Alejandro Barrero - Profile on Academia.edu (original) (raw)

Papers by Alejandro Barrero

Research paper thumbnail of Tetrahedron Letters

Nature, 1959

A new strategy for the synthesis of (+)-vernolepin (1), (+)-vernodalin (2), and (+)-8-deoxyvernol... more A new strategy for the synthesis of (+)-vernolepin (1), (+)-vernodalin (2), and (+)-8-deoxyvernolepin (3), from the accessible germacrolides (+)-salonitenolide ( ) and (+)-costunolide (5), has been developed. The key steps in the synthesis are a Cope rearrangement from the germacradiene to the elemadiene skeleton, the cyclization of a trans-fused d-lactone from an epoxy ester, and an unusual sulfene elimination, which promotes a reaction cascade leading to the 2-oxa-cis-decalin skeleton.

Research paper thumbnail of Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos

k 45 Fecha de publicación del folleto de patente: 01.01.2000 k 74 Agente: No consta k 54 Título: ... more k 45 Fecha de publicación del folleto de patente: 01.01.2000 k 74 Agente: No consta k 54 Título: Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos. k 57 Resumen: Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos. La presente invención consiste en sendos procedimientos de síntesis de (4 a S, 6 a R, 12 a R, 12 b R) 1,2,3,4,4a,5,6,6a,12a,12b -decahidro -10 -hidroxi -4,4,6a,12b -tetrametil -9H -benzo[a]xanten -9ona, más conocido como (+)-puupehenona, sustancia con propiedades antibacterianas, antifúngicas e inhibidor de la proteína de transferencia del colesteril éster, a partir de (-)-esclareol y de (-)-drimenol, como precursores terpénicos, y aldehido protocatecuico como precursor aromático. En ambos procedimientos es clave la preparación de 1,2-Di-0-bencil -4 -bromo -5 -0 -tert -butildimetilsililbencenotriol como sintón aromático. La condensación del organolítico derivado de éste con 8α -Acetoxi -11 -drimanal en el primer procedimiento, y con drimenal, en el segundo, permite construir el esqueleto carbonado de puupehenona. Se logra la ciclación estereoselectiva hasta el sistema piránico mediante un proceso de alcoxiselenilación.

Research paper thumbnail of Procedimiento para la obtención de productos olorosos tipo ámbar gris a partir de esclareol

Procedimiento para la obtención de productos olorosos tipo ámbar gris a partir de esclareol. 57 R... more Procedimiento para la obtención de productos olorosos tipo ámbar gris a partir de esclareol. 57 Resumen: Procedimiento para la obtención de productos olorosos tipo ámbar gris a partir de esclareol. La presente invención consiste en sendos procedimientos para la obtención de (-)-8α,12-epoxi-13,14,15,16-tetranorlabdano, más conocido como (-)-Ambrox, a partir de esclareol. Mediante tratamiento de esclareol con permanganato potásico y bisulfato potásico se obtiene 13,14,15, 16-tetranorlabdano-8α,12-γ-lactona, también conocida como nor-ambreinolida, que se reduce directamente hasta (-)-ambrox mediante tratamiento con borohidruro sódico en presencia de yoduro de cinc o con borohidruro potásico en presencia de trifluoruro de boro-eterato. Alternativamente, la reducción de la γ-lactona con borohidruro potásico o con vitride conduce a 13,14,15,16-tetranorlabdano-8α,12-diol, cuya ciclación hasta (-)-ambrox se efectúa mediante tratamiento con bromotricloruro de carbono y trifenilfosfina.

Research paper thumbnail of Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales

k 45 Fecha de publicación del folleto de patente: 01.08.94 k 74 Agente: No consta k 54 Título: Pr... more k 45 Fecha de publicación del folleto de patente: 01.08.94 k 74 Agente: No consta k 54 Título: Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales. k 57 Resumen: Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales. La presente invención consiste en sendos procedimientos de síntesis de (-)-8a,12-epoxi-13,14,15.16-tetranorlabdano, más conocido como (-)-Ambrox (nombre registrado por Firmenich, S.A.), a partir de esclareol y cisabienol. Durante los procedimientos planteados se sintetizan también los siguientes productos inter-

Research paper thumbnail of Germacrone Derivatives as new Insecticidal and Acaricidal Compounds: A Structure-Activity Relationship

Molecules, 2019

Currently, the use of synthetic pesticides is the main method of plant protection applied in agri... more Currently, the use of synthetic pesticides is the main method of plant protection applied in agri- and horticulture. However, its excessive use leads to the development of pesticide resistance, a contamination of the environment, toxicity to non-target organisms, and risks for human health. With the ultimate aim of contributing to the develop of a more sustainable pest management, we used the natural product germacrone (compound 1), reported to possess significant insecticidal activity, as starting material for the generation of molecular diversity (2–24). Some of the generated derivatives are natural compounds, such as 1,10-epoxygermacrone (2), 4,5-epoxygermacrone (3), gajutsulactone A (7), germacrol (11), isogermacrone (14), 9-hydroxyeudesma-3,7(11)dien-6-one (19), eudesma-4,7(11),dien-8-one (20), eudesma-3,7(11)-dien-8-one (21) and eudesma-4(15),7(11)-dien-8-one (22). Compounds, 7,11-9,10-diepoxigermacr-4,5-en-8-ol (17), 7,11-epoxieudesma-4,7(11)-dien-8-one (23) and 7,11-epoxieud...

Research paper thumbnail of Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos

k 45 Fecha de publicación del folleto de patente: 01.01.2000 k 74 Agente: No consta k 54 Título: ... more k 45 Fecha de publicación del folleto de patente: 01.01.2000 k 74 Agente: No consta k 54 Título: Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos. k 57 Resumen: Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos. La presente invención consiste en sendos procedimientos de síntesis de (4 a S, 6 a R, 12 a R, 12 b R) 1,2,3,4,4a,5,6,6a,12a,12b -decahidro -10 -hidroxi -4,4,6a,12b -tetrametil -9H -benzo[a]xanten -9ona, más conocido como (+)-puupehenona, sustancia con propiedades antibacterianas, antifúngicas e inhibidor de la proteína de transferencia del colesteril éster, a partir de (-)-esclareol y de (-)-drimenol, como precursores terpénicos, y aldehido protocatecuico como precursor aromático. En ambos procedimientos es clave la preparación de 1,2-Di-0-bencil -4 -bromo -5 -0 -tert -butildimetilsililbencenotriol como sintón aromático. La condensación del organolítico derivado de éste con 8α -Acetoxi -11 -drimanal en el primer procedimiento, y con drimenal, en el segundo, permite construir el esqueleto carbonado de puupehenona. Se logra la ciclación estereoselectiva hasta el sistema piránico mediante un proceso de alcoxiselenilación.

Research paper thumbnail of Procedimiento para la obtención de productos olorosos tipo ámbar gris a partir de esclareol

Research paper thumbnail of (3S,6R)-3,6-dihydroxy-10-methylundecanoic acid and a trimeric diester derivative from Lafuentea rotundifolia

Tetrahedron Letters, 1995

Two new carboxylic acids, 1 and 6, have been isolated from the aerial parts of Lafuentea rotundif... more Two new carboxylic acids, 1 and 6, have been isolated from the aerial parts of Lafuentea rotundifolia Lag. (Scrophulariaceae). The structural determination was performed by spectroscopic methods and chemical correlations, the absolute stereochemistry being established by Mosher's method. Both substances have a fatty acid-type structure with an unusual pattern. Continuing studies on the chemical composition of aromatic and/or medicinal plants endemic to Andalusia (Spain), two new acids, 1 and 6, have been isolated (as their methyl ester derivatives) from the chloroform ~ OMe H H Methyl ester la is a white solid (mp 56-7°C) with a [(~]D -11.1 ° (c 1.00, CHC13). Although its EIMS did not show the molecular peak, the presence of the fragments at m/z 213 ([M-H20-CH3] +) and 210 ([M-2H20] +) along with the IH and I3C NMR data 3 suggest the molecular formula C13H2604 . Compound la was easily

Research paper thumbnail of Stereochemistry of 14-hydroxy-β-caryophyllene and related compounds

Tetrahedron, 1995

The stemchemistry of derivatives with the caryophyllenc skeleton (4.11 .l l-trimethyl-8-methykn b... more The stemchemistry of derivatives with the caryophyllenc skeleton (4.11 .l l-trimethyl-8-methykn bicycle [7,2] undee4cne) have pmentcd a challeqc to organic chemists for years. In 1964 Corey et al.1 synthesized three (l-3) of the four isomeric hydmcarhms and, later, Bohlmann and zdaoz isolated the strained 9-q@caryophyiknc: (4) from Ewyops br-. However, the strucmd analysis of the auyo@ylkncs ls ls 2, RICH:,

Research paper thumbnail of Procedimiento para la preparación de productos olorosos tipo ámbar gris a partir de ácidos comúnicos

k 45 Fecha de publicación del folleto de patente: 01.03.96 k 74 Agente: No consta k 54 Título: Pr... more k 45 Fecha de publicación del folleto de patente: 01.03.96 k 74 Agente: No consta k 54 Título: Procedimiento para la preparación de productos olorosos tipo ámbar gris a partir de ácidos comúnicos.

Research paper thumbnail of Naupliolide, a sesquiterpene lactone with a novel tetracyclic skeleton from Nauplius graveolens subsp. odorus

Tetrahedron Letters, 2006

The aerial parts of Nauplius graveolens subsp. odorus (Schousb) Wikl. afforded a novel sesquiterp... more The aerial parts of Nauplius graveolens subsp. odorus (Schousb) Wikl. afforded a novel sesquiterpene lactone (1) named naupliolide together with the known 6,7,9,10-tetradehydroasteriscanolide 2 and asteriscunolides A-D 3a-d. The structure of compound 1 corresponds to a novel skeleton of 14,15-dimethyl-7,13-dioxotricyclic[6.4.0.0 9,11 ]dodeca-12,13-olide, and was established on the basis of spectroscopic methods including 2D-NMR. The coexistence of naupliolide 1 together with the structurally related sesquiterpene lactones asterisculolides A-D (3a-d) and 6,7,9,10-tetradehydroasteriscanolide 2, seems to indicate their biosynthetic relationship.

Research paper thumbnail of Titanocene-catalysed, selective reduction of ketones in aqueous media. A safe, mild, inexpensive procedure for the synthesis of secondary alcohols via radical chemistry

Tetrahedron Letters, 2003

We report here a novel procedure for the reduction of ketones to secondary alcohols using catalyt... more We report here a novel procedure for the reduction of ketones to secondary alcohols using catalytic quantities of commercially available Cp 2 TiCl 2 , inexpensive Zn dust and water as proton source. Mechanistically the reaction presumably proceeds via titanoxy radicals. In practice this reduction process has significant advantages: it shows an interesting selectivity pattern, takes place under mild conditions using safe, cheap reagents and does not require anhydrous solvents. The proton-donor activity of water under these conditions avoids the use of the frequently poisonous hydrogen-atom donors generally required to reduce free radicals. This procedure is also highly convenient for synthesising deuterium-labelled alcohols employing relatively inexpensive D 2 O as deuterium source.

Research paper thumbnail of Junicedranol, a sesquiterpene with a novel carbon skeleton from Juniperus oxycedrus ssp. macrocarpa

Tetrahedron Letters, 1995

Junicedranol 1, a sesquiterpene with a novel carbon skeleton, has been isolated from the essentia... more Junicedranol 1, a sesquiterpene with a novel carbon skeleton, has been isolated from the essential oil of the wood of Juniperus oxycedrus ssp. macrocarpa. The structure was determined by the

Research paper thumbnail of Synthesis of (+)-vernolepin related compounds from germacranolides

Tetrahedron Letters, 1995

+)-8- O-acetyl-l,2,ll,13-tetrahydro-8-epi -vernolepin (11) was synthesized from salonitenolide (4... more +)-8- O-acetyl-l,2,ll,13-tetrahydro-8-epi -vernolepin (11) was synthesized from salonitenolide (4). The key steps were the Cope rearrangement of the germacradiene skeleton to elemadiene and the long-range functionalization at C-14, which allows the intramolecular cyclisation

Research paper thumbnail of Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales

k 45 Fecha de publicación del folleto de patente: 01.08.94 k 74 Agente: No consta k 54 Título: Pr... more k 45 Fecha de publicación del folleto de patente: 01.08.94 k 74 Agente: No consta k 54 Título: Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales. k 57 Resumen: Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales. La presente invención consiste en sendos procedimientos de síntesis de (-)-8a,12-epoxi-13,14,15.16-tetranorlabdano, más conocido como (-)-Ambrox (nombre registrado por Firmenich, S.A.), a partir de esclareol y cisabienol. Durante los procedimientos planteados se sintetizan también los siguientes productos inter-

Research paper thumbnail of Two sesquilignans from the wood of Abies marocana

Phytochemistry, 1996

From the chloroform extract of the wood of Abies rnarocana, consisting mainly of lignans, the ace... more From the chloroform extract of the wood of Abies rnarocana, consisting mainly of lignans, the acetoxyl derivatives of the new sesquilignans, 4,4",7",9,9"-pentahydroxy-3,3',3"-trimethoxy-4',8":7,9'-bis-epoxy-8,8'-sesquineolignan and 4 were isolated; the trivial names, sesquimarocanols A and B, were subsequently assigned, respectively. Also, (9'R)-9'-hydroxylariciresinol tetraacetate, (7'R)-7'-hydroxylariciresinoi tetraacetate and sesquipinsapol B pentaacetate, which had previously only been found in A. pinsapo, were isolated, together with some well known compounds. The new structures were established by spectroscopic methods. Certain cytotoxic activity assays were performed on the new compounds.

Research paper thumbnail of Pterocarpans from Ononis viscosa subsp. breviflora

Phytochemistry, 1998

Pterocarpin, homopterocarpin, medicarpin, maackiain, and three new compounds, 2-hydroxy-4methoxy-... more Pterocarpin, homopterocarpin, medicarpin, maackiain, and three new compounds, 2-hydroxy-4methoxy-6-(13-hydroxy-2-oxotridecyl)benzoic acid, 1 lb-hydroxy-I lb, l-dihydromedicarpin and 1 lb-hydroxy-11 b, l-dihydromaackiain were identified as minor components in a chloroform extract of Ononis viscosa subsp. breviflora.

Research paper thumbnail of Configuration and Leishmanicidal Activity of (−)-Argentilactone Epoxides

Natural Product Research, 2006

Epoxidation of argentilactone (1) with m-chloroperbenzoic acid gave a diasteromeric mixture of 2 ... more Epoxidation of argentilactone (1) with m-chloroperbenzoic acid gave a diasteromeric mixture of 2 and 3 in a ratio 1.8 : 1, with total yield 60%. The configuration of 7,8-oxirane ring for both diasteromers was determined by NMR analysis. Reaction of 1 with urea hydrogen peroxide gave the 3,4-epoxide (4) in 65% yield. The in vitro activity of 2, 3, 4 and argentilactone against Leishmania amazonensis was tested, only epoxides (2) and (3) showed leishmanicidal effect.

Research paper thumbnail of Two New Cinnamyl Isovalerate Derivatives from Juniperus thurifera Leaves

Journal of Natural Products, 1986

Research paper thumbnail of Preparation, Stereochemistry, and Cytotoxic Activity of the Melampolides from Mikania minima

Journal of Natural Products, 2000

The semisyntheses of melampolides 1 and 2, previously found in Mikania minima, were carried out i... more The semisyntheses of melampolides 1 and 2, previously found in Mikania minima, were carried out in order to confirm their chemical structures and to establish their absolute configurations. Their conformational analyses, performed using molecular mechanics, experimental 1 H NMR coupling constants, and NOE experiments, showed a preferred DU conformer in solution at room temperature. The cytotoxic activities of 1 and 2 against three tumor cell lines were also determined. Conjugated aldehyde 2 showed higher activity than alcohol 1.

Research paper thumbnail of Tetrahedron Letters

Nature, 1959

A new strategy for the synthesis of (+)-vernolepin (1), (+)-vernodalin (2), and (+)-8-deoxyvernol... more A new strategy for the synthesis of (+)-vernolepin (1), (+)-vernodalin (2), and (+)-8-deoxyvernolepin (3), from the accessible germacrolides (+)-salonitenolide ( ) and (+)-costunolide (5), has been developed. The key steps in the synthesis are a Cope rearrangement from the germacradiene to the elemadiene skeleton, the cyclization of a trans-fused d-lactone from an epoxy ester, and an unusual sulfene elimination, which promotes a reaction cascade leading to the 2-oxa-cis-decalin skeleton.

Research paper thumbnail of Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos

k 45 Fecha de publicación del folleto de patente: 01.01.2000 k 74 Agente: No consta k 54 Título: ... more k 45 Fecha de publicación del folleto de patente: 01.01.2000 k 74 Agente: No consta k 54 Título: Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos. k 57 Resumen: Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos. La presente invención consiste en sendos procedimientos de síntesis de (4 a S, 6 a R, 12 a R, 12 b R) 1,2,3,4,4a,5,6,6a,12a,12b -decahidro -10 -hidroxi -4,4,6a,12b -tetrametil -9H -benzo[a]xanten -9ona, más conocido como (+)-puupehenona, sustancia con propiedades antibacterianas, antifúngicas e inhibidor de la proteína de transferencia del colesteril éster, a partir de (-)-esclareol y de (-)-drimenol, como precursores terpénicos, y aldehido protocatecuico como precursor aromático. En ambos procedimientos es clave la preparación de 1,2-Di-0-bencil -4 -bromo -5 -0 -tert -butildimetilsililbencenotriol como sintón aromático. La condensación del organolítico derivado de éste con 8α -Acetoxi -11 -drimanal en el primer procedimiento, y con drimenal, en el segundo, permite construir el esqueleto carbonado de puupehenona. Se logra la ciclación estereoselectiva hasta el sistema piránico mediante un proceso de alcoxiselenilación.

Research paper thumbnail of Procedimiento para la obtención de productos olorosos tipo ámbar gris a partir de esclareol

Procedimiento para la obtención de productos olorosos tipo ámbar gris a partir de esclareol. 57 R... more Procedimiento para la obtención de productos olorosos tipo ámbar gris a partir de esclareol. 57 Resumen: Procedimiento para la obtención de productos olorosos tipo ámbar gris a partir de esclareol. La presente invención consiste en sendos procedimientos para la obtención de (-)-8α,12-epoxi-13,14,15,16-tetranorlabdano, más conocido como (-)-Ambrox, a partir de esclareol. Mediante tratamiento de esclareol con permanganato potásico y bisulfato potásico se obtiene 13,14,15, 16-tetranorlabdano-8α,12-γ-lactona, también conocida como nor-ambreinolida, que se reduce directamente hasta (-)-ambrox mediante tratamiento con borohidruro sódico en presencia de yoduro de cinc o con borohidruro potásico en presencia de trifluoruro de boro-eterato. Alternativamente, la reducción de la γ-lactona con borohidruro potásico o con vitride conduce a 13,14,15,16-tetranorlabdano-8α,12-diol, cuya ciclación hasta (-)-ambrox se efectúa mediante tratamiento con bromotricloruro de carbono y trifenilfosfina.

Research paper thumbnail of Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales

k 45 Fecha de publicación del folleto de patente: 01.08.94 k 74 Agente: No consta k 54 Título: Pr... more k 45 Fecha de publicación del folleto de patente: 01.08.94 k 74 Agente: No consta k 54 Título: Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales. k 57 Resumen: Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales. La presente invención consiste en sendos procedimientos de síntesis de (-)-8a,12-epoxi-13,14,15.16-tetranorlabdano, más conocido como (-)-Ambrox (nombre registrado por Firmenich, S.A.), a partir de esclareol y cisabienol. Durante los procedimientos planteados se sintetizan también los siguientes productos inter-

Research paper thumbnail of Germacrone Derivatives as new Insecticidal and Acaricidal Compounds: A Structure-Activity Relationship

Molecules, 2019

Currently, the use of synthetic pesticides is the main method of plant protection applied in agri... more Currently, the use of synthetic pesticides is the main method of plant protection applied in agri- and horticulture. However, its excessive use leads to the development of pesticide resistance, a contamination of the environment, toxicity to non-target organisms, and risks for human health. With the ultimate aim of contributing to the develop of a more sustainable pest management, we used the natural product germacrone (compound 1), reported to possess significant insecticidal activity, as starting material for the generation of molecular diversity (2–24). Some of the generated derivatives are natural compounds, such as 1,10-epoxygermacrone (2), 4,5-epoxygermacrone (3), gajutsulactone A (7), germacrol (11), isogermacrone (14), 9-hydroxyeudesma-3,7(11)dien-6-one (19), eudesma-4,7(11),dien-8-one (20), eudesma-3,7(11)-dien-8-one (21) and eudesma-4(15),7(11)-dien-8-one (22). Compounds, 7,11-9,10-diepoxigermacr-4,5-en-8-ol (17), 7,11-epoxieudesma-4,7(11)-dien-8-one (23) and 7,11-epoxieud...

Research paper thumbnail of Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos

k 45 Fecha de publicación del folleto de patente: 01.01.2000 k 74 Agente: No consta k 54 Título: ... more k 45 Fecha de publicación del folleto de patente: 01.01.2000 k 74 Agente: No consta k 54 Título: Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos. k 57 Resumen: Procedimientos de obtención de (+)-puupehenona a partir de terpenoides bicíclicos. La presente invención consiste en sendos procedimientos de síntesis de (4 a S, 6 a R, 12 a R, 12 b R) 1,2,3,4,4a,5,6,6a,12a,12b -decahidro -10 -hidroxi -4,4,6a,12b -tetrametil -9H -benzo[a]xanten -9ona, más conocido como (+)-puupehenona, sustancia con propiedades antibacterianas, antifúngicas e inhibidor de la proteína de transferencia del colesteril éster, a partir de (-)-esclareol y de (-)-drimenol, como precursores terpénicos, y aldehido protocatecuico como precursor aromático. En ambos procedimientos es clave la preparación de 1,2-Di-0-bencil -4 -bromo -5 -0 -tert -butildimetilsililbencenotriol como sintón aromático. La condensación del organolítico derivado de éste con 8α -Acetoxi -11 -drimanal en el primer procedimiento, y con drimenal, en el segundo, permite construir el esqueleto carbonado de puupehenona. Se logra la ciclación estereoselectiva hasta el sistema piránico mediante un proceso de alcoxiselenilación.

Research paper thumbnail of Procedimiento para la obtención de productos olorosos tipo ámbar gris a partir de esclareol

Research paper thumbnail of (3S,6R)-3,6-dihydroxy-10-methylundecanoic acid and a trimeric diester derivative from Lafuentea rotundifolia

Tetrahedron Letters, 1995

Two new carboxylic acids, 1 and 6, have been isolated from the aerial parts of Lafuentea rotundif... more Two new carboxylic acids, 1 and 6, have been isolated from the aerial parts of Lafuentea rotundifolia Lag. (Scrophulariaceae). The structural determination was performed by spectroscopic methods and chemical correlations, the absolute stereochemistry being established by Mosher's method. Both substances have a fatty acid-type structure with an unusual pattern. Continuing studies on the chemical composition of aromatic and/or medicinal plants endemic to Andalusia (Spain), two new acids, 1 and 6, have been isolated (as their methyl ester derivatives) from the chloroform ~ OMe H H Methyl ester la is a white solid (mp 56-7°C) with a [(~]D -11.1 ° (c 1.00, CHC13). Although its EIMS did not show the molecular peak, the presence of the fragments at m/z 213 ([M-H20-CH3] +) and 210 ([M-2H20] +) along with the IH and I3C NMR data 3 suggest the molecular formula C13H2604 . Compound la was easily

Research paper thumbnail of Stereochemistry of 14-hydroxy-β-caryophyllene and related compounds

Tetrahedron, 1995

The stemchemistry of derivatives with the caryophyllenc skeleton (4.11 .l l-trimethyl-8-methykn b... more The stemchemistry of derivatives with the caryophyllenc skeleton (4.11 .l l-trimethyl-8-methykn bicycle [7,2] undee4cne) have pmentcd a challeqc to organic chemists for years. In 1964 Corey et al.1 synthesized three (l-3) of the four isomeric hydmcarhms and, later, Bohlmann and zdaoz isolated the strained 9-q@caryophyiknc: (4) from Ewyops br-. However, the strucmd analysis of the auyo@ylkncs ls ls 2, RICH:,

Research paper thumbnail of Procedimiento para la preparación de productos olorosos tipo ámbar gris a partir de ácidos comúnicos

k 45 Fecha de publicación del folleto de patente: 01.03.96 k 74 Agente: No consta k 54 Título: Pr... more k 45 Fecha de publicación del folleto de patente: 01.03.96 k 74 Agente: No consta k 54 Título: Procedimiento para la preparación de productos olorosos tipo ámbar gris a partir de ácidos comúnicos.

Research paper thumbnail of Naupliolide, a sesquiterpene lactone with a novel tetracyclic skeleton from Nauplius graveolens subsp. odorus

Tetrahedron Letters, 2006

The aerial parts of Nauplius graveolens subsp. odorus (Schousb) Wikl. afforded a novel sesquiterp... more The aerial parts of Nauplius graveolens subsp. odorus (Schousb) Wikl. afforded a novel sesquiterpene lactone (1) named naupliolide together with the known 6,7,9,10-tetradehydroasteriscanolide 2 and asteriscunolides A-D 3a-d. The structure of compound 1 corresponds to a novel skeleton of 14,15-dimethyl-7,13-dioxotricyclic[6.4.0.0 9,11 ]dodeca-12,13-olide, and was established on the basis of spectroscopic methods including 2D-NMR. The coexistence of naupliolide 1 together with the structurally related sesquiterpene lactones asterisculolides A-D (3a-d) and 6,7,9,10-tetradehydroasteriscanolide 2, seems to indicate their biosynthetic relationship.

Research paper thumbnail of Titanocene-catalysed, selective reduction of ketones in aqueous media. A safe, mild, inexpensive procedure for the synthesis of secondary alcohols via radical chemistry

Tetrahedron Letters, 2003

We report here a novel procedure for the reduction of ketones to secondary alcohols using catalyt... more We report here a novel procedure for the reduction of ketones to secondary alcohols using catalytic quantities of commercially available Cp 2 TiCl 2 , inexpensive Zn dust and water as proton source. Mechanistically the reaction presumably proceeds via titanoxy radicals. In practice this reduction process has significant advantages: it shows an interesting selectivity pattern, takes place under mild conditions using safe, cheap reagents and does not require anhydrous solvents. The proton-donor activity of water under these conditions avoids the use of the frequently poisonous hydrogen-atom donors generally required to reduce free radicals. This procedure is also highly convenient for synthesising deuterium-labelled alcohols employing relatively inexpensive D 2 O as deuterium source.

Research paper thumbnail of Junicedranol, a sesquiterpene with a novel carbon skeleton from Juniperus oxycedrus ssp. macrocarpa

Tetrahedron Letters, 1995

Junicedranol 1, a sesquiterpene with a novel carbon skeleton, has been isolated from the essentia... more Junicedranol 1, a sesquiterpene with a novel carbon skeleton, has been isolated from the essential oil of the wood of Juniperus oxycedrus ssp. macrocarpa. The structure was determined by the

Research paper thumbnail of Synthesis of (+)-vernolepin related compounds from germacranolides

Tetrahedron Letters, 1995

+)-8- O-acetyl-l,2,ll,13-tetrahydro-8-epi -vernolepin (11) was synthesized from salonitenolide (4... more +)-8- O-acetyl-l,2,ll,13-tetrahydro-8-epi -vernolepin (11) was synthesized from salonitenolide (4). The key steps were the Cope rearrangement of the germacradiene skeleton to elemadiene and the long-range functionalization at C-14, which allows the intramolecular cyclisation

Research paper thumbnail of Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales

k 45 Fecha de publicación del folleto de patente: 01.08.94 k 74 Agente: No consta k 54 Título: Pr... more k 45 Fecha de publicación del folleto de patente: 01.08.94 k 74 Agente: No consta k 54 Título: Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales. k 57 Resumen: Procedimientos de obtención de ámbrox a partir de diterpenos labdánicos naturales. La presente invención consiste en sendos procedimientos de síntesis de (-)-8a,12-epoxi-13,14,15.16-tetranorlabdano, más conocido como (-)-Ambrox (nombre registrado por Firmenich, S.A.), a partir de esclareol y cisabienol. Durante los procedimientos planteados se sintetizan también los siguientes productos inter-

Research paper thumbnail of Two sesquilignans from the wood of Abies marocana

Phytochemistry, 1996

From the chloroform extract of the wood of Abies rnarocana, consisting mainly of lignans, the ace... more From the chloroform extract of the wood of Abies rnarocana, consisting mainly of lignans, the acetoxyl derivatives of the new sesquilignans, 4,4",7",9,9"-pentahydroxy-3,3',3"-trimethoxy-4',8":7,9'-bis-epoxy-8,8'-sesquineolignan and 4 were isolated; the trivial names, sesquimarocanols A and B, were subsequently assigned, respectively. Also, (9'R)-9'-hydroxylariciresinol tetraacetate, (7'R)-7'-hydroxylariciresinoi tetraacetate and sesquipinsapol B pentaacetate, which had previously only been found in A. pinsapo, were isolated, together with some well known compounds. The new structures were established by spectroscopic methods. Certain cytotoxic activity assays were performed on the new compounds.

Research paper thumbnail of Pterocarpans from Ononis viscosa subsp. breviflora

Phytochemistry, 1998

Pterocarpin, homopterocarpin, medicarpin, maackiain, and three new compounds, 2-hydroxy-4methoxy-... more Pterocarpin, homopterocarpin, medicarpin, maackiain, and three new compounds, 2-hydroxy-4methoxy-6-(13-hydroxy-2-oxotridecyl)benzoic acid, 1 lb-hydroxy-I lb, l-dihydromedicarpin and 1 lb-hydroxy-11 b, l-dihydromaackiain were identified as minor components in a chloroform extract of Ononis viscosa subsp. breviflora.

Research paper thumbnail of Configuration and Leishmanicidal Activity of (−)-Argentilactone Epoxides

Natural Product Research, 2006

Epoxidation of argentilactone (1) with m-chloroperbenzoic acid gave a diasteromeric mixture of 2 ... more Epoxidation of argentilactone (1) with m-chloroperbenzoic acid gave a diasteromeric mixture of 2 and 3 in a ratio 1.8 : 1, with total yield 60%. The configuration of 7,8-oxirane ring for both diasteromers was determined by NMR analysis. Reaction of 1 with urea hydrogen peroxide gave the 3,4-epoxide (4) in 65% yield. The in vitro activity of 2, 3, 4 and argentilactone against Leishmania amazonensis was tested, only epoxides (2) and (3) showed leishmanicidal effect.

Research paper thumbnail of Two New Cinnamyl Isovalerate Derivatives from Juniperus thurifera Leaves

Journal of Natural Products, 1986

Research paper thumbnail of Preparation, Stereochemistry, and Cytotoxic Activity of the Melampolides from Mikania minima

Journal of Natural Products, 2000

The semisyntheses of melampolides 1 and 2, previously found in Mikania minima, were carried out i... more The semisyntheses of melampolides 1 and 2, previously found in Mikania minima, were carried out in order to confirm their chemical structures and to establish their absolute configurations. Their conformational analyses, performed using molecular mechanics, experimental 1 H NMR coupling constants, and NOE experiments, showed a preferred DU conformer in solution at room temperature. The cytotoxic activities of 1 and 2 against three tumor cell lines were also determined. Conjugated aldehyde 2 showed higher activity than alcohol 1.