Search

The ruthenium catalysed cross-metathesis of terpenoids with methyl acrylate and methyl methacrylate was used to prepare new terpenoids and to improve, to a large extent, the synthesis of known terpenoids. In particular, the cross-metathesis of mono-unsaturated terpenoids was very efficient whereas the transformation of terpenoids incorporating two double bonds was more difficult due to side reactions. The cross-metathesis reactions were carried out under environmentally friendly conditions either in dimethyl carbonate or under solvent-free conditions. [ABSTRACT FROM AUTHOR]

Three upper rim site lipophilic calix[4]arenes 1–3featuring different para-alkanoyl substituents at the phenolic moieties, i.e.n-hexanoyl, n-octanoyl and 3-cyclohexylpropanoyl groups, are reported to complex, aside from the common solvent molecule n-butanol, different keto and hydroxylic terpene guest molecules such as (−)-menthone, (−)-menthol or (+)-carvone in the solid state. Although for all six inclusion compounds described here, a strict 1 : 1 host : guest stoichiometry is observed, complementary size and polarity relationships between the cone shaped calixarene cavity and the guest molecule emerge from single crystal X-ray structural study. Dependent on the structure of the guest molecule, the calixarenes are arranged in a head-to-head or head-to-tail orientation in the crystalline packing, giving rise to capsular or otherwise deeply enclosed inclusion mode of the guest molecules, respectively. Furthermore, the O-acyl atoms of the calixarenes were found to be directly involved in host–guest interaction. In order to estimate the degree of isostructurality of the host frameworks and to examine the influence of the guest molecules on the solid-state conformation of these calixarene molecules, isostructurality comparison, cell similarity and molecular isometricity calculations were carried out revealing a rare case of supramolecular morphotropism for the pair of (−)-menthone and (−)-menthol inclusions of the n-hexanoyl substituted calixarene. Structure–inclusion property relationship was examined by QMB measurements of thin layers of the calixarenes. Vapor studies with different terpenes and common organic solvents show an increased affinity towards guest molecules with polar functionalities, whereas small solvent molecules like acetone are bound considerably better than the more bulky terpene molecules. [ABSTRACT FROM AUTHOR]

Hydrophobic deep eutectic solvents were investigated for tetracycline microextraction. It was found that a deep eutectic solvent consisting of thymol and octanoic acid provided a synergistic effect on tetracycline extraction. In this paper, a novel liquid–liquid microextraction procedure for the HPLC-DAD determination of tetracyclines in milk samples was proposed. [ABSTRACT FROM AUTHOR]

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as kadsuraol A from Kadsura longipedunculata. [ABSTRACT FROM AUTHOR]

A personal selection of 32 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as macrophilone A from Macrorhynchia philippina. [ABSTRACT FROM AUTHOR]

Covering: 1966 up to the end of 2013 The paper reviews the known examples of cyclic terpenoids produced from open chain polyenic precursors by an “unusual” biosynthetic pathway, involving selective electrophilic attack on an internal double bond followed by cyclization. The resulting compounds possess cyclic backbones with pendant terminal prenyl groups. Synthetic approaches applied for the synthesis of such specifically functionalized compounds are also discussed, as well as biological activity of reported representatives. [ABSTRACT FROM AUTHOR]

Fresh Mentha haplocalyxis a well known traditional Chinese medicinal material (CMM) used in both China and America. This paper reports analysis of the volatile components of fresh Mentha haplocalyxby comprehensive two-dimensional gas chromatography (GCxGC) and high-resolution time-of-flight mass spectrometry (HR-TOF-MS), a combination that provides almost complete chemical separation with elemental composition determination of analytes. 163 ketones and terpenes, including menthol and menthone, were tentatively identified, including enantiomers. This study suggests that GCxGCxHR-TOF-MS is suitable for routine identification of target compounds and enantiomers in CMM. [ABSTRACT FROM AUTHOR]

A personal selection of 27 recent papers is presented covering various aspects of current developments in bioorganic chemistry and novel natural products such as dibelamcandal A from Belamcanda chinensis. [ABSTRACT FROM AUTHOR]