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Biogenic volatile organic compounds (bVOCs), synthesised by plants, are important mediators of ecological interactions that can also undergo a series of reactions in the atmosphere. Ground-level ozone is a secondary pollutant generated through sunlight-driven reactions between nitrogen oxides (NOx) and VOCs. Its levels have increased since the industrial revolution and reactions involving ozone drive many chemical processes in the troposphere. While ozone precursors often originate in urban areas, winds may carry these hundreds of kilometres, causing ozone formation to also occur in less populated rural regions. Under elevated ozone conditions, ozonolysis of bVOCs can result in quantitative and qualitative changes in the gas phase, reducing the concentrations of certain bVOCs and resulting in the formation of other compounds. Such changes can result in disruption of bVOC-mediated behavioural or ecological interactions. Through a series of gas-phase experiments using Gas Chromatography Mass Spectrometry (GC-MS) and Proton Transfer Reaction Mass Spectrometry (PTR-MS), we investigated the products and their yields from the ozonolysis of a range of ubiquitous bVOCs, which were selected because of their importance in mediating ecological interactions such as pollinator and natural enemy attraction and plant-to-plant communication, namely: (E)-β-ocimene, isomers of α and β-farnesene, α-terpinene and 6-methyl-5-hepten-2-one. New products from the ozonolysis of these compounds were identified, and the formation of these compounds is consistent with terpene-ozone oxidation mechanisms. We present the degradation mechanism of our model bVOCs and identify their reaction products. We discuss the potential ecological implications of the degradation of each bVOC and of the formation of reaction products. [ABSTRACT FROM AUTHOR]

This document provides an overview of dealkenylative functionalization, a chemical process that involves breaking alkenyl C(sp3)-C(sp2) bonds. The method utilizes iron(II)-mediated reductions of alkyl hydroperoxides to generate alkyl radicals that can be trapped by radical acceptors. The article discusses the historical development of peroxide decomposition chemistry and radical functionalization methods, as well as the motivation behind pursuing dealkenylation. The document also highlights the successful application of hydrodealkenylation in the synthesis of natural products, emphasizing its strategic and sustainable benefits. The authors acknowledge the traditional territory of the Gabrielino/Tongva peoples. [Extracted from the article]

Essential oils are composed of terpenes, some of which have properties related to healing. Bursera schlechtendalii essential oil (BSEO) is used to heal superficial wounds. However, there have been no studies verifying this property. The objectives of this study were to evaluate the healing activity of BSEO in a murine model and to propose the roles of its chemical components in this process. Healing activity was evaluated by an incision model, histological analysis was performed, and tensile strength and antibacterial activity were measured. The chemical composition of BSEO was determined by gas chromatography coupled with mass spectrometry (GC–MS), and the mechanisms of action of each chemical component during the phases of the healing process were proposed. In addition, acute dermal toxicity was evaluated. BSEO showed better wound closure at the macroscopic, histological, and tensile strength levels compared to controls and had an antibacterial effect. The major compound in BSEO was α-phellandrene. However, most of the monoterpenes identified in BSEO were in agreement with information found in the literature, so the possibility of synergy between the chemical components and their different targets in the healing process was schematically proposed. BSEO was shown to be safe in the dermal toxicity evaluation. [ABSTRACT FROM AUTHOR]

The production and use of terpene-based fuels represents a renewable source of energy in the transportation sector, especially in the aviation sector. The literature on the conversion of terpenes into valuable compounds is not new but has been based on the production of products for cosmetics and pharmaceutics. Several established chemical routes are also a way to develop drop-in fuels. The present work explores all the main chemical processes that can transform terpenes into more valuable fuels or additives, focusing on the use of heterogeneous catalysis, catalyst type, operating conditions, and reaction performance. α-pinene is the most studied catalyst, since it is the main component of turpentine. Isomerization is the most frequently applied chemical pathway used to enhance fuel properties, and a wide group of heterogeneous catalysts have been reported, with sulphonic acid resin catalysts, transition metals, alumina, and silicates being the most used. This work also explores the current production and commercialization of terpenes, as well as the challenges for their use as fuels at a commercial scale. The future challenge is to discover new catalysts or to improve the performance of the current products and reduce production costs. The feasibility of the production and commercialization of terpene-derived fuels is also linked to oil prices. [ABSTRACT FROM AUTHOR]

Parthenium hysterophorus possesses certain allelochemicals responsible for their medicinal effects. The presence of oils, polyphenols, alkaloids, terpenes, pseudoguaianolides, and histamines in P. hysterophorus has been shown to exhibit medicinal properties. However, the systematic biomedical properties of this plant are still unexplored. The extracts of leaves, stem, and flower of P. hysterophorus, both at low and high temperatures (equivalent to boiling points of different solvents) were prepared. The extracts prepared in hexane, ethylacetate, methanol, and water were analyzed spectrophotometrically and colorimetrically and resolved on TLC for the presence of phytochemicals. The analyses of the free radical quenching potential of plant extracts were done by DPPH assay. The total antioxidant capacity was determined by phosphomolybdate assay and the ferric reducing antioxidant power (FRAP) assay was used to determine the reduction potential of the extracts. The spectrophotometric and qualitative analysis of plant extracts demonstrated the presence of alkaloids, terpenoids, carbohydrates, and cardiac glycosides. The occurrence of more than one Rf values for extracts determined by TLC indicated the presence of more than one phytochemical compound. The P. hysterophorus extracts contained strong antioxidant activity. These extracts exhibited strong antimicrobial activity against Staphylococcus epidermis, Salmonela typhi, Neisseria gonococci or gonococci, Citrobacter, and Shigella flexineri. The evaluation of the antimicrobial potential of P. hysterophorus extracts was done by the disc diffusion method. These extracts also showed significant inhibition against HIV-1 RT activity. The anti-HIV-1 RT activity was done using Roche Kit. The P. hysterophorus extracts displayed the presence of many phytochemicals with strong antioxidant, antimicrobial, and anti-HIV-1 RT properties. [ABSTRACT FROM AUTHOR]

Enzyme catalysis has emerged as a key technology for developing efficient, sustainable processes in the chemical, biotechnological and pharmaceutical industries. Plants provide large and diverse pools of biosynthetic enzymes that facilitate complex reactions, such as the formation of intricate terpene carbon skeletons, with exquisite specificity. High‐resolution structural analysis of these enzymes is crucial in order to understand their mechanisms and modulate their properties by targeted engineering. Although cryo‐electron microscopy (cryoEM) has revolutionized structural biology, its applicability to high‐resolution structural analysis of comparatively small enzymes has so far been largely unexplored. Here, it is shown that cryoEM can reveal the structures of plant borneol dehydrogenases of ∼120 kDa at or below 2 Å resolution, paving the way for the rapid development of new biocatalysts that can provide access to bioactive terpenes and terpenoids. [ABSTRACT FROM AUTHOR]

Cronartium pini causes economic losses especially on Scots pine in northern Europe. Scots pine reacts to rust infection by resin flow. The chemicals enriched in wood after Cronartium infection have not been investigated before. We investigated resin acids and mono‐ and sesquiterpenes produced in Cronartium‐infected wood. Cronartium‐infected wood was extracted with acetone, and the extractives were analysed by GC‐mass spectrometry (GC‐MS) and compared to those from control wood. Among resin acids, abietic acid, levopimaric acid, palustric acid, dehydroabietic acid and neoabietic acid were the richest (32–68 mg/g) in Cronartium‐infected wood. Among monoterpenes, concentration of α‐pinene was the highest (49 mg/g) in Cronartium‐infected wood. Concentrations of all monoterpenes and resin acids and most sesquiterpenes were significantly higher (1.3‐ to 108‐fold) in Cronartium‐infected wood compared to control wood. In the control wood, the extractive content was greater (1.1‐ to 14‐fold) than in the literature suggesting that the chemical processes were strongly affected by the rust. The results suggest that terpenes and resin acids are produced by the host to protect it from Cronartium rust. [ABSTRACT FROM AUTHOR]

Covering: 2011–2017 Radical cyclizations have a rich history in organic chemistry and have been particularly generous to the field of natural product synthesis. Owing to their ability to operate in highly congested molecular quarters, and with significant functional group compatibility, these transformations have enabled the synthesis of numerous polycyclic terpenoid natural products over the past several decades. Moreover, when programmed accordingly into a synthetic plan, radical cascade processes can be used to rapidly assemble molecular complexity, much in the same way nature rapidly constructs terpene frameworks through cationic cyclization pathways. This review highlights recent total syntheses of complex terpenoids (from 2011–2017) employing C–C bond-forming radical cascade sequences. [ABSTRACT FROM AUTHOR]

A phytochemical investigation onEuphorbia alatavicaBoiss resulted in the isolation of nine compounds, including two new ones, alatavolide and alatavoic acid(1–2). Chemical structures of these compounds were established on the basis of 1D, 2D NMR, and HR-MS techniques, and by comparison with data reported in the literature. Compounds1,2,4,6,8,and9were screened for cytotoxicity using the MTT assay. Among these compounds, the new compound2showed moderate cytotoxicity against Hela, MCF-7 and A549 cell lines (IC50values of 16.4 ± 3.2, 14.5 ± 2.8, 22.3 ± 3.1 μM, respectively), while the known compound8exhibited the most potent cytotoxicity with the IC50values of 6.5 ± 3.1, 1.9 ± 0.9, 8.6 ± 3.5 μM, respectively. [ABSTRACT FROM AUTHOR]

The structurally intriguing terpenes pallambins C and D have been assembled in only 11 steps from a cheap commodity chemical: furfuryl alcohol. This synthesis, which features a redox-economic approach free of protecting-group manipulations, assembles all four-ring systems via a sequential cyclization strategy. Of these fourring constructing operations, two are classical (Robinson annulation and Mukaiyama aldol) and two are newly devised. During the course of this work a method for the difunctionalization of enol ethers was developed, and the scope of this transformation was explored. [ABSTRACT FROM AUTHOR]

3-Carene, α-pinene, and limonene α-(dimethylamino)oximes were converted to glycidyl ethers at the oxime hydroxyl. The compounds obtained were involved in the reactions with amines, imidazole, as well as with anions of these dimethylamino oximes. The glycidyl ether epoxide ring opening by amines under microwave irradiation conditions proceeds considerably faster than upon convection heating. [ABSTRACT FROM AUTHOR]

The present paper describes a total synthesis of racemic β-chamigrene (1), a sesquiterpene with a spiro[5.5]undecane carbon framework. Compared with previously reported β-chamigrene syntheses, we were able to reduce the total number of reaction steps, which also resulted in a significant improvement of the overall yield. The commercially available ketone 6-methylhept-5-en-2-one was transformed by known simple procedures into 3,3-dimethyl-2-methylenecyclohexanone. This reacted with isoprene by a Diels-Alder reaction to give a spiro ketone. An olefination reaction on this compound gave the target molecule. [ABSTRACT FROM AUTHOR]

[Display omitted] • Natural rubber can be used as a source isoprenoid-related compounds; • Biofragmentation can lead the formation of smaller and more defined products. • A wide range of molecular weights is obtained from chemical fragmentation approaches. • Cross-metathesis can introduce other chemical functions than aldehyde and keto groups. • Liquid-liquid extractions and precipitations are the most employed methods of purification. Natural rubber (NR) 1 1 NR: natural rubber is a biopolymer mainly composed of isoprene units linked to form double bonds with cis configuration. After the vulcanization process, NR is widely employed not only into fabrication of tyres, but also for many other products. Due to the forthcoming depletion of fossil fuel sources and to the growing tyre waste issue, NR is considered as a potential source of fine chemicals. Isoprene oligomers can be obtained either through bio- or chemical fragmentation processes. Although several microorganisms are able to fragment the rubber chains were isolated, the use of isolated enzymes proved to be more efficient regarding the number of compounds produced. Among the chemical methodologies for NR depolymerization, oxidative cleavages and cross metathesis are the most commonly used procedures to obtain isoprene oligomers. After enzymatically catalyzed fragmentations through oxidative cleavage possesses, the obtained oligomers have aldehyde and ketone end chain groups. A wide range of terminal groups can be obtained with metathesis reactions. We also point to the main procedures to recover isoprene oligomers and highlight some applications and perspectives. [ABSTRACT FROM AUTHOR]

In order to produce petroleum alternatives from biomass, a significant amount of research has been focused on oils from microalgae due to their origin, which would not affect food availability. Nanoporous hybrid catalysts composed of ns Al2O3 and zeolites have been proven to be very useful compared to traditional catalysts in hydrotreating (HT), hydrocracking (HC), and catalytic cracking (CC) of large molecules. To evaluate the reaction scheme and products from model isoprenoid compounds of microalgae oil, nanoporous hybrid catalyst technologies (CC: ns Al2O3/H-USY and ns Al2O3/H-GaAlMFI; HC: [Ni-Mo/γ-Al2O3]/ns Al2O3/H-beta) were studied. The major product from CC on ns Al2O3/H-USY was highly aromatic gasoline, while the product from HC was half-isoparaffinic/olefinic kerosene. Although more than 50wt% of the products from HT/CC on the USY catalyst was liquefied petroleum gas due to overcracking, the product from HT/CC on the MFI catalyst was high-octane-number gasoline. Delightfully, the product from HT/HC was kerosene and its average number was 11, with more than 80wt% being isoparaffinic. As a result, it was demonstrated that hydrotreating may convert isoprenoid oil from microalgae over nanoporous hybrid catalysts into a variety of products. [ABSTRACT FROM AUTHOR]

Abstract: Enantiospecific total synthesis of two epimeric sesquiterpenes 11-hydroxyguaiadienes has been accomplished starting from the readily available monoterpene (R)-limonene, which confirmed the structure and absolute configuration of the natural products. [ABSTRACT FROM AUTHOR]

Abstract: Aromatisation of olive oil is a new trend in the Mediterranean area, both for sensory and for nutritional improvement. This work presents the development of a green enrichment of an olive oil with basil. In fact instead of a solvent extraction of the aromas, purify them and add them to the olive oil or instead of doing steam distillation prior to add the essential oil into the olive oil, basil leaves were directly put into the olive oil. Ultrasounds were then applied to the mixture in order to accelerate diffusion of the basil volatile compounds into the olive oil. The processing time is reduced from hours or days to few minutes when comparing traditional maceration and ultrasound assisted aromatisation. GC/MS chromatographs have similar profiles between macerated and ultrasounds assisted macerated oils. Concentration of linalool and eugenol were calculated into the aromatised oils and used as indicators of the aromatisation. [Copyright &y& Elsevier]

Twenty marine-engine lubricants from five Japanese oil companies were discriminated on the basis on a hopane analysis using a gas chromatograph−mass spectrometer (GC−MS). The hopane ratios of 18α-22,29,30-trisnorneohopane (1) to 17α-22,29,30-trisnorhopane (2) and of 17α-21β(H)-norhopane (3) to 17α-21β(H)-hopane (5) were determined. Each lubricant can be discriminated by combining the figures represented by the 1to 2and 3to 5ratios and principal component analysis from 1through (22R)-17α-21β(H)-29-pentakishomohopane (15). Oleanane (4), one of the biomarkers inherent in the crude oils from Southeast Asia, has been detected in the lubricants of eight out of 20 types, and 4represents a significant feature for the discrimination. The discrimination of the lubricants in the spilled oils was also investigated. [ABSTRACT FROM AUTHOR]

Rabdoternin A is a natural diterpenoid isolated from Rabdosia rubescen and its crystal structure was determined by X-ray single crystal diffraction. The compound compactly packs in an orthorhombic unit cell in the P222 space group with unit cell dimensions a = 7.9200(10) Å, b = 11.2411(14) Å, c = 20.474(2) Å, V = 1822.8(4) Å and Z = 4. Two intermolecular hydrogen bonds assemble the title compound into infinite two-dimensional networks along (001) plane. Graphical Abstract: Rabdoternin A is a natural diterpenoid isolated from Rabdosia rubescen and its crystal structure was determined by X-ray single crystal diffraction. The compound is built up from five-six-membered rings and one-five-membered ring, intermolecular hydrogen bonds assemble the title compound into infinite two-dimensional networks along (001) plane.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: Betulinic acid, a triterpenoid found in many plant species, has attracted attention due to its important physiological and pharmacological properties. In order to obtain betulinic acid, betulin was submitted to transformation with the selected microorganisms. Betulin biotransformation was carried out with the filamentous fungi Armillaria luteo-virens Sacc QH (ALVS), Aspergillus foetidus ZU-G1 (AF) and Aspergillus oryzae (AO) under seven kinds of transformation condition. As a result of transformation of betulin, A. luteo-virens Sacc QH was the best biocatalyst to produce betulinic acid under the designed conditions. Transformation caused by pre-cultured fungal mycelia, a process designated as G2, was favorable condition for betulin biotransformation as the productivity of betulinic acid was evaluated (>20%). M1 and M2 systems, where the betulin substrate was micro-emulsified in mixtures of Tween 80 and organic solvents, were potential substitutes for G2. The possible pathway of betulin transformation is postulated in this work. The use of fungi and transformation mode described in current work are viable procedures for producing betulinic acid, which is of most importance to replace chemical synthesis ways. [Copyright &y& Elsevier]

Abstract: Electroepoxidation of synthetic alkenes (styrene, trans-stilbene and trans-β-methylstyrene) and of some natural terpenes (limonene, terpinolene, geraniol, α-terpinene, γ-terpinene and α-terpineol) mediated by sodium bromide was performed in MeCN:H2O (4:1) at platinum electrodes. The indirect electrochemical oxidation of the olefins led to the corresponding epoxides in yields ranging from 23% to 79%. [Copyright &y& Elsevier]

A total synthesis of (±)-cis-5-hydroxycalamenene 1 has been achieved from tetralone 5, which in turn was prepared from 5-methoxy-α-tetralone 3. Grignard reaction of compound 5 with isopropylmagnesium chloride, followed by dehydration and aromatization, provided the substituted naphthalene 7 whose conversion to (±)-cis-5-hydroxycalamenene 1 was accomplished by demethylation, formylation, and hydrogenation. [ABSTRACT FROM AUTHOR]

A general preparation method of the all-(E)-polyprenols 12 has been developed from readily available geranyl sulfone by the chain-extension process utilizing the C5 unit 5 and the chain-termination process utilizing the C5 unit 10 together with the chemoselective reductive desulfonylation. The polyprenols 12 were converted to compounds 3 containing two consecutive prenyl sulfone moieties at the tail end, which underwent the controlled electrophilic cyclization only at the carbon-carbon double bonds that were remote from the flat and rigid benzenesulfonyl groups. [ABSTRACT FROM AUTHOR]

The review discusses recent advances in the field of acid-catalyzed intra- and intermolecular transformations of pinane terpenoids and their oxygen-containing derivatives. [ABSTRACT FROM AUTHOR]

Two new triterpenoid saponins, named cernuaside C and D, have been isolated from Pulsatilla cernua (Thunb.) Bercht. et Opiz. The structures of the two new triterpenoid saponins were elucidated as 3-O-β-D-xylopyranosyl(1 → 2)-[α-L-rhamnopyranosyl(1 → 3)]-α-L-arabinopyranosyl oleanolic acid 28-α-L-rhamnopyranosyl(1 → 4)-β-D-glucopyranosyl(1 → 6)-β-D-glucopyranoside. (1) and 3-O-α-L-arabinopyranosyl (1 → 3)-α-L-rhamnopyranosyl(1 → 2)-α-L-arabinopyranosyl oleanolic acid 28-O-β-D-glucopyranoside (2) by 1D, 2D-NMR techniques, ESI-MS analysis as well as chemical methods. [ABSTRACT FROM AUTHOR]

Abstract: Turpentine, an important source of terpenes, is composed mainly of α- and β-pinene. It is possible to pyrolyze β-pinene to form myrcene, which is used as an intermediate for the production of various terpenic alcohols and chemical aromas, as well as vitamins A and E. In the current work we develop a theoretical equilibrium model of the main synthesis reactions that have been described in the literature plus postulated decomposition reactions. The model predicts that 93.5% yields of myrcene from β-pinene would be possible whereas the highest reported yield is 85%. In order to investigate the less than theoretical yields, we investigated the decomposition of myrcene experimentally. The various degradation products that appeared were consistent with a degradation mechanism involving breakage next to conjugated double bonds, producing an alkyl radical. Decomposition of myrcene by this route would form 1,3-butadiene (C4H6) and 4-methyl-1,3-pentadiene (C6H10), which then further decompose into various other products. These results contribute to a better understanding of the production of myrcene by pyrolysis of β-pinene and could form the basis for optimization of product yields. [Copyright &y& Elsevier]

The article discusses the catalytic reaction that help convert carbohydrates, vegetable oils, animal fats, and terpenes into valuable chemicals and fine chemicals. It focuses on chemical routes through heterogeneous catalysis and to describing catalytic processes that is not harmful to the environment as an alternative to the old processes.

The first total synthesis of an (E)-cladiellin diterpene, (-)-cladiella-6,11-diene-3-ol (1), was accomplished featuring an intramolecular amide enolate alkylation-intramolecular Diels-Alder strategy. In addition, a highly stereo-, regio-, and chemoselective synthetic strategy for other members of the cladiellin diterpenes such as (+)-polyanthellin A (2), (-)-cladiell-11-ene-3,6,7-triol (3), and (-)-deacetoxyalcyonin acetate (4) was developed utilizing the synthetic (E)-cladiellin 1 as a common intermediate by taking advantage of the unique chemical properties of its C(6)-(E)-oxatricyclic skeleton. [ABSTRACT FROM AUTHOR]

Abstract: Starting with larixol, syntheses of furan and 1,4-enedial labdane-type diterpenes are presented, which has enabled a preparation of hedychenone (20% yield). [Copyright &y& Elsevier]

Three types of new Euphorbia diterpene pseudo-alkaloids possessing 5/6/7/3 (1), 5/6/6/4 (2–5), and 5/7/7/4 (6–7) fused ring skeletons were obtained through an unexpected BF 3 ·Et 2 O/CH 3 CN-mediated structural conversion and amination of lathyrane diterpene (Euphorbia factor L 1), in which the solution acetonitrile had been introduced into the Euphorbia diterpene as a nitrogen source and tandem amination/oxirane-opening (cyclopropane-opening)/oxa-Michael addition reaction was involved in the conversion. The structures of new Euphorbia diterpene pseudo-alkaloids were elucidated by a combination of spectroscopic data and single crystal X-ray diffraction analysis. The basic skeletons of Euphorbia diterpene pseudo-alkaloids 1 and 2 – 5 could fall into the structural types of euphoractine B and euphoractine A diterpenes, respectively, suggesting the possible biogenetic pathway relationship between lathyrane diterpene with euphoractines A and B types diterpenes. Pseudo-alkaloids 1 – 7 did not show any potential cytotoxicity against several tumor cell lines. Unlabelled Image [ABSTRACT FROM AUTHOR]

The article reports on the synthesis of tenuifolin through intramolecular nicholas reaction.

This paper presents results obtained from the thermoisomerization of essential oils (trementine and pimenta) in the presence of Lewis solid acids. It also reports, in a comparative way, the manisfestation of topical applications of thermochemically treated essential oils used as insecticides or fungistatics. Even if the efficiency degree of trementine oil thermochemically treated (limonene enriched) is inferior to the synthetic insecticides, its action would be more effective and economic by applying appropiate mixtures. All the products used are natural ones, bio-degradable, non-contaminating, and can be easily handled. [ABSTRACT FROM AUTHOR]

Review: 102 refs. [ABSTRACT FROM AUTHOR]

Two new compounds are prepared starting from 3-oxo-camphorsulphonylimine (I). [ABSTRACT FROM AUTHOR]

isolation, structure elucidation and cytotoxicity of ent-abierubesins A-E (I)-(IV) and new ent-kauranoids, hubeirubesins A (V) and B (VI) [ABSTRACT FROM AUTHOR]

isolation and structure elucidation [ABSTRACT FROM AUTHOR]

The key step of this synthesis of the title compounds (respectively their enantiomers) is an organocatalyzed asymmetric [4 + 3] cycloaddition yielding key intermediate (V). [ABSTRACT FROM AUTHOR]