Jorge cárdenas

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• Dr.
• Professor at National Autonomous University of Mexico

In the chemical industry, hydrogenation reactions play a significant role by saturating double bonds in vegetable oils. While most selective hydrogenation processes are carried out at high temperatures (120–180 °C), the development of catalytic systems for partial hydrogenation at low temperatures has been scarcely studied. In this context, we inve...

Novel ether-free bond polymer backbones were synthesized through polycondensation in a superacid medium by using p-terphenyl and 4-(1H-imidazol-1-yl)benzaldehyde. The presence of imidazolium groups enabled further modifications through a highly efficient nucleophilic substitution reaction introducing cationic sites essential for anionic transport....

The synthesis of peptides in solution proceeds through successive steps involving the removal of a protecting group and the formation of the peptide bond. While most methodological efforts have focused on the development of new protecting groups and coupling agents, methodologies based on minimal protecting groups have been less explored. In this r...

The use of homogeneous Brønsted acid cocatalysts (such as benzoic acid) in hydroacylation reactions via imine intermediates has been extensively studied. However, the use of heterogeneous cocatalysts has been limited to montmorillonite K10. Thus, we can use other solid acids to increase the efficiency of the reaction. In this study, we describe the...

The use of homogeneous Bronsted acid cocatalysts (such as benzoic acid) in hydroacylation reactions via imine intermediates has been extensively studied, but the use of heterogeneous cocatalysts has been limited to montmorillonite K10. Thus, we can use other solid acids to increase the efficiency of the reaction. Here, we described the effects of s...

Analysis of the effect of steric compression on the chemical shifts of carbons (13C NMR) in diastereoisomers is an accessible strategy for assigning the absolute configuration of secondary alcohols. Here...

The synthesis of four derivatives and the single-crystal X-ray structures of six 9-trifluoromethylxanthenediols (TFXdiols) I-VI are analyzed in this work. These compounds were obtained through superacid-catalyzed condensation of dihydroxybenzenes with 1,1,1-trifluoroacetone or 2,2,2-trifluoroacetophenone. The title molecules have a convex molecular...

The palladium-catalysed reaction of aryl halides and allylic alcohols is an attractive method for obtaining α,β-unsaturated aldehydes and ketones, which represent key intermediates in organic synthesis. In this context, a 1,2,3-triazol-5-ylidene (aNHC)-based palladium(ii) complex formed in situ has been found to be a selective catalyst for the synt...

In this document, we report an efficient synthesis of well-defined, soluble, high molecular weight, film-forming aromatic multifunctional homopolymers bearing two distinct functional groups per repeating unit. The polymers were obtained in nearly quantitative yields by a one-pot, room-temperature, non-stoichiometric superacid-catalyzed step-polymer...

Novel anion exchange membranes (AEMs) were synthesized by superacid-catalyzed step-growth polycondensation of isatine and p-terphenyl at room temperature. The materials obtained were functionalized by a highly efficient nucleophilic substitution reaction to introduce different cationic side chain lengths, this way, different degrees of functionalit...

Synthesis of processable, aromatic pyridine-containing polymers has always been a great challenge. Here, we report for the first time a robust, low-cost synthesis of well defined, high molecular weight, linear, wholly aromatic polymers with rigid ether-bond-free aryl backbones, where the proportion and position of pyridine moieties and spacer lengt...

Three novel fluorinated polymers with ether-bond-free aryl backbones were obtained by one-pot, metal-free, room temperature superacid catalyzed non-stoichiometric step polymerization of 1,1,1-trifluoromethyl acetone with carbazole (CBZ), fluorene (FLN) and 9,9-dimethylfluorene (DFL). ¹H and ¹³C NMR analyses of the polymers revealed their linear str...

Phytochemical investigation of the leaves and flowers from Salvia hirsuta led to the isolation of the five microphyllane-type diterpenoids (1–5), and two flavones (6–7). Hirsutolides constituted new diterpenoids containing a 5-hydroxyfuran-2(5H)-one and were isolated as an epimeric mixture at C-3 and C-15. The structures of the isolated compounds w...

The direct glycosylation of ceramides in supercritical carbon dioxide (scCO2) successfully proceeded to produce β-glycolipids in high yield and with full stereoselectivity. The reaction is promoted by montmorillonite modified with a superacid (CF3SO3H). The value of this protocol was demonstrated in the efficient synthesis of isoglobotrihexosylcera...

A new, high-molecular-weight, aromatic fluorinated ladder polymer has been obtained by the superacid-catalyzed, nonstoichiometric, step polymerization of a xanthenediol with trifluoroacetone. The polymerizations carried out at room temperature in a mixture of trifluoromethanesulfonic acid (CF3SO3H, TFSA) with methylene chloride resulted in a polyme...

An air-stable phosphinito palladium(II) complex (Ph1-Phoxide) has been found to be an efficient catalyst in the formation of C–C bonds. The coupling of terminal alkynes formed gem-1,3-enynes as the only reaction products. Aromatic alkynes can be synthesized from the coupling of terminal alkynes and haloaromatic compounds (Sonogashira coupling). The...

This study presents an efficient functionalization method of methacrylic polymers such as Eudragit L100. The incorporation of phosphate groups results in pH/temperature-sensitive superabsorbent hydrogels. They are characterized spectroscopically by 1H-, 13 C- 31P-NMR and FT-IR. Thermal analyses, powder X-ray diffractometry and scanning electron mic...

The use of montmorillonite, modified with a super-acid (CF3SO3H), in the presence of hydroquinone as a radical scavenger and under a nitrogen atmosphere, induced the formation of tetrasubstituted furans as the major product from benzoins. In the absence of a radical scavenger, the only products obtained were 1,2-diketones.

The synthesis in one-pot reactions and structural characterization of six new tri-n-butyltin(IV) derivatives of Schiff bases are reported. The compounds are derived from a condensation reaction between l-alanine, l-valine, l-isoleucine, l-methionine, l-phenylalanine or l-tryptophan and 3,5-di-tert-butyl-2-hydroxybenzaldehyde. Characterization was c...

Modification of natural montmorillonite can be achieved efficiently through Fe3+ fixation using solutions of Fe(ClO4)3 in NaClO4. An analysis of the process by a pseudo-second order model allowed us to establish that Fe3+ sorption into montmorillonite is a chemical process that involves an exchange of cations from the montmorillonite interstitial s...

Novel, linear, high-molecular-weight single-strand heteroaromatic polymers and copolymers containing 9H-xanthene moieties in the backbone were synthesized by metal-free superacid-catalyzed stoichiometric and nonstoichiometric step-growth polymerizations of carbonyl compounds bearing electron-withdrawing substituents with bisphenols. The electrophil...

Uterine (cervix and corpus) cancer is one of the major causes of mortality in women in Mexico. Organotin carboxylated derivatives have shown high cytotoxic activity against various cell lines of human origin. We describe the synthesis of three new tri-n-butyltin derivatives from 4-oxo-4-(arylamino)butanoic acids; their structures were confirmed usi...

This work presents the results of polymer membranes whose permeability and selectivity combination of properties can be defined through the chemical modification, in the solid state, of the repeating unit of a poly(oxindolebiphenylyene) that bears a −CH2OH group, PN–CH2OH. The chemical modifications are promoted by moderate thermal treatments (160–...

The Copey tree (Clusia rosea) has a large distribution in Cuba and its floral resin is a rich source of polyisoprenylated benzophenones. To determine the presence of these natural products, we carried out a study by HPLC of 21 propolis samples produced by honey bees (Apis mellifera) from different provinces of Cuba. Nemorosone resulted to be the mo...

The synthesis of amides by coupling benzotriazole esters and amines can be achieved conveniently in moderate to excellent yields (50-95%) using a commercial, synthesized, calcined or reconstructed Mg-Al hydrotalcite instead of one of the classic bases (tertiary amines). The experimental results demonstrated that commercial and synthesized hydrotalc...

From the perspective of synthesis, ynones are compounds of considerable interest because of their occurrence in a wide variety of biologically active molecules and as key synthetic intermediates. In this context, a facile and highly efficient synthesis of ynones was developed based on the high reactivity of benzotriazole esters formed in situ. Lith...

A novel series of linear, high-molecular-weight polymers and copolymers was synthesized by one-pot, metal-free superacid-catalyzed reaction of trifluoromethylalkyl (1a-1c) and trifluoromethylaryl (1d-1h) ketones with the linear, nonactivated, multiring aromatic hydrocarbons biphenyl (A), p-terphenyl (B), and p-quaterphenyl (C). The polymerizations...

Two novel triorganotin carboxylate complexes of the biologically active urocanic acid have been synthesized and characterized. Elemental analysis, melting point, spectroscopic techniques – IR, 1H, 13C and 119Sn NMR – mass spectrometry and X‐ray diffraction studies have been used for structural characterization. Crystal structures of the tin(IV) der...

The reactivity of both natural montmorillonite and montmorillonite modified with super acids (CF3SO3H and HClO4) to generate hydrogen peroxide (H2O2) and hydroxyl radicals (˙OH) under both darkness and UV-light irradiation was investigated using EPR spin-trapping spectroscopy. We used the free-radical trapping action of 5,5-dimethyl-1-pyrroline-N-o...

This report presents a general overview of non-stoichiometric step-growth polymerizations (polycondensations). Three kinds of non-stoichiometric polycondensations are defined and discussed for a2 + b2 monomer combinations. Depending on the kinetic scenario and on the experimental conditions, the excess of one monomer either strongly reduces or stro...

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 str...

A highly efficient catalyst in the chemo-, regio-, and stereoselective synthesis of the stilbenes (III) and resveratrol (VI) is presented.

The regioselective method allows access to functionalized aldehydes, ketones and aromatic allylic alcohols thus opening the way to biologically interesting substances.

New azanucleosides were obtained using sulphated zirconia (ZS) as catalyst in the nucleophilic oxirane ring opening reaction of 1-allyl-3-(oxiran-2-ylmethyl)pyrimidine-2,4(1H,3H)-dione and 1-allyl-5-methyl-3-(oxiran-2-ylmethyl)-pyrimidine-2,4(1H,3H)-dione, with (S)-prolinol. The new templates were obtained with good yields following a route which e...

Mechanochemical activation is a practical cogrinding operation used to obtain a solid dispersion of a poorly water soluble drug through changes in the solid state molecular aggregation of drug-carrier mixtures and the formation of noncovalent interactions (hydrogen bonds) between two crystalline solids such as a soluble carrier, lactose, and a poor...

From the aerial parts of Salvia occidentalis (Labiatae) a new diterpenoid with a rearranged neo-clerodane skeleton was isolated. This new compound was named salvioccidentalin and its structure was established by spectroscopic means. A probable biogenetic relationship with salvigenolide from S. fulgens and salvileucalin A and spiroleucantholide from...

From the aerial parts of Salvia mexicana var. mexicana, two C-10 epimers (α and β) of salvimexicanolide were isolated. Our interpretation of the data, especially the ¹³C NMR, led us to conclude that the previously described ¹³C-NMR spectrum of the α-epimer was not accurately assigned and it actually corresponds to the β-epimer. The structures propo...

The presented method for the reduction of carboxylic acids via their 1-hydroxybenzotriazole esters is compatible with a variety of reducible functional groups allowing selective reductions.

Benzotriazole esters, formed in situ from carboxylic acids and HOBt in the presence of EDC, are efficient intermediates in the esterification with tert-butyl alcohol using either DMAP or calcinated hydrotalcite as the base.

From the aerial part of Cuphea hyssopifolia (Lythraceae) diterpenes and flavonoids were isolated. The compounds were identified as: friedelan–3β–ol 1, ursolic acid 2, methyl gállate 3, quercetin 4, quercetin–3–O–α–rhamnopyranoside 5, 1,2,3,4,6–penta–O–galloyl–β–D–glucose 6 and manitol 7.

The structure of kerlinic acid, a neo-clerodane diterpenoid isolated from Salviakeerlii (Labiatae), was deduced from spectral data and chemical correlation with melisodoric acid.

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.

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.

For Abstract see ChemInform Abstract in Full Text.

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.

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 facile and mild macrolactonization reaction of ω-hydroxy acids was developed based on the transesterification of benzotriazole esters. Treatment of ω-hydroxy acids with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and 1-hydroxy benzotriazole (HOBT) in chloroform provided macrolactones in excellent yields. The reactions were performed unde...

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.

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 novel series of linear, high-molecular-weight polymers was synthesized by one-pot, metal-free superacid-catalyzed reaction of isatins (1a−d) with linear, nonactivated, multiring aromatic hydrocarbons: biphenyl (A), p-terphenyl (B), p-quaterphenyl (C), 2-(4-biphenylyl)-6-phenylbenzoxazole (D), 9H-fluorene (E), 9,9-dimethyl-9H-fluorene (F), 2,2′-[2...

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.

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.

Three homoisoflavanones were isolated from the “piña” and leaves of Agave tequilana Weber. The compounds were identified as: 5,7-dihydroxy-3-(4-methoxybenzyl)-chroman-4-one (1), 7-hydroxy-3-(4-hydroxybenzyl)-chroman-4-one (2) and 4’-demethyl-3,9-dihydro-punctatin (3). This is the first phytochemical study carried out to Agave tequilana Weber.

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.

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.

4-Piperidone and 4-alkyl piperidones react selectively with aromatic hydrocarbons in a mixture of trifluoromethanesulfonic acid (TFSA) and CH(2)Cl(2) to give linear polymers, while N-(2-phenethyl)piperidone undergoes self-polymerization to yield virtually 100%-hyperbranched polymer.

In order to show the advantages and limitations of organic electrosynthesis in the total synthesis of a natural product, one of the promising green chemistry techniques in organic chemistry, the synthesis of N-isobutyl-(2E,6Z)-dodecadienamide (3) was undertaken. Chemical and electrochemical routes that use the same intermediates were used to carry...

A new prenylated xanthone, pinetoxanthone (1), and two new pyranochromanones, pinetoric acid I (2) and pinetoric acid II (3), together with 10 known compounds, namely, the triterpenes friedelin and canophyllol, the xanthone macluraxanthone, the pyranochromanone derivatives calophyllic acid, isocalophyllic acid, calolongic acid, apetalic acid, and i...

The synthesis, characterization and cytotoxic properties in vitro of tri-n-butyltin 1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetate (1), tri-phenyltin 1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetate (2), tetra-n-butyltin[bis-1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1H-indole-3-acetato]distannoxane (3) and di-n-butyltin bis-1-(4-...

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 meth...

The absolute configuration of secondary alcohols can be determined by NOE between the diastereotopic protons of the lactam and the protons of the alcohol moieties in some 1-(alkoxymethyl)-methyl-2-pyrrolidone-5-carboxylate derivatives. Two simple methods based on conformational analysis and 1H NMR data have been developed. The main conformer, in al...

Calcined Mg-Al Hydrotalcites x = 0.20, 0.27, 0.33 proved effective catalysts for the lactonization of 10, 12, 15, and 16 hydroxy acid benzotriazole esters to their correspondent macrolactones. This new methodology was used for the lactonization step in the synthesis of Sansalvamide A.

The electrochemical oxidation ((+)Pt-Ni(-)/NH(4)Br/MeOH) of the natural product hispanolone (1a) produced, in high yield (>95%), spiro-tetracyclic compounds 7a-7d as a result of the intramolecular addition of the C-9 hydroxyl group into the C-16 position with the simultaneous addition of a CH(3)O group at the C-15 position of the hispanolone furan...

In the presence of Celite mono and disubstituted alkenes could be alkylated with benzylic halides at room temperature. In order to form the C-C bond, it was necessary to use activated aromatics with alkenes or propargylic esters.

Calcined Mg-Al Hydrotalcites x = 0.20, 0.27, 0.33 proved effective catalysts for the oxirane ring opening reaction with trimethylsilyl azide in n-heptane at room temperature, yielding quantitative silylated vicinal azidohydrins. The catalyst was reused in several cycles presenting a consistent activity.

The known electrochemical synthesis of α,β-(E)-unsaturated esters (Horner–Emmons reaction) was modified in order to achieve the electrolysis in an undivided cell using magnesium as the sacrificial anode. The undivided cell procedure showed advantages over the traditional two-compartment cell methodology. The best yield using undivided cell methodol...

Materiales mesoporosos del tipo Ti-MCM-41 preparados por tratamiento hidrotérmico, se caracterizaron por DRX, SEM, FTIR, Si29-RMN y análisis textural, fueron utilizados en la reacción de apertura nucleofílica de epiclorhidrina con L-prolinol.

De las partes aéreas de Salvia uruapana se aislaron dos diterpenos, salviafaricina y tonalensina ambos previamente descritos en Salvia tonalensis, así como 7-O-luteolina diglucósido peracetilado. La mezcla de los ácidos oleanólico y ursólico se aisló de las fracciones de baja polaridad.

An electrochemical deoxygenation reaction of aliphatic acetates has been developed, using electrogenerated organic amalgams (R4N-Hg). This methodology led us to obtain the deoxygenated product and the alcohol in a 1:1 ratio with total transformation of the starting compound. Examples using the acetates of sarsasapogenin, diosgenin, 16-dehydro-pregn...

An efficient one step procedure for the preparation of (4.3.0) bicyclic N-methylpyrrolidine thymidine derivatives 4, using cycloaddition reaction of the highly reactive non-stabilized azomethine ylide [Y] with 3′,5′-Bis-O-silylthymidines 3.

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 am...

Nemorosone, the major constituent of the floral resin of Clusia rosea was isolated after exhaustive chromatography. This compound was fully characterized as it is in the nature, without methylation as reported before. A keto-enol equilibrium was observed and both isomers were totally characterized by NMR spectroscopic techniques. The previously ann...

Three new modified clerodanes (10, 12, 17) containing a tricyclo[5.4.0.01,3]undecane ring system were isolated from Dodonaea viscosa. These types of compounds have not been found in nature until now, but they have been proposed as hypothetical intermediates in the biogenetic pathway of diterpenes possessing bicyclo[5.4.0]undecane or bicyclo[5.3.0]d...

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and...

Dihydropsuedoivalin (1) was isolated from Stevia tomentosa, which, when treated with base, afforded epidihydropseudoivalin (2). The stereochemistry of 1 and 2 was established by crystallographic X-ray studies of the two derivatives of epidihydropseudoivalin. Treatment of 1 and 2 with Jones's reagent afforded the xanthanolides 3 and 4, respectively.

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 roots of Salvia reptans Jacq. (Labiatae) yielded 8 alpha 9 alpha-epoxy-7-ketoroyleanone I and horminone 2 as the major antimicrobial agents. These isolates were found to be active against Bacillus cereus, Micrococcus luteus, Staphylococcus aureus, Streptococcus faecalis and Escherichia coli (MIC 0.4-2.2 (mu g/ml). Some derivatives were prepared...

A number of cyclic (5a-b) and linear (3a-c; 4b-c) oligomers arose from benzylic alcohols have been synthesized by treatment of 1a-c with a bentonitic earth. A mechanism for the formation of both cyclic and linear oligomers is proposed based on the isolation of the key intermediate; the ethers 2a-c.

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-α-santonine, 4,5-epoxy-α-santonine, 14-acetamide-α-santonine and α-santonic acid. These oxidations were important since there are few methods to oxidize the allylic methy...

An electrochemical methodology for the protection of the ortho-hydroxy-para-benzoquinone functionality has been developed, by a one step formation of the aromatic ethers of the reduced quinone function, improving the yields obtained for this reaction by the classical chemical methods.

The deoxygenation of alcohols by photochemical and electrochemical methods has been studied using the 3-O-S-methyldithiocarbonate derivatives of oleanolic and ursolic methyl esters as models. The use of diethyl phosphite as hydrogen donor was analyzed.

The seco-limonoid trichavensin, structurally related to prieurianin, was isolated from the mature seed material of Trichilia havanensis. Its structure was determined by spectroscopic studies.

A new neo-clerodane glycoside, amarisolide, has been isolated from the aerial parts of Salvia amarissima. Its structure was established as 2β-O-β-D-glucopyranosyl neo-cleroda-3,13(16),14-trien-15,16-epoxy-18,19-olide by chemical and spectroscopic means.

Two examples of catalytic induction with a bentonite clay to form phenylmethanes and aromatic ethers from benzyl derivatives are discussed.

3,4,5-Trimethoxybenzyl alcohol was cyclooligomerized with a bentonite clay used as a catalyst. Results of the crystal structure analysis of the racemic () nonamethoxy[1,1,1]orthocyclophane trimer, C30H36O9, are described. The structure was determined by X-ray diffraction at 293 K and shown to belong to the triclinic space group P [`1]\bar 1 . The c...

Sodium borohydride reduction of hispanolone 1 followed by treatment with acetic acid, produced the borates 6 and 7. Their structures were established by spectral means and X-ray diffraction analysis of 6.

The first triphenylgermanium diorganophosphinodithioates, Ph3GeS(S)PR2 (R  Me, Et, Ph), were synthesized by metathesis reactions between Ph3GeCl and the ammonium or sodium salt of the corresponding dithio acid. The compounds were characterized by IR, MS and multinuclear NMR (1H, 13C, 31P) spectroscopy. The solid state molecular structures of Ph3Ge...

The known ursolic and oleanolic acids, the abietane quinone diterpenes, sessein, and deacetylsessein, together with the also known clerodane diterpenes hardwickiic and clerodermic acids were isolated from the aerial parts of Salvia regla. The structure of a novel compound, reglin, present in this species was established by spectral means as deacety...

Seven abietane and icetexane diterpenoids were isolated from the aerial parts of Salvia candicans. Three were identified as conacytone, icetexone and anastomosine. The other four were new diterpenes, whose structures were established by spectroscopic and chemical means. Two of them had an icetexane skeleton.

Interest in finding biodegradable products possessing a defined biological activity, such as bactericidal, fungicidal, antitumoral, antiviral or pesticidal, has been a driving force in the study of the secondary metabolites of plants, fungi, marine organisms, and others. Phytochemical studies often make use of accumulated ethnobotanical knowledge,...

The catalytic induction and structures of cyclic and linear oligomers from 3,4,5-trimethoxybenzyl alcohol with a bentonite clay as catalyst are discussed.

High-field 2D NMR studies were performed on nine neo-clerodane diterpenoids. Unambiguous assignments of the 13C signals and proton chemical shifts were achieved which led to the revision of some previous assignments.