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The Baeyer-Villiger reaction is used extensively in organic chemistry. Sila- and bora-variants have also been documented widely, with these processes underpinning, for example, the Fleming-Tamao oxidation and hydroborative alkene hydration, respectively. By contrast, the development of thia-Baeyer-Villiger reactions involving sulfoxides has long been considered unlikely because competitive oxidation to the sulfone occurs exclusively. Here, we disclose a photoinduced thia-Baeyer-Villiger-type oxidations; specifically, we find that exposure of dibenzothiophene (DBT) derivatives to an iron porphyrin catalyst under Ultraviolet irradiation in the presence of t -BuOOH generates sulfinic esters in up to 87% yield. The produced sulfinic esters are transformed to a variety of biphenyl substrates including biphenyl sulfoxides, sulfones and sulfonamides in 1-2 steps. These results provide a mild process for the selective functionalization of sulfur compounds, and offer a biomimetic approach to convert DBT into 2-hydroxybiphenyl under controllable stepwise pathway. Based upon experimental evidences and DFT calculation, a mechanism is proposed. The development of thia-Baeyer-Villiger reactions has been elusive so far due to competitive oxidation of sulfoxides to sulfones. Here, the authors show a thia-Baeyer-Villiger-type oxidations converting dibenzothiophene derivatives into sulfinic esters with t -BuOOH and an iron catalyst under UV irradiation.

Ethylene glycol condensed with carbonyl compounds in the presence of silica gel or alumina, without solvent and under pressure, affords 1,3-dioxolanes. 2-Amino-2-methylpropanol also condensed with carbonyl compounds in the presence of silica gel or an acid-activated clay, without solvent and under pressure, produces oxazolidines. To explain these results, we propose that the glycol and the aminopropanol react with Brønsted (H + ) and Lewis acid sites (Si and Al) located on the surface of the catalysts, leading to the products via various ionic intermediates. Graphical abstract

Plants modify their volatile chemical signature under pest infestation, which might directly or indirectly improve their defence against threats. These chemical signals have potential in integrated pest management strategies. Macrolophus pygmaeus (Rambur) [Heteroptera: Miridae] is a generalist predatory insect widely used to control the tomato leaf miner, Tuta absoluta (Meyrick) [Lepidoptera: Gelechiidae]. Based on a previous study demonstrating the ability of this mirid species to discriminate non-infested versus T. absoluta -infested tomato plants, our objective was to identify plant volatile chemicals (herbivore-induced plant volatiles—HIPVs) guiding the behaviour of such a generalist predator towards its prey. First, we used coupled gas chromatography-mass spectrometry-electroantennographic detection analysis to screen for active antenna components from the volatile blend released by T. absoluta -infested tomato plants. Dose responses associated with each isolated HIPV were also performed using an electroantennograph. Subsequently, behavioural assays were conducted in a double-choice olfactometer to analyse and identify the behaviourally active chemicals eliciting olfactory responses. Twenty-one total compounds induced antennal responses and six of the 21 evoked positive attractions in M. pygmaeus : ( E )hex-2-enal, 2-carene, α-pinene, β-phellandrene, hexanal, and linalool. A synthetic blend of active HIPVs induced olfactory responses as well as attraction in the bioassays. Our results provided evidence the generalist mirid predator M. pygmaeus uses chemical cues from infested tomato plants to identify plants infested by prey. We discussed how these results can be used to improve existing biological approaches to control the tomato leaf miner , T. absoluta.

The hydrosilylation reaction enables the production of silicon polymers. Platinum-carbene complexes are reported that catalyze the hydrosilylation reaction of alkenes with remarkable efficiency and exquisite selectivity and avoid the formation of platinum colloids. By-products, typically encountered with previous catalytic systems, are suppressed with these platinum derivatives.

The total synthesis of complex natural products remains the most difficult, daunting and challenging endeavor in organic chemistry, as well as one of the most exciting. Marko discusses the development of the modern natural product synthesis.

An efficient, copper-based catalyst has been discovered that oxidizes a wide range of alcohols into aldehydes and ketones under mild conditions. This catalytic system utilizes oxygen or air as the ultimate, stoichiometric oxidant, producing water as the only by-product.

A novel modification of the classical Julia-Lythgoe olefination, using sulfoxides instead of sulfones, affords, after in situ benzoylation and SmI 2 /HMPA or SmI 2 /DMPU-mediated reductive elimination, 1,2-di-, tri- and tetrasubstituted olefins in moderate to good yields and E / Z selectivity. The conditions are mild and the procedure is widely applicable. The reaction mechanism was studied and a general model, describing the reaction selectivity, is proposed.

The hydrosilylation of alkenes and alkynes, that is, the addition of silanes across carboncarbon double or triple bonds, represents the ideal pathway to produce organosilicon compounds. This chapter describes how the use of N‐heterocyclic carbenes (NHCs) has enabled the discovery of unique platinum(0) catalysts for the hydrosilylation of unsaturated carboncarbon bonds. NHC platinum(0) complexes have also been used as hydroboration and diboration catalysts as well as precursors of platinum(II) carbene complexes. Karstedt's catalyst is known to follow the general mechanism described by Chalk and Harrod. Exciting results were obtained with the N‐heterocyclic carbene platinum(0) complexes in alkene hydrosilylation. The use of the hydrosilylation products as advantageous building blocks for organic synthesis is being actively pursued.

The hydrosilylation reaction enables the production of silicon polymers. Platinum-carbene complexes are reported that catalyze the hydrosilylation reaction of alkenes with remarkable efficiency and exquisite selectivity and avoid the formation of platinum colloids. By-products, typically encountered with previous catalytic systems, are suppressed with these platinum derivatives.

Although resveratrol has widely been studied for its potential health benefits, little is known about its metabolic effects in humans. Our aims were to determine whether the polyphenol resveratrol improves insulin sensitivity in type 2 diabetic patients and to gain some insight into the mechanism of its action. After an initial general examination (including blood chemistry), nineteen patients enrolled in the 4-week-long double-blind study were randomly assigned into two groups: a resveratrol group receiving oral 2 × 5 mg resveratrol and a control group receiving placebo. Before and after the second and fourth weeks of the trial, insulin resistance/sensitivity, creatinine-normalised ortho-tyrosine level in urine samples (as a measure of oxidative stress), incretin levels and phosphorylated protein kinase B (pAkt):protein kinase B (Akt) ratio in platelets were assessed and statistically analysed. After the fourth week, resveratrol significantly decreased insulin resistance (homeostasis model of assessment for insulin resistance) and urinary ortho-tyrosine excretion, while it increased the pAkt:Akt ratio in platelets. On the other hand, it had no effect on parameters that relate to β-cell function (i.e. homeostasis model of assessment of β-cell function). The present study shows for the first time that resveratrol improves insulin sensitivity in humans, which might be due to a resveratrol-induced decrease in oxidative stress that leads to a more efficient insulin signalling via the Akt pathway.