Pea aphid odorant-binding protein ApisOBP6 discriminates between aphid sex pheromone components, aphid alarm pheromone and a host plant volatile.

Olfactory perception of pheromones in insects involves odorant-binding proteins (OBPs), relatively small proteins (ca.110-240 amino acid residues) that can bind reversibly to behaviourally active olfactory ligands. In this study, we investigated the binding in silico and in vitro of the aphid sex pheromone components (1R,4aS,7S,7aR)-nepetalactol and (4aS,7S,7aR)-nepetalactone and the aphid alarm pheromone (E)-β-farnesene by OBPs from the pea aphid, Acyrthosiphon pisum.

Evaluation of two terpene-derived polymers as consolidants for archaeological wood.

The evaluation of two terpene-derived polymers, termed TPA6 and TPA7, as possible consolidants for archaeological wood was carried out. The overall objective of this work was to expand the non-aqueous treatment toolkit which is available for the conservation of the highly degraded Oseberg collection. The wood artefacts which were found on the Oseberg ship were treated with alum in the early twentieth century, leading to the formation of sulfuric acid and to the precarious state that they are in today.

Predictive Molecular Design and Structure-Property Validation of Novel Terpene-Based, Sustainably Sourced Bacterial Biofilm-Resistant Materials.

Presented in this work is the use of a molecular descriptor, termed the α parameter, to aid in the design of a series of novel, terpene-based, and sustainable polymers that were resistant to biofilm formation by the model bacterial pathogen . To achieve this, the potential of a range of recently reported, terpene-derived monomers to deliver biofilm resistance when polymerized was both predicted and ranked by the application of the α parameter to key features in their molecular structures. These monomers were derived from commercially available terpenes (, α-pinene, β-pinene, and carvone), and the prediction of the biofilm resistance properties of the resultant novel (meth)acrylate polymers was confirmed using a combination of high-throughput polymerization screening (in a microarray format) and testing.

Comparative hydrodynamic characterisation of two hydroxylated polymers based on α-pinene- or oleic acid-derived monomers for potential use as archaeological consolidants.

The Oseberg Viking ship burial is one of the most extensive collections of Viking wooden artefacts ever excavated in Norway. In the early twentieth century, many of these artefacts were treated with alum in order to preserve them, inadvertently leading to their current degraded state. It is therefore crucial to develop new bioinspired polymers which could be used to conserve these artefacts and prevent further disintegration.

Comparative Hydrodynamic Study on Non-Aqueous Soluble Archaeological Wood Consolidants: Butvar B-98 and PDMS-OH Siloxanes.

Butvar B-98 and PDMS-OH both have a demonstrable ability as consolidants for archaeological wood. This makes them both potential treatment options for the Oseberg collection, which is one of the most important archaeological finds from the Viking era. Both Butvar B-98 and PDMS-OH are soluble in organic solvents, offering a useful alternative to aqueous-based consolidants.

Iridoid Sex Pheromone Biosynthesis in Aphids Mimics Iridoid-Producing Plants.

Biosynthesis of (1R,4aS,7S,7aR)-nepetalactol (1) and (4aS,7S,7aR)-nepetalactone (2) in plants involves iridoid synthase (ISY), an atypical reductive cyclase that catalyses the reduction of 8-oxogeranial into the reactive enol of (S)-8-oxocitronellal, and cyclization of this enol intermediate, either non-enzymatically or by a nepetalactol-related short chain dehydrogenase enzyme (NEPS) that yields the nepetalactols. In this study, we investigated the biosynthesis in vivo of 1 and 2 in the pea aphid, Acyrthosiphon pisum, using a library of isotopically-labelled monoterpenoids as molecular probes. Topical application of deuterium-labelled probes synthesized from geraniol and nerol resulted in production of H -lactol 1 and H -lactone 2.

Terpene polyacrylate TPA5 shows favorable molecular hydrodynamic properties as a potential bioinspired archaeological wood consolidant.

There is currently a pressing need for the development of novel bioinspired consolidants for waterlogged, archaeological wood. Bioinspired materials possess many advantages, such as biocompatibility and sustainability, which makes them ideal to use in this capacity. Based on this, a polyhydroxylated monomer was synthesised from α-pinene, a sustainable terpene feedstock derived from pine trees, and used to prepare a low molar mass polymer TPA5 through free radical polymerisation.

Tert-butyldimethylsilyl chitosan synthesis and characterization by analytical ultracentrifugation, for archaeological wood conservation.

The Oseberg ship is one of the most important archaeological testimonies of the Vikings. After excavation in 1904, the wooden gravegoods were conserved using alum salts. This resulted in extreme degradation of a number of the objects a hundred years later through acid depolymerisation of cellulose and lignin.

Synthetic approaches and applications of sulfonimidates.

This review article explores the synthesis of the organosulfur(vi) species named sulfonimidates, focusing on their synthesis from sulfur(ii), sulfur(iv) and sulfur(vi) reagents, and investigates their recent resurgeance in interest as intermediates to access other important organosulfur compounds. Sulfonimidates have been utilized as precursors for polymers, sulfoximine and sulfonimidamide drug candidates and as alkyl transfer reagents.

General Method for the Asymmetric Synthesis of N-H Sulfoximines via C-S Bond Formation.

A versatile method for the synthesis of enantioenriched N-H sulfoximines is reported. The approach stems from the organomagnesium-mediated ring opening of novel cyclic sulfonimidate templates. The reactions proceed in high yield and with excellent stereofidelity with alkyl, aryl, and heteroaryl Grignard reagents.

Epoxy-amine oligomers from terpenes with applications in synergistic antifungal treatments.

A bis-epoxide monomer was synthesised in two steps from (R)-carvone, a terpenoid renewable feedstock derived from spearmint oil, and used to prepare β-aminoalcohol oligomers in polyaddition reactions with bis-amines without requiring solvent or catalyst. A sub-set of the resultant materials were readily water soluble and were investigated for antifungal activity in combination with the fungicide iodopropynyl-butylcarbamate (IPBC) or the antifungal drug amphotericin B. The oligo-(β-aminoalcohol)s alone were inactive against Trichoderma virens and Candida albicans but in combination with IPBC and amphotericin B demonstrated synergistic growth-inhibition of both fungi.

Sulfonimidates: Useful Synthetic Intermediates for Sulfoximine Synthesis via C-S Bond Formation.

Medicinally relevant sulfoximines are accessed from C-S coupling of sulfonimidates and commercially available organomagnesium reagents. Sulfonimidates are conveniently synthesized by oxidative alkoxylation of readily available sulfinamides. This constitutes a general C-S coupling approach for the synthesis of sulfoximines.

Asymmetric Synthesis of Pyrrolidine-Containing Chemical Scaffolds via Tsuji-Trost Allylation of N-tert-Butanesulfinyl Imines.

A simple and efficient asymmetric synthesis of novel sp -rich pyrrolidine chemical scaffolds over five steps starting from simple ketones is described. Key steps involve the use of tert-butanesulfinamide as a chiral auxiliary to perform an asymmetric Tsuji-Trost allylation, with subsequent cross-metathesis with an acrylate ester and reduction of the sulfinimine/cyclisation of the resulting amine giving the pyrrolidine scaffolds in high yields and diastereoselectivites. By removing the chiral auxiliary and functionalising the ester group, the resulting scaffold core can be further derivatised.

Expedient synthesis of an atypical oxazolidinone compound library.

In order to address the current downturn in the drug discovery pipeline, initiatives are being undertaken to synthesise screening libraries of sp-rich, low molecular weight compounds. As part of the European Lead Factory initiative, the synthesis and derivatisation of a simple hexahydrooxazolo[5,4-c]pyridin-2(1H)-one bicyclic carbamate has been achieved. The synthetic route employed involved a telescoped hetero-Diels-Alder/[2,3]-sigmatropic rearrangement/cyclisation sequence to deliver the desired core scaffold containing two points for further diversification.

Versatile C(sp(2) )-C(sp(3) ) Ligand Couplings of Sulfoxides for the Enantioselective Synthesis of Diarylalkanes.

The reaction of chiral (hetero)aryl benzyl sulfoxides with Grignard reagents affords enantiomerically pure diarylalkanes in up to 98 % yield and greater than 99.5 % enantiomeric excess. This ligand coupling reaction is tolerant to multiple substitution patterns and provides access to diverse areas of chemical space in three operationally simple steps from commercially available reagents.

Sigmatropic Rearrangement of Vinyl Aziridines: Expedient Synthesis of Cyclic Sulfoximines from Chiral Sulfinimines.

A novel rearrangement of 2-vinyl aziridine 2-carboxylates to unusual chiral cyclic sulfoximines is described herein. The method allows the synthesis of substituted cyclic sulfoximines in high yields with complete stereocontrol, and tolerates a wide substrate scope. A one-pot process starting directly from sulfinimines provides access to complex chiral sulfoximines in only two steps from commercially available aldehydes.

Development of a flow method for the hydroboration/oxidation of olefins.

A method for the continuous preparation of alcohols by hydroboration/oxidation of olefins using flow techniques is described. The process allows the isolation of up to 120 mmol h(-1) of the desired alcohol in a very rapid manner with good functional group tolerance. The flow setup can be modified to perform a continuous extraction of the desired alcohol from the biphasic mixture produced by the reaction.

Combining two-directional synthesis and tandem reactions. Part 21: Exploitation of a dimeric macrocycle for chain terminus differentiation and synthesis of an sp(3)-rich library.

The application of a tandem condensation/cyclisation/[3+2]-cycloaddition/elimination reaction gives an sp(3)-rich tricyclic pyrazoline scaffold with two ethyl esters in a single step from a simple linear starting material. The successive hydrolysis and cyclisation (with Boc anhydride) of these 3-dimensional architectures, generates unprecedented 16-membered macrocyclic bisanhydrides (characterised by XRD). Selective amidations could then be achieved by ring opening with a primary amine followed by HATU-promoted amide coupling to yield an sp(3)-rich natural product-like library.

Asymmetric synthesis of trisubstituted aziridines via aza-Darzens reaction of chiral sulfinimines.

The aza-Darzens reaction of substituted 2-bromoesters with chiral tert-butane- and mesitylsulfinimines provides a rapid access to a range of highly substituted aziridines in good yields and excellent levels of stereoselectivity. The synthetic potential of this protocol is further enhanced by the successful removal of the sulfinyl motif, yielding simple access to chiral N-H aziridines in just three steps from commercial aldehyde precursors.

Two-directional synthesis and biological evaluation of alkaloid 5-epi-cis-275B'.

The first total synthesis of myrmicine ant alkaloid 5-epi-cis-275B' (4) is presented. A tandem cyclisation established the entire core of the structure in a single transformation as well as the required 2,5-anti stereochemistry. Two-directional synthesis was used to furnish the cyclisation precursor 2, as in each of the subsequent steps towards the natural product.

Isolation of stable non cyclic 1,2-disulfoxides. Revisiting the thermolysis of S-aryl sulfinimines.

The thermolysis of S-aryl sulfinimines is shown to generate 1,2-disulfoxides and disulfides via initial Cope elimination, dimerisation of the produced sulfenic acid to a thiosulfinate, and subsequent disproportionation of the thiosulfinate.

A two-directional approach to pyrrolizidines: total syntheses and biological evaluation of alkaloid cis-223B and (±)-xenovenine.

Total syntheses of alkaloid cis-223B and xenovenine are reported in 3 and 4 steps respectively using a two-directional synthesis/triple reductive amination strategy, and their neurotoxic properties assessed.

Highly diastereoselective radical cyclisations of chiral sulfinimines.

Chiral amines are formed by the highly diastereoselective intramolecular addition of alkyl and aryl radicals onto chiral mesityl sulfinimines.

Cycloaddition of chiral tert-butanesulfinimines with trimethylenemethane.

The cycloaddition of chiral tert-butanesulfinimines with trimethylenemethane is found to give facile access to methylene-pyrrolidines with good yields and diastereoselectivities. The full scope of the cycloaddition is explored, and a range of transformations of the formed methylenepyrrolidines to give a range of functionalized chiral pyrrolidines is presented.