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Boronic acid-derived salicylidenehydrazone complex (BASHY) dyes with a polymethine backbone were designed to yield efficient red-emitting and two-photon absorbing fluorophores that can be used as markers for astrocytes. The dyes are chemically stable in aqueous solution and do not undergo photodecomposition. Their photophysical properties can be electronically fine-tuned and thereby adapted to potentially different imaging situations and requirements.

The [Ru(bpy)

[Image: see text] In this study, we show that fluorescent boronic-acid derived salicylidenehydrazone complexes (BASHY) can function as fluorescent linkers for bioconjugates that were used to monitor the delivery of the proteasome inhibitor bortezomib (Btz) to HT-29 cancer cells. BASHY complexes were structurally optimized to improve the stability of the complex in buffered conditions (ammonium acetate, pH 7 up to t(1/2) = 40 h), photophysically characterized regarding their fluorescence properties and used in confocal microscopy colocalization studies that revealed their intracellular sequestration by lipid droplets. The accumulation in these hydrophobic organelles limited the hydrolysis of the complex and consequently the drug release, a problem that was circumvented by the conjugation of the BASHY-Btz complex with a cell-penetrating peptide GV1001-C. The conjugate exhibited an improved cytoplasmic availability as confirmed by confocal fluorescence microscopy studies and an improved potency against HT-29 cancer cells (IC(50) = 100 nM) as compared to the nontargeted complex (IC(50) = 450 nM).

The formation of host-guest complexes between seven flavylium cations and water-soluble p-sulfonatocalix[4]arene (SC4) was investigated by UV/vis absorption, fluorescence, and NMR spectroscopies. The results show the cationic guests form complexes with affinities in the submillimolar range. A representative chalcone/flavylium photoswitch was investigated in more detail regarding its pH- and light-triggered interconversion between the two forms. The dramatic affinity differentiation of the SC4 binding of the two switchable species (40 M-1 for the trans-chalcone versus 3.5 × 104 M-1 for the flavylium cation) enables the pH-gated photocontrol of the complexation process. These responsive properties were explored to demonstrate the competitive and selective release of biologically relevant guests from their supramolecular complexes with p-sulfonatocalix[4]arene (SC4), following the principle of AND logic. The guest release can be reverted by the thermally activated reaction of the flavylium ion back to the trans-chalcone.

An o-nitrobenzyl-protected precursor was used as a phototrigger for the release of the diamine cadaverine in polyurethane adhesives based on castor oil as a renewable source of polyol and organic diisocyanates. This resulted in formulations with suitably controlled curing by photoactivation. This material shows faster curing when UV light is applied as compared to curing in the absence of irradiation, which was in situ monitored by rheological measurements. In addition, the adhesion performance is superior, reaching lap shear strength values of up to 4600 kPa, which is unprecedented for bio-based adhesives. On one hand, the in-depth chemical characterization with FTIR spectroscopy revealed that the slow release of cadaverine yields a well-balanced urethane/urea composition with direct impact on adhesion properties. The photocured bioadhesive was shown to bond a variety of surfaces, such as polyethylene or even wood. On the other hand, the direct one-time addition of cadaverine yields a material with approximately the same viscoelastic properties, which were achieved almost immediately as a consequence of the favored fast formation of urea bonds in detriment of urethanes, however, lacking adhesion properties., We are grateful for financial support through the project UHU-1252599, financed by the University of Huelva, in the frame of the European Regional Development Fund (ERDF)-Junta de Andalucía 2014−2020 Operational Programme. A.M.B.-L. acknowledges the Spanish Ministerio de Educación, Cultura y Deporte for the award of a doctoral fellowship (FPU16/03697)., Funding for open access charge: Universidad de Huelva / CBUAUniversity of Huelva, in the frame of the European Regional Development Fund (ERDF)-Junta de Andalucía 2014−2020 Operational Programme. Ministerio de Educación, Cultura y Deporte (FPU16/ 03697) Funding for open acess charge: Universidad de Huelva/CBUA

The light-gated organocatalysis via the release of 4-N,N-dimethylaminopyridine (DMAP) by irradiation of the [Ru(bpy)

A general approach toward the light-induced guest release from cucurbit[7]uril by means of a photoactivatable competitor was devised. An o-nitrobenzyl-caged competitor is photolyzed to generate a competitive guest that can displace cargo from the host macrocycle solely based on considerations of chemical equilibrium. With this method the release of terpene guests from inclusion complexes with cucurbit[7]uril was demonstrated. The binding of the herein investigated terpenes, all being lead fragrant components in essential oils, has been characterized for the first time. They feature binding constants of up to 108 L mol-1 and a high differential binding selectivity (spanning four orders of magnitude for the binding constants for the particular set of terpenes). By fine-tuning the photoactivatable competitor guest, selective and also sequential release of the terpenes was achieved.

[EN] A series of boronic acid derived salicylidenehydrazone (BASHY) complexes was prepared and photophysically characterized. The dye platform can be modified by (a) electronic tuning along the cyanine-type axis via modification of the donor-acceptor pair and (b) functional tuning via the boronic acid residue. On the one hand, approach (a) allows the control of photophysical parameters such as Stokes shift, emission color, and two-photon absorption (2PA) cross section. The resulting dyes show emission light-up behavior in nonpolar media and are characterized by high fluorescence quantum yields (ca. 0.5-0.7) and brightness (ca. 35000-40000 M-1 cm(-1)). Moreover, the 2PA cross sections reach values in the order of 200-300 GM. On the other hand, the variation of the dye structure through the boronic acid derived moiety (approach (b)) enables the functionalization of the BASHY platform for a broad spectrum of potential applications, ranging from biorelevant contexts to optoelectronic materials. Importantly, this functionalization is generally electronically orthogonal with respect to the dye's photophysical properties, which are only determined by the electronic structure of the cyanine-type backbone (approach (a)). Rare exceptions to this generalization are the presence of redox-active residues (such a triphenylamine or pyrene). Finally, the advantageous photophysics is complemented by a significant photostability., The financial support by Spanish MINECO (grants CTQ2014-54729-C2-1-P, CTQ2014-54729-C2-2-P, CTQ2013-41339-P, and CTQ2015-71896-REDT), the Junta de Andalucia (grant P12-FQM-2140), and Portuguese FCT (grants SFRH/BD/94779/2013, PTDC/QEQ-QOR/1434/2014, iMed.ULisboa grant UID/DTP/04138/2013) is gratefully acknowledged.

Summary This work presents a systematic study of the possible interactions in mixtures of the natural antioxidants eugenol, thymol, sesamol and limonene. The antioxidant capacity is measured from the decrease of the DPV signal corresponding to the H2O2 oxidation on a mercury electrode in the presence of the antioxidants. A three-level full factorial design was used to analyse the antioxidant capacity of forty five mixtures. The higher synergistic effect was reached in the mixtures containing eugenol and sesamol (antioxidant capacity increases in a 28.5%). The synergistic and antagonistic effects of the combinations having the lower antioxidant capacity (thymol, sesamol and limonene) ranged between 20.2–26.3% and 8.6–11.8%, respectively. An increase in the eugenol concentration implies a progressive increase in the global synergy, not proportional to the concentration. A possible explanation of the synergy related to the oxidation mechanisms and to the possibility of interaction with the radicals is given.

[EN] The light-gated organocatalysis via the release of 4-N,N-dimethylaminopyridine (DMAP) by irradiation of the [Ru(bpy)(2)(DMAP)(2)](2+)complex with visible light was investigated. As model reaction the acetylation of benzyl alcohols with acetic anhydride was chosen. The pre-catalyst releases one DMAP molecule on irradiation at wavelengths longer than 455 nm. The photochemical process was characterized by steady-state irradiation and ultrafast transient absorption spectroscopy. The latter enabled the observation of the(3)MLCT state and the spectral features of the penta-coordinated intermediate [Ru(bpy)(2)(DMAP)](2+). The released DMAP catalyzes the acetylation of a wide range of benzyl alcohols with chemical yields of up to 99 %. Control experiments revealed unequivocally that it is the released DMAP which takes the role of the catalyst., We are grateful for the financial support by the Spanish Ministry of Science, Innovation, and Universities (grant CTQ2017- 89832-P for U.P.), the University of Huelva (grant UHU-9-542- 2019 for J.F.A.), and the Generalitat Valenciana (PROMETEO program, 2017-075 for P.B.). The experimental assistance of A. Morales and S. Abad in the early stages of the work, as well as the technical support by F. Molina in the determination of the single-crystal X-ray structure of 1-(PF6)2 is acknowledged.

It is well known that spontaneous oxidation is one of the main drawbacks for the industrial use of eco-friendly vegetable oil-based lubricants. Herein a quick and easy synthesis of different molecules belonging to stilbene family is reported, which together with a number of representative natural sources-derived products with antioxidant (AO) capacity have been tested as additives for improving the oxidative stability of a selected bio-lubricating grease formulation. Thus, different gel-like dispersions based on N-acylated chitosan in castor oil also including these additives have been prepared. Gel-like dispersions were characterized through thermogravimetric analysis (TGA), oxidation onset temperature (OOT) and small-amplitude oscillatory shear (SAOS) rheological measurements. These preliminary results demonstrate that, in general, these antioxidants delay N-acylated chitosan-based gel-like dispersions oxidation. However, the AO activity is more relevant in the case of propyl gallate and ascorbic acid palmitate and not so important in the family of stilbene derivatives. On the other hand, the addition of any antioxidant does not qualitatively affect the rheological response but unexpectedly may significantly modify the values of the SAOS functions. Remarkably, the delay of oxidation reactions occurs by exclusively employing natural resources-derived components, being these formulations environmentally acceptable as a whole and potentially employed in specific industrial applications.

Apocarotenoids are metabolites originated by degradation of carotenes through the loss of carbon atoms placed at the side chain of their structure as consequence of oxydative reactions. We present here the first review of apocarotenoids in the fungi mucorales Phycomyces blakesleeanus, Blakeslea trispora and Mucor mucedo. This review is divided into two parts: the first one presents their structures and sources, whereas the second part is dedicated to their chemical synthesis.

Several preparations were obtained from the aerial parts of predomesticated Lavandula luisieri, including the essential oil and ethanolic, hexane, and ethyl acetate extractives. Additionally, pilot plant vapor pressure extraction was carried out at a Several preparations were obtained from the aerial parts of predomesticated Lavandula luisieri, including the essential oil and ethanolic, hexane, and ethyl acetate extractives. Additionally, pilot plant vapor pressure extraction was carried out at a pressure range of 0.5–1.0 bar to give a vapor pressure oil and an aqueous residue. A chemical study of the hexane extract led to the isolation of six necrodane derivatives (1, 2, and 4–7), with four of these (1, 2, 5, and 7) being new, as well as camphor, a cadinane sesquiterpene (9), tormentic acid, and ursolic acid. The EtOAc and EtOH extracts contained a mixture of phenolic compounds with rosmarinic acid being the major component. Workup of the aqueous residue resulted in the isolation of the necrodane 3 and (1R*,2S*,4R*)-p-menth-5-ene-1,2,8-triol (8), both new natural compounds. The structures of the new compounds were established based on their spectroscopic data. The phytotoxic and nematicidal activities of these compounds were evaluated., This work has been partially supported by grants CTQ2012- 38219-C03-01 (Spain), Junta de Andalucia (Excellence Project ́ P08-FQM-3596) Spain, and JAE-CSIC (predoctoral fellowship to L.F.J.).

Several commercially available cellulose derivatives differing in the type of substituent and substitution degree (α-cellulose, methyl cellulose, 2-hydroxyethyl cellulose, methyl 2-hydroxyethyl cellulose and cellulose acetate propionate) have been functionalized with 1,6-hexamethylene diisocyanate (HMDI) and subsequently dispersed in castor oil to obtain chemical oleogels, which can be proposed as lubricating grease formulations completely based on renewable resources. NCO-functionalized cellulose derivatives used as thickening agents and corresponding oleogels were characterized by means of Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Oleogels were also rheologically investigated and gel microstructure determined by atomic force microscope (AFM) observations. Dispersions of the different cellulosic derivatives analyzed provide oleogels with a wide variety of rheological properties, thermal stability and physical appearance. Cellulose derivatives used as thickeners exhibited a reduced thermal resistance after NCO-functionalization due to the inclusion of the HMDI segments in the cellulose structure. However, the resulting oleogels presented suitable thermal resistance. The different rheological responses obtained, from solid-like to weak gels, were found to be basically dependent on the balance between the non-polar and polar substituents molar ratio in the biopolymer structure and the size of these substituents. The presence of non-polar groups reduces cellulose polarity and, therefore, increases the affinity by the oil medium, whereas large substituents seem to hinder the development of the three-dimensional gel network. An empirical correlation between the storage modulus, G ′, and a power function of both the molar ratio [− R polar /− R non-polar ] in each monomer,− R being the different substituents of cellulosic derivatives evaluated, and the ratio of average molecular weight of all substituents to cellulose monomer molecular weight has been proposed to predict the rheological behavior of resulting oleogel formulations.

In this work, several lignocellulose pulps from different origins and/or submitted to different treatments were cross-linked with hexamethylene diisocyanate (HMDI) and further dispersed in castor oil in order to obtain gel-like formulations based on renewable resources, which can be potentially applicable as semisolid lubricants. The rheological and tribological properties attained as well as physical and mechanical stability were suitable to consider these gel-like dispersions as efficient alternatives to traditional lubricating greases. The rheological behavior was evaluated by means of both small-amplitude oscillatory shear tests (SAOS) and viscous flow measurements, at different temperatures. The HMDI/cellulose pulp weight ratio applied in the cross-linking reaction can be used to modify and modulate the consistency and the values of rheological functions of these gel-like dispersions. However, the rheological behavior is not qualitatively affected by the amount of HMDI used as coupling agent. The the...

This work deals with the influence of functionalization degree on the thermogravimetric and rheological behaviour of NCO-functionalized chitosan- and chitin-based oleogels. Chitosan and chitin were functionalized using different proportions of 1,6-hexamethylene diisocyanate (HMDI) and subsequently dispersed in castor oil to promote the chemical reaction between the –NCO group of the modified biopolymer and the –OH group located in the ricinoleic fatty acid chain of castor oil, thus resulting in different oleogels with specific thermogravimetric and rheological characteristics. Biopolymers and oleogels were characterized through Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Small-amplitude oscillatory shear (SAOS) measurements were performed on the oleogels. Oleogels presented suitable thermal resistance, despite the fact that the inclusion of HMDI moieties in the polymer structure led to a reduction in the onset temperature of thermal degradation. The insertion of low amounts of HMDI in both chitin and chitosan produces a drastic reduction in the values of oleogel viscoelastic functions but, above a critical threshold, they increase with the functionalization degree so that isocyanate functionalization results in a chemical tool to modulate oleogel rheological response. Several NCO-functionalized chitosan- and chitin-based oleogel formulations present suitable thermal resistance and rheological characteristics to be proposed as bio-based alternatives to traditional lubricating greases., This work is part of two research projects (CTQ2010-15338 and TEP-1499) sponsored by MINECO-FEDER (70% European cofunding rate) and Junta de Andalucia programmes, respectively. One of the authors (Rocio Gallego) has received a Ph.D. Research Grant from DIGICyT (MINECO). The authors gratefully acknowledge the financial support.

A new approach towards the rapid identification of quality binders to cucurbiturils--those that combine high affinity with high selectivity for a particular homologue--was developed. The assay exploits macrocycle-specific optical fingerprints (colorimetric or fluorimetric) of carefully selected indicators dyes. The screening of a guest library revealed known (e.g., adamantane derivatives) and new (e.g., terpenes) quality binders. The predictive power of the assay was underpinned by the modeling of the involved thermodynamic equilibria.

The synthesis of a cyclohexane skeleton possessing different oxygenated functional groups at C–3, C–8 and C–9, and a 1,6-double bond has been accomplished in 10 steps with an overall 17% yield. This compound is a key intermediate for access to a wide range of compounds of the bioactive trisporoid family. The synthetic sequence consists of the preparation of a properly functionalized epoxygeraniol derivative, and its subsequent stereoselective cyclization mediated by Ti(III). This last step implies a domino process that starts with a homolytic epoxide opening followed by a radical cyclization and regioselective elimination. This concerted process gives access to the cyclohexane moiety with stereochemical control of five of its six carbon atoms., This project was supported by the Spanish Ministry of Economy and Competitiveness (project CTQ2010-16818-BQ).

[5]Pseudorotaxanes can be obtained by self-sorting using heteroditopic guests and various cucurbituril homologues as hosts. The assembly and chemically induced disassembly of the pseudorotaxanes can be monitored by measuring the fluorescence of the anthracene guest in solution. Mass spectral evidence for the supramolecular assemblies is obtained in the gas phase. The disassembly in the gas phase can be achieved by collision-induced dissociation leading to the corresponding [2]- and [3]pseudorotaxanes., We acknowledge the financial support of the Ministerio de Econom &a y Competitividad, Madrid, Spain (grants CTQ2011-28390 and CTQ2014-54729-C2-1-P for U.P. and PhD fellowship BES- 2015–074458 for Z.D.), the Junta de Andaluc&a (grant P12-FQM- 2140 for U.P.), and the Fundażo para a CiÞncia e a Tecnologia, Lisbon, Portugal (grant SFRH/BD/81628/2011 for C.P.C.). H.S.E.-S. is grateful for a postdoctoral stipend from the Egyptian Ministry of Higher Education, Cairo., We acknowledge the financial support of the Ministerio de Economia y Competitividad, Madrid, Spain (grants CTQ2011-28390 and CTQ2014-54729-C2-1-P for U.P. and PhD fellowship BES2015-074458 for Z.D.), the Junta de Andalucia (grant P12-FQM2140 for U.P.), and the Fundacao para a Ciencia e a Tecnologia, Lisbon, Portugal (grant SFRH/BD/81628/2011 for C.P.C.). H.S.E.-S. is grateful for a postdoctoral stipend from the Egyptian Ministry of Higher Education, Cairo.

This work deals with the selective incorporation of reactive isocyanate groups into methyl cellulose in order to be used as reactive thickening agent in castor oil. Resulting gel-like dispersions may have potential applications as green lubricating greases formulated from renewable resources. Two different isocyanate-functionalized methyl cellulose-based polymers were obtained by reaction of methyl cellulose with 1,6-hexamethylene diisocyanate. The functionalization degree, from fully functionalized to a certain number of free hydroxyl groups (58:36:6 ratio between –OMe, –NCO and free –OH groups), was controlled by modifying the reagents molar ratio. These polymers were characterized through nuclear magnetic resonance of protons (1H-NMR), Fourier transform infrared spectroscopy and thermogravimetric analysis (TGA). Thermal and rheological responses of oleogels prepared by dispersing these polymers in castor oil were studied by means of TGA analysis and small-amplitude oscillatory shear measurements. The evolution of linear viscoelasticity functions with frequency of the oleogel containing isocyanate-functionalized methyl cellulose with lower –NCO content is quite similar to that found for traditional lithium lubricating greases. In relation to long-term stability of these oleogels, the values of viscoelastic functions significantly increase during the first 7 days of ageing and then remain almost constant.

We report the selective formation of cyclohexenes with a tetrasubstituted double bond, the structural key element of megastigmanes. For this purpose the ZrCl4-mediated epoxide ring opening of epoxy-geranylacetone was employed. This approach provides a universal entry to the preparation of the members of the megastigmane family, which was exemplified in the asymmetric synthesis of tectoionol B.

This work deals with the design of lubricating greases formulations based on blends of mineral oil and recycled polypropylene from postconsumer waste, coming from films with inks. In particular, the influence of polymer concentration on the rheological, mechanical, and thermal properties of recycled polymer/oil blends was characterized. From the experimental results obtained, it can be deduced that the evolution of recycled polymer/mineral oil formulations on linear viscoelasticity functions with frequency is quite similar to that found for traditional lithium greases. It is observed that these blends form systems with enhanced “plateau” modulus, G, with respect to industrial standard lubricating greases, which could be represent an important advantage, from an economic and environmental point of view. However, the influence of temperature on linear viscoelasticity functions is more pronounced than that found for traditional greases. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

The titanocene-mediated cyclization of suitably functionalized acyclic C10 epoxy-polyprenes leads, with moderate stereoselectivity, to high yields of functionalized terpenic cyclopentanes with three contiguous stereogenic centers. These highly functionalized cyclopentanes are useful intermediates for the synthesis of several natural compounds that include this interesting subunit in their structure. Both the regioselectivity of the process leading to cyclopentanes and the stereoselectivity of the cyclization could be controlled by using malonyl derivatives or α,β-unsaturated nitriles as radical acceptors.

A simple approach to A-ring-γ-dioxygenated terpenoids is described which involves two key steps, namely, selenium-catalyzed selective allylic chlorination of polyprenoids and titanocene-mediated radical cyclization of epoxypolyprenes. We have applied this synthetic route to the first synthesis of the diterpene, (13E)-ent-labda-8(17),13-diene-3β,15,18-triol. A stereoselective approach to this synthesis is also described.

The first total synthesis of potent anti-inflammatory polypodanes (+)-myrrhanol A (1), (+)-myrrhanone A (2), (+)-myrrhanone B (3), and (+)-myrrhanol B (4) has been achieved. Key steps in our convergent, highly stereocontrolled route are a Ti(III)-mediated radical cyclization of a chiral monoepoxide to furnish a bicyclic synthon that combines stereospecifically with an acyclic vinyl iodide via an intermolecular B-alkyl Suzuki-Miyaura cross-coupling.

Covering: 1998 to 2008 The biosynthetic origin of most of triterpenes lies in cascade cyclizations and rearrangements of the acyclic precursors squalene (S) and 2,3-oxidosqualene (OS), processes leading to tetra- and pentacyclic triterpene skeleta. Apart from these, a number of triterpenoid structures derived from cyclization processes, that are different from those leading to tetra- and pentacyclic triterpenes, are also found in Nature. We have defined these processes as unusual cyclizations, and grouped them in three blocks, namely, incomplete cyclizations of the corresponding S-derived precursors, cyclizations of S or OS towards polycyclic triterpenes and subsequent cleavage of the preformed ring systems, and two independent cyclizations of the S- or OS-derived precursor. Apart from the molecules obtained from intact organisms, we will also consider the compounds obtained from in vitro cyclizations promoted by enzyme systems. After establishing which compounds could unambiguously be grouped under the term ‘unusually cyclized triterpenes’, this review moves on to the advances achieved in this kind of structure during the last ten years. These advances are presented in three parts. The first one presents the structure and biological properties of the unusual triterpenes reported in the last decade. The second part considers the main biosynthetic pathways which justify the formation of these triterpenes from their corresponding acyclic precursors. Finally, we look at the achievements made in different synthetic strategies directed at some of these molecules. One hundred and twenty-three references are cited.

Sulfanyl radicals trigger a tandem addition–cyclization protocol in linalool or citronelene derivatives for the efficient construction of the iridane monoterpene skeleton. Best results in yields and diastereoselectivity were obtained when phenylethylsulfanyl was used as radical initiator. We have proved the utility of this protocol with the enantiospecific synthesis of natural iridane dehydroiridomyrmecin starting from a (−)-linalyl acetate ester derivative in five steps with a 28% overall yield.

The transannular cyclization of epoxycaryophyllenes 2–7 catalyzed by TiIII has been investigated. This cyclization led to alcohols 8–15, all of them possessing a tricyclo[6.3.0.02,5]undecane skeleton. All of these compounds present pleasant aromatic properties. The cyclization takes place with high yields (> 80 %) and via the αα or ββ conformation of the intermediate radical I. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

The reaction of the Cp2TiCl complex with oxiranes leads to homolytic opening of the heterocycle with high regioselectivity. Although the resulting β-titanoxyl radical can evolve in different ways, when the epoxide reacting with Cp2TiCl possesses suitable unsaturated moieties such as olefins, triple bonds, carbonyls or nitriles in its structure, intramolecular addition of this β-titanoxyl radical to these unsaturated groups can take place, leading to a cyclization process. Structures containing from three- to seven-membered rings have been synthesized using either stoichiometric or catalytic quantities of titanocene. Although a number of applications for these titanium-mediated cyclization reactions have been reported in the synthesis of natural products and bioactive compounds such as antibiotic γ-lactones, lignans and β-lactams, we consider that the strategy involving the opening and ensuing cyclization of the monoepoxides of polyprenes, which resulted in the preparation of C10, C15, C20 and C30 terpenoids, including mono-, bi- and tricyclic natural products, deserves special mention. Attractive aspects of this reaction are good stereochemical control and the oxidative termination of the process, which leads regioselectively to exocyclic olefins. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

[reaction: see text] The Ti(III)-catalyzed reaction of a series of vinylepoxides leads, with regio- and E-diastereoselectivity control, to good-to-excellent yields of the corresponding homocoupling products. This homocoupling reaction, which involves a new C-C bond-forming method, takes place via a S(N)2' process between an allyltitanium species and the starting vinylepoxide. The process can be used for the rapid and efficient formation of highly valuable intermediates for organic synthesis, as well as new interesting homologues of natural products.

[reaction: see text] Titanocene chloride catalyzes the regioselective alpha,alpha'-homocoupling of terpenic allylic halides. This process has been employed in the short and effective synthesis of terpenoids such as beta-onoceradiene (1), beta-onocerin (2), and squalene (3). Evidence is presented for eta1-allyltitanium species being involved in the coupling.

Five new abietanes, three of them isolated as the corresponding acetate derivatives, i.e., 9α,13α-epidioxiabiet-8(14)-en-18-ol, 7α,18-diacetoxy, 9β,13β-epidioxiabiet-8(14)-ene, 7α,18-diacetoxyabiet-8(14)-en-13β-ol, 7α,18-diacetoxy-13β-methoxyabiet-8(14)-ene, and 13β-hydroxyabiet-8(14)-en-7-one, were isolated from the neutral part of the hexane extract of the cones of Cedrus atlantica collected in Middle Atlas, Morocco. The structures of these compounds were established by spectroscopic techniques, including 2D NMR spectra, and in the case of 1 , by chemical correlation. The cytotoxicity of these abietane diterpenoids was tested against five cell lines.

A detailed experimental and theoretical study corroborates that the reductive deoxygenation of activated (allylic or benzylic) alcohols with excess Ti(III) proceeds via an allyl(benzyl)-radical and allyl(benzyl)-Ti, which is protonated, regioselectively in the case of allylic derivatives. The H atom of the newly formed C–H bond in the product originates from the –OH group of the starting material. The deoxygenation of lithium alkoxides or alcohols by using 1.0 mol of Ti(III) leads to the corresponding dimerization products in good yields. An excellent agreement with the experimental data was obtained by using a reaction kinetics simulator to discriminate between competing reactions.

Apocarotenoids are metabolites originated by degradation of carotenes through the loss of carbon atoms placed at the side chain of their structure as consequence of oxydative reactions. We present here the first review of apocarotenoids in the fungi mucorales Phycomyces blakesleeanus, Blakeslea trispora and Mucor mucedo. This review is divided into two parts: the first one presents their structures and sources, whereas the second part is dedicated to their chemical synthesis.

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.

The anodic oxidation of mercury in the presence of hydrogen peroxide in differential pulse voltammetry (DPV) was used to determine the antioxidant (AO) character of radical scavengers. Hydroperoxide radical is formed at the potentials of the oxidation peak on mercury electrodes, such radical reacting with the antioxidants in different extension. The parameter C10 (antioxidant concentration at which the peak area decreases by 10%) is used to measure the scavenging activity of the individual antioxidants. To establish the scavenging activity of antioxidant mixtures as a whole, the parameter, μ10 as the reverse of V10, V10 being the volume necessary to decrease the peak area in DPV by 10%, was selected. Higher μ10 values correspond to higher scavenging activity. The studies have been extended to aqueous extracts of some species. The results may be useful in explaining the effect of spices in vitro and in vivo studies.

The first total synthesis of the natural apocarotenoids (+)-apotrisporin E (1) and (+)-apotrientriols A and B (2–3) has been accomplished. The structure, relative stereochemistry and the assignation of the absolute configuration have been confirmed. This is a fast and easy access to this family of natural products whose key steps are a diastereoselective cyclization and a HWE olefination to attach the dienic side chain. This work also opens the door to the synthesis of other apocarotenoids such as trisporols and trisporic acids.