Oxidative cleavage of alkenes leading to valuable carbonyl derivatives is a fundamental transformation in synthetic chemistry. In particular, ozonolysis is the mainstream method for the oxidative cleavage of alkenes that has been widely implemented in the synthesis of natural products and pharmaceutically relevant compounds. However, due to the toxicity and explosive nature of ozone, alternative approaches employing transition metals and enzymes in the presence of oxygen and/or strong oxidants have been developed. These protocols are often conducted under harsh reaction conditions that limit the substrate scope. Photochemical approaches can provide milder and more practical alternatives for this synthetically useful transformation. In this review, we outline recent visible-light-promoted oxidative cleavage reactions that involve photocatalytic activation of oxygen via electron transfer and energy transfer. Also, an emerging field featuring visible-light-promoted oxidative cleavage under anaerobic conditions is discussed. The methods highlighted in this review represent a transformative step toward more sustainable and efficient strategies for the oxidative cleavage of alkenes.

Difunctionalizations of alkenes represent one of the most straightforward protocols to build molecular complexity due to the simultaneous construction of two vicinal bonds cross π-bond of alkenes. It is extremely attractive yet challenging to control the stereochemistry outcome of this event. Over the past years, visible-light and Ni-catalyzed asymmetric difunctionalizations of alkenes provide an environmental benign and promising solution for the construction of saturated carbon centers with the control of regio- and enantioselectivity. In this Concept, the initiative and progress of regio- and enantioselective difunctionalizations of alkenes enabled by visible-light and nickel catalysis has been summarized. Moreover, further efforts and directions for the development of visible-light mediated Ni-catalyzed asymmetric difunctionalizations of alkenes has been discussed.

The DIBAL-H reduction of the Baylis-Hillman sugar adduct, obtained from 3-O-benzyl-1,2-isopropylidene-α-D-xylo-pentodialdo-1,4-furanose yielded trisubstituted alkenes by eliminating the β-hydroxyl group. Subsequently, the hydrolysis of the isopropylidene acetal to the corresponding hemiacetal was reacted with N-benzyl hydroxylamine hydrochloride to generate the nitrone, which underwent diastereoselective intramolecular 1,3-dipolar nitrone olefin cycloaddition (INOC) to give an isoxazolidine skeleton. The concomitant reductive cleavage of the N-O bond and benzyl group of the fused isoxazolidines afforded new functionalized aminocyclopentitols in good yields.

Chemical residues in food pose health risks such as cancer and liver issues. This has driven the search for safer natural alternatives to synthetic fungicides and preservatives. The aim of this study was to characterize the chemical composition of the essential oils (EO), determine the polyphenolic contents, and evaluate the in vitro antioxidant and antifungal activities of methanol extracts (ME), essential oils (EO), and powders from Rosmarinus officinalis L. (rosemary) and Thymus ciliatus (Desf) Benth. (thyme) from the M\'sila region, Algeria. The chemical composition of the EOs was determined by GC-MS. R. officinalis EO was composed of 31 components, mainly camphor (41.22%), camphene (18.14%), and α-pinene (17.49%); T. ciliatus EO was composed of 58 components, mainly, in percentage, α-pinene (22.18), myrcene (13.13), β-pinene (7.73), β-caryophyllene (10.21), and germacrene D (9.90). The total phenols and flavonoids were determined spectrophotometrically, and the rosemary ME was found to possess the highest polyphenolic content (127.1 ± 2.40 µg GAE/mg), while the thyme ME had the highest flavonoid content (48.01 ± 0.99 µg QE/mg). The antioxidant activity was assessed using three methods: rosemary ME was the most potent, followed by DPPH (IC50 = 13.43 ± 0.14 µg/mL), β-carotene/linoleic acid (IC50 = 39.01 ± 2.16 μg/mL), and reducing power (EC50 = 15.03 ± 1.43 µg/mL). Antifungal activity was assessed for 32 pathogenic and foodborne fungi. Four methods were applied to the solid medium. Incorporating the powdered plant into the culture medium (at 10%) reduced the fungal growth to greater than 50% in 21.88% and 6.25% of all fungal isolates, for R. officinalis and T. ciliatus, respectively. The ME, applied by the well diffusion method (0.1 g/mL), was less effective. Different concentrations of EO were tested. Incorporating the EO into the culture medium (1500 μL/L) inhibited 50% of the molds to levels of 50 and 75% for R. officinalis and T. ciliatus, respectively, with the complete inhibition of four fungi. Fumigated EO (15 μL) inhibited 65% of the molds to levels of 65 and 81.25% for R. officinalis and T. ciliatus, respectively, with the complete inhibition of five fungi. There was little to no sporulation in conjunction with the inhibition. Our results revealed some of the potential of the studied plants to fight foodborne molds and presented their promising characteristics as a source of alternatives to chemical pesticides and synthetic preservatives. Further studies are needed to find adequate application techniques in the food safety area.

Dehydration is an effective method for the long-term storage and aroma retention of gonggan (Citrus sinensis Osb. \'Deqing Gonggan\'), which is a Chinese variety of citrus, with unique and characteristic floral, fruity, and citrus flavors. However, the aroma profiles of gonggans prepared using oven- and freeze-drying, the most widely-used drying methods, remain unclear. In this study, a total of 911 volatile organic compounds (VOCs) were detected in dried gonggan. These were primarily composed of alcohols (7.69%), aldehydes (7.03%), esters (15.38%), ketones (7.58%), and terpenoids (23.19%). A total of 67 odorants contributed significantly to the overall aroma of dried gonggans, with the major odor qualities being detected as green, citrus, fruity, floral, and sweet. These were mainly attributed to the presence of aldehydes, esters, and terpenoids. Freeze-drying was more effective in maintaining the unique citrus and mandarin-like aromas attributed to compounds such as limonene, citrial, β-myrcene, β-pinene, and γ-terpinene. Moreover, (E,E)-2,4-decadienal had the highest relative odor activity value (rOAV) in freeze-dried gonggans, followed by (E)-2-nonenal, furaneol, (E, E)-2, 4-nonadienal, and E-2-undecenal. Oven-drying promoted the accumulation of terpenes such as octatriene, trans-β-ocimene, cyclohexanone, copaene, and ɑ-irone, imparting a soft aroma of flowers, fruits, and sweet. Increasing the temperature led to an increase in existing VOCs or the generation of new VOCs through phenylpropanoid, terpenoid, and fatty acid metabolism. The findings of this study offer insights into an optimized procedure for producing high-quality dried gonggans. These insights can be valuable for the fruit-drying industry, particularly for enhancing the quality of dried fruits.

Enzymes capable of assimilating fluorinated feedstocks are scarce. This situation poses a challenge for the biosynthesis of fluorinated compounds used in pharmaceuticals, agrochemicals, and materials. We developed a photoenzymatic hydrofluoroalkylation that integrates fluorinated motifs into olefins. The photoinduced promiscuity of flavin-dependent ene-reductases enables the generation of carbon-centered radicals from iodinated fluoroalkanes, which are directed by the photoenzyme to engage enantioselectively with olefins. This approach facilitates stereocontrol through interaction between a singular fluorinated unit and the enzyme, securing high enantioselectivity at β, γ, or δ positions of fluorinated groups through enzymatic hydrogen atom transfer-a process that is notably challenging with conventional chemocatalysis. This work advances enzymatic strategies for integrating fluorinated chemical feedstocks and opens avenues for asymmetric synthesis of fluorinated compounds.

Novel chalcogen-containing amides and esters bearing the benzenesulfonamide moiety have been synthesised upon nucleophilic conjugate addition of thiols and selenols to suitable electron-deficient alkenes. The activity of the synthesised compounds as Carbonic Anhydrases inhibitors has been investigated in vitro and the inhibition mechanism has been elucidated by X-rays studies.

Although highly appealing for rapid access of molecular complexity, multi-functionalization of alkenes that allows incorporation of more than two functional groups remains a prominent challenge. Herein, we report a novel strategy that merges dipolar cycloaddition with photoredox promoted radical ring-opening remote C(sp3)-H functionalization, thus enabling a smooth 1,2,5-trifunctionalization of unactivated alkenes. A highly regioselective [3+2] cycloaddition anchors a reaction trigger onto alkene substrates. The subsequent halogen atom transfer (XAT) selectively initiates ring-opening process, which is followed by a series of 1,5-hydrogen atom transfer (1,5-HAT) and intermolecular fluorine atom transfer (FAT) events. With this method, site-selective introduction of three different functional groups is accomplished and a broad spectrum of valuable β-hydroxyl-ε-fluoro-nitrile products are synthesized from readily available terminal alkenes.

A novel protocol to access vinyl sulfones and internal/terminal olefins via cobalt-catalyzed acceptorless dehydrogenation coupling (ADC) has been established. This system enables the divergent synthesis of three kinds of olefin compounds through the coupling of alcohols and sulfones under oxidant-free conditions. The broad applicability of this procedure is demonstrated by over forty olefin products, including pharmaceutical-related compounds and complex substrates, in a one-pot process. Preliminary mechanistic studies were conducted, and a proposed reaction pathway was presented.

We present a method for site-selective diversification of peptides via Pd-catalyzed β-C(sp3)-H olefination/cyclization. In this protocol, the native methionine residue acts as a directing group, enabling site-specific olefination/cyclization of peptides. This chemistry demonstrates broad substrate scope, offering a versatile tool for peptide ligation.