,2] para obtener un producto de contracción de anillo en la parte del azúcar.
The Heck Reaction of Allylic Alcohols Catalyzed by an Air-Stable Phosphinito Complex of Palladium... more The Heck Reaction of Allylic Alcohols Catalyzed by an Air-Stable Phosphinito Complex of Palladium(II).-The regioselective method allows access to functionalized aldehydes, ketones and aromatic allylic alcohols thus opening the way to biologi
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Acta Crystallographica Section C Crystal Structure Communications, 2001
The absolute configuration of the neoclerodane glycoside amarisolide, presented here as the monoh... more The absolute configuration of the neoclerodane glycoside amarisolide, presented here as the monohydrate, C26H36O9·H2O, has been determined by association with the known configuration of the glucose moiety. Its structure was established as 2β-(O-β-d-glucopyranosyl)neocleroda-3,13(16),14-trien-15,16-epoxy-18,19-olide. Extensive hydrogen bonding among the hydroxyl groups of the sugar moiety forms layers which are interconnected by water molecules.
Two new p-cymene ruthenium(II) complexes containing as additional ligands N-methylpiperazine ([(η... more Two new p-cymene ruthenium(II) complexes containing as additional ligands N-methylpiperazine ([(η 6-p-cymene)RuCl 2 (CH 3 NH(CH 2) 4 NH)]PF 6 , complex 1) or vitamin K 3-thiosemicarbazone ([(η 6-p-cymene)RuCl 2 (K 3 tsc)], complex 2) were synthesized starting from [(η 6-p-cymene) 2 RuCl 2 ] 2 and the corresponding ligand. The complexes were characterized by elemental analysis, IR, electronic absorption and NMR spectroscopy. The X-ray crystal structure determination of complex 1 revealed "piano-stool" geometry. The differences in the cytotoxic activity of the two complexes are discussed in terms of the ligand present.
The oxidation with mild reagents of the sugar moiety of some asclepines proceeds without oxidativ... more The oxidation with mild reagents of the sugar moiety of some asclepines proceeds without oxidative cleavage of the glycol C-C bond. Nevertheless, a further (1,2) migration to afford the ring contraction of the sugar moiety is observed. Key word: Asclepia linaria, cardenolides, asclepines, gomphoside, oxidations.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
A montmorillonite clay from the State of Durango, Mexico, was used as catalyst. The clay was acti... more A montmorillonite clay from the State of Durango, Mexico, was used as catalyst. The clay was activated with trifluoromethane sulfonic acid and used to study the condensation of different acetophenones in refluxing benzene to produce triphenylbenzenes, β-methylchalcones and pyrylium salts. This catalytic procedure afforded a new simple one-step method for the synthesis of complex organic molecules through the C-C bonds formation and the counter ion for the pyrylium salt. A proposed mechanism of the isolated compounds is discussed as well as their identification by spectroscopic methods and by comparison with reported data, acquired from the previously synthesized derivatives by other synthetic methods.
Some anodic oxidations of α-santonine using different experimental conditions were performed on a... more Some anodic oxidations of α-santonine using different experimental conditions were performed on a Pt electrode in acetonitrile medium. Four main products were obtained: 14-hydroxy-ct-santonine, 4,5-epoxy-a-santonine, 14-acetamide-a-santonine and α-santonic acid. These oxidations were important since there are few methods to oxidize the allylic methyl groups attached to a,/3-unsaturated ketones.
An air-stable phosphinito palladium(ii) complex has been found to be an efficient catalyst in the... more An air-stable phosphinito palladium(ii) complex has been found to be an efficient catalyst in the formation of C–C bonds.
Three new diarylbutane lignans, named 9-acetyl-9&... more Three new diarylbutane lignans, named 9-acetyl-9'-pentadecanoil-dihydroclusin (1), 2,3-demethoxy-secoisolintetralin monoacetate (4) and dihydroclusin monoacetate (5), have been isolated from the resin of Bursera fagaroides, together with two known ones, 2,3-demethoxy-secoisolintetralin diacetate (2) and dihydroclusin diacetate (3). The complete structure assignments were obtained by means of (1)H and (13)C NMR spectra.
From the aerial parts of Salvia tiliaefolia Vahl, the known isosalvipuberulin (1) and two new cle... more From the aerial parts of Salvia tiliaefolia Vahl, the known isosalvipuberulin (1) and two new clerodane diterpenoids, salvifolin and tilifodiolide, were isolated. The structure of salvifolin (5) was deduced from spectral data. The structure of tilifodiolide (2) was established by chemical and spectral means and X-ray diffraction analysis.
We have synthesized, characterized and studied the third-order nonlinear optical properties of tw... more We have synthesized, characterized and studied the third-order nonlinear optical properties of two different nanostructures of polydiacetylene (PDA), PDA nanocrystals and PDA nanovesicles, along with silver nanoparticles-decorated PDA nanovesicles. The second molecular hyperpolarizability γ (−ω; ω, −ω, ω) of the samples has been investigated by antiresonant ring interferometric nonlinear spectroscopic (ARINS) technique using femtosecond mode-locked Ti:sapphire laser in the spectral range of 720-820 nm. The observed spectral dispersion of γ has been explained in the framework of three-essential states model and a correlation between the electronic structure and optical nonlinearity of the samples has been established. The energy of two-photon state, transition dipole moments and linewidth of the transitions have been estimated. We have observed that the nonlinear optical properties of PDA nanocrystals and nanovesicles are different because of the influence of chain coupling effects facilitated by the chain packing geometry of the monomers. On the other hand, our investigation reveals that the spectral dispersion characteristic of γ for silver nanoparticles-coated PDA nanovesicles is qualitatively similar to that observed for the uncoated PDA nanovesicles but bears no resemblance to that observed in silver nanoparticles. The presence of silver nanoparticles increases the γ values of the coated nanovesicles slightly as compared to that of the uncoated nanovesicles, suggesting a definite but weak coupling between the free electrons of the metal nanoparticles and π electrons of the polymer in the composite system. Our comparative studies show that the arrangement of polymer chains in polydiacetylene nanocrystals is more favourable for higher nonlinearity.
La oxidación con reactivos suaves del 1,2 diol de la unidad del azúcar de algunas asclepinas proc... more La oxidación con reactivos suaves del 1,2 diol de la unidad del azúcar de algunas asclepinas procede sin la ruptura oxidativa del enlace C-C del glicol. Sin embargo se observa una posterior migración [1,2] para obtener un producto de contracción de anillo en la parte del azúcar.
The Heck Reaction of Allylic Alcohols Catalyzed by an Air-Stable Phosphinito Complex of Palladium... more The Heck Reaction of Allylic Alcohols Catalyzed by an Air-Stable Phosphinito Complex of Palladium(II).-The regioselective method allows access to functionalized aldehydes, ketones and aromatic allylic alcohols thus opening the way to biologi
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Acta Crystallographica Section C Crystal Structure Communications, 2001
The absolute configuration of the neoclerodane glycoside amarisolide, presented here as the monoh... more The absolute configuration of the neoclerodane glycoside amarisolide, presented here as the monohydrate, C26H36O9·H2O, has been determined by association with the known configuration of the glucose moiety. Its structure was established as 2β-(O-β-d-glucopyranosyl)neocleroda-3,13(16),14-trien-15,16-epoxy-18,19-olide. Extensive hydrogen bonding among the hydroxyl groups of the sugar moiety forms layers which are interconnected by water molecules.
Two new p-cymene ruthenium(II) complexes containing as additional ligands N-methylpiperazine ([(η... more Two new p-cymene ruthenium(II) complexes containing as additional ligands N-methylpiperazine ([(η 6-p-cymene)RuCl 2 (CH 3 NH(CH 2) 4 NH)]PF 6 , complex 1) or vitamin K 3-thiosemicarbazone ([(η 6-p-cymene)RuCl 2 (K 3 tsc)], complex 2) were synthesized starting from [(η 6-p-cymene) 2 RuCl 2 ] 2 and the corresponding ligand. The complexes were characterized by elemental analysis, IR, electronic absorption and NMR spectroscopy. The X-ray crystal structure determination of complex 1 revealed "piano-stool" geometry. The differences in the cytotoxic activity of the two complexes are discussed in terms of the ligand present.
The oxidation with mild reagents of the sugar moiety of some asclepines proceeds without oxidativ... more The oxidation with mild reagents of the sugar moiety of some asclepines proceeds without oxidative cleavage of the glycol C-C bond. Nevertheless, a further (1,2) migration to afford the ring contraction of the sugar moiety is observed. Key word: Asclepia linaria, cardenolides, asclepines, gomphoside, oxidations.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
A montmorillonite clay from the State of Durango, Mexico, was used as catalyst. The clay was acti... more A montmorillonite clay from the State of Durango, Mexico, was used as catalyst. The clay was activated with trifluoromethane sulfonic acid and used to study the condensation of different acetophenones in refluxing benzene to produce triphenylbenzenes, β-methylchalcones and pyrylium salts. This catalytic procedure afforded a new simple one-step method for the synthesis of complex organic molecules through the C-C bonds formation and the counter ion for the pyrylium salt. A proposed mechanism of the isolated compounds is discussed as well as their identification by spectroscopic methods and by comparison with reported data, acquired from the previously synthesized derivatives by other synthetic methods.
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