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Synthesis of the C19-truncated maltepolide E has been accomplished via a diene–ene RCM strategy without damage to the C11–C14 alkenyl epoxy unit. Upon release of the C17-OH group, it attacked at the C14 position with double bond migration and epoxide ring-opening to furnish the C19-truncated maltepolide A and B as proposed for the biosynthesis of maltepolides. Preliminary cytotoxicity data of the synthesized C19-truncated maltepolides against L929 mouse fibroblast cell line suggest irrelevance of the vinyl epoxide and importance of the conjugated dienyl keto unit for the observed anticancer activity.

The uranyl with two U=O double bonds is a well-known and predominant form of uranium in the environment, but the carbon-based analog with two U=C double bonds has rarely been synthesized. Here, we ...

The detailed investigation of heavy oil catalytic upgrading is important because heteroatom-containing compounds are detrimental to refining processes and the environment. Atmospheric residues (ARs) with different compositions were hydrotreated in two plug-flow reactors in series to study the reactivity of various species over the commercial catalysts at the molecular level. A 15-T Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer equipped with atmospheric pressure photoionization (APPI) was applied to determine the molecular composition without chemical derivatization. Here, we examined the changes in bulk and molecular composition of two different ARs. The catalytic reactivity of the ARs was determined with respect to the relative abundance of the double bond equivalent (DBE) distribution dependent on carbon number for each class, such as hydrocarbon, sulfur, and nitrogen species. Reactivities and reaction routes of hydrocarbon, sulfur, and nitrogen species were discussed in detail at the molecular level.

Biodiesel is composed of various types of methyl ester compounds with different concentrations. The role of unsaturation degree was observed through single-molecule droplet combustion from three fatty acid methyl ester compounds. This research was conducted under normal gravity at ambient temperature and atmospheric pressure. Analysis of droplet combustion characteristics was observed along the heating, evaporation, ignition, and combustion stages. The cis configuration and allyl groups in unsaturated molecules related to different unsaturation degrees affect the droplet combustion process. Allyl and bis-allyl groups play an important role in accelerating hydrogen atom abstraction due to the weaker bond dissociation energy of the C H bond adjacent to the carbon double bond. The lower energy gap in unsaturated molecules is prone to electron excitation. Increasing the unsaturation degree resulted in shorter ignition delay and burning duration but higher droplet temperature, burning rate constant, specific power output, and flame dimensions. Soot particles formed above the flame tip on the unsaturated molecules gave a higher flame dimension. A high concentration of linoleic methyl ester in biodiesel fuel is recommended due to of high power output. However, the soot formation at a higher level of unsaturation degree should be considered.

trans-Anethole (anethole) is a phenylpropanoid; with other drugs, it exhibits synergistic activity against several fungi and is expected to be used in new therapies that cause fewer patient side effects. However, the detailed substructure(s) of the molecule responsible for this synergy has not been fully elucidated. We investigated the structure-activity relationships of phenylpropanoids and related derivatives, with particular attention on the methoxy group and the double bond of the propenyl group in anethole, as well as the length of the p-alkyl chain in p-alkylanisoles. Antifungal potency was largely related to p-alkyl chain length and the methoxy group of anethole, but not to the double bond of its propenyl group. Production of reactive oxygen species also played a role in these fungicidal activities. Inhibition of drug efflux was associated with the length of the p-alkyl chain and the double bond of the propenyl group in anethole, but not with the methoxy group. Although a desirable synergy was observed between n-dodecanol and anethole or p-alkylanisoles with a length of C2-C6 in alkyl chains, it cannot be explained away as being solely due to the inhibition of drug efflux. Similar results were obtained when phenylpropanoid derivatives were combined with fluconazole against Candida albicans.

Although surfactants have been widely used in skin care and other related applications, our knowledge about how surfactants interact with stratum corneum (SC) lipids remains limited. This work reports how surfactants interact with a lipid SC model by neutron diffraction and molecular dynamics (MD) simulations, focusing on examining the impact of surfactant molecular architecture. The surfactant-SC mixed membrane was constructed by an equimolar mixture of ceramide/cholesterol/fatty acids and surfactant at 1% molar ratio of total lipids. The arrangements of water and surfactant molecules in the membrane were obtained through neutron scattering length density (NSLD) profiles via contrast variation method, meanwhile, MD simulation clearly demonstrated the mechanism of hydration change in the surfactant-model SC mixed membrane. No drastic difference was detected in the repeating distance of the short periodicity phase (SPP) upon adding surfactants, however, it significantly enhanced the membrane hydration and reduced the amount of phase separated crystalline cholesterol, showing a strong dependence on surfactant chain length, branching and double bond. This work clearly demonstrates how surfactant architecture affects its interaction with the SC membrane, providing useful guidance for either choosing an existing surfactant or designing a new one for surfactant-based transdermal application.

Hydric alcohols are important synthetic intermediates used to manufacture polymer, fine chemicals, and commodity products. Recent environmental problems due to fossil fuel-based non-degradable products have call for the advancement in research towards developing an alternate source that can sustainably substitute petroleum. In this direction, we have conceptualized a combined fermentation and catalytic process to obtain biorenewable branched diols from biomass. The significant yield of the desired diol products was obtained from different lignocellulose-based cyclic esters under optimized conditions. In order to know the universality of our process, saturated, partially saturated and unsaturated lactones were tested, which gave up to 99% conversion and (∼68-91%) diol’s yield. Finally, a plausible mechanism is proposed which is more likely to follow a pathway involving ring-opening reaction via partial hydrogenation of the double bond of the 6-amyl-α-pyrone. Keyords Biomass conversion, diols, 2-pyrone, hydrogenation, polymer precursor

Improving the selectivity of photocatalysis and reducing the generation of toxic by-products are the two key challenges for the development of highly efficient and stable photocatalysts. In this work, it was revealed that Zn-Ti-layered double hydroxide (ZT-LDH) photocatalyst, which generated less intermediates, showed better toluene degradation efficiency (removal ratio, 75.2%) and stability, compared with P25 (removal ratio, 10.9%). During the photocatalytic toluene degradation, benzaldehyde and benzoic acid were the main intermediates existed in the gas phase and on the surface of the catalyst, respectively. By combining experiments with theoretical calculation, it was found that the hydrogen atoms on the hydroxyl groups in the LDH would selectively attract the oxygen atoms in the carbon–oxygen double bond of the two major intermediates, facilitating their adsorption and activation on ZT-LDH. Besides, the surface electronic structure of ZT-LDH was demonstrated to facilitate the ring-opening reaction of the two major intermediates, eventually maintaining high activity and stability. This work could provide new molecular perspectives for understanding the photocatalytic reactions in VOCs degradation and developing efficient and stable photocatalysts.

Already 1 mol-% of subvalent [Ga(PhF)2]+[pf]– ([pf]– = [Al(ORF)4]– , RF = C(CF3)3) initiates the hydrosilylation of olefinic double bonds under mild conditions. Reactions with HSiMe3 and HSiEt3 as substrates efficiently yield anti-Markovnikov and anti-addition products, while bulkier substrates like HSiiPr3 are less reactive. Investigating the underlying mechanism by gas chromatography and STEM analysis, we unexpectedly found that H2 and metallic Ga0 formed. Without addition of the olefin, the formation of R3Si–F–Al(ORF)3 (R = alkyl) was observed, a typical degradation product of the [pf]– anion in the presence of a small silylium ion. Electrochemical analysis revealed a surprisingly high oxidation potential of univalent [Ga(PhF)2]+[pf]– in the weakly coordinating, but polar ortho-difluorobenzene of E1/2(Ga+/Ga0; oDFB) = +0.26–0.37 V vs. Fc+ /Fc (depending on the scan rate). Apparently, the subvalent Ga+, mainly known as reductant, initially oxidizes the silane, and generates a highly electrophilic, silane-supported, silylium ion representing the actual catalyst. Consequently, the [Ga(PhF)2]+[pf]– /HSiEt3 system also hydrodefluorinates C(sp3)–F bonds in 1-fluoroadamantane, 1-fluorobutane and PhCF3 at room temperature. In addition, both catalytic reactions may also be initiated by using only 0.2 mol-% of [Ph3C]+[pf]– as silylium ion generating initiator. These results indicate that silylium ion-catalysis is possible with the straight forward accessible weakly coordinating [pf]– anion. Apparently, the kinetics of hydrosilylation and hydrodefluorination are faster than that of anion degradation under ambient conditions. These findings open new windows for main group catalysis.

Bioactive isolation was performed on the stem bark of Datuan (Ficus vasculosa Wall. Ex Miq), and extraction was carried out via the maceration method using acetone as a solvent. Furthermore, an attractant bioactivity test was conducted on acetone extract, A-G fraction, and composition of the isolates. The separation and purification via column chromatography produced a D8.3.5.7 fraction in the form of needle crystal of about 50 mg, at a melting point of 136°C–138.7°C. Thin-layer chromatography (TLC) analysis showed a single spot at an Rf value of 0.57 (n-hexane eluent: ethyl acetate 7:3), 0.36 (DCM eluent), and 0.24 (CHCl3 eluent). The isolated compounds were identified using infrared and UV–Vis spectrophotometry, as well as mass spectrometry. The characterization of the infrared spectrum of the isolated compound showed a strong OH goo band at 3461 cm-1 region and the absorption band at 2936.25 cm−1 exhibited a stretch of CH alkanes. These two bands are supported by the vibration at 1378.47 and 1462.55 cm−1 for CH absorption of methyl and methylene. The absorption band in the 1622 cm−1 region showed a stretch of conjugated C=C double bond, which is supported by absorption at 918.96 and 966.22 cm−1 as C–H alkene. The UV–Vis spectrophotometry showed absorption at λmax 263.97 nm A = 0.483, which was the result of electronic transition π → π*, and at λ 331.0 nm A = 0.274, which was an electronic result of n → π*. Meanwhile, identification via mass spectrometry that produces isolate has a molecular weight of 414.1 m/e with the formula C29H50O. Therefore, the bioactivity test results on compound D8.3.5.7 had an attractant activity of 71.67% against warehouse pests (Sitophilus oryzae L.) and an interest index of 0.63. Keywords: attractant. bioactive, F. vasculosa Wall.ex Miq., S. oryzae

Quorum sensing (QS) plays an essential role in virulence factor production, biofilm formation, and antimicrobial resistance. As a potent QS inhibitor, hordenine can inhibit both QS and biofilm formation in Pseudomonas aeruginosa and Serratia marcescens. In this work, we tested the QS inhibitory potential of 27 hordenine analogs against QS and biofilm formation in P. aeruginosa and S. marcescens. Among the tested analogs, seven (12, 28, 27, 26, 2, 23, and 7) exhibited strong QS inhibitory activity against P. aeruginosa, five of which (12, 28, 27, 26, and 2) showed better inhibitory activity than hordenine. In addition, seven analogs (28, 12, 23, 7, 26, 2, and 27) exhibited better biofilm inhibition against P. aeruginosa than hordenine. Four analogs (7, 28, 2, and 12) showed QS inhibitory activity against S. marcescens, two of which (7 and 28) demonstrated better inhibitory activity than hordenine. Furthermore, analog 7 showed similar biofilm inhibition against S. marcescens as hordenine. Structure-activity relationship (SAR) analysis indicated that the inhibitory activities of the analogs were related to four factors, i.e., carbon chain length, presence or absence of an α,β-C Created by potrace 1.16, written by Peter Selinger 2001-2019 C bond, amino group with/without lipophilic group, such as methyl group, and hydroxyl group in benzene ring.

Bridged indigos were synthesized by bridging the two nitrogen atoms in the indigo structure with a carbon chain, and their properties were carefully examined. These bridged indigos have intrinsic planar chirality, and the enantiomers were separated using chiral high-performance liquid chromatography. When the chiral bridged indigos were subjected to thermo- and photoisomerization, the corresponding (Z)-indigo was not observed at all, and racemization was observed. This phenomenon is caused by the low activation energy of inversion due to the 1.5 bond order of the double bond of the indigo skeleton and the large energy difference between the ground states of (E)-indigo and (Z)-indigo.

16,17-Dihydroheronamide C (8) and ent-heronamide C (ent-1) were designed as probes for the mode-of-action analysis of heronamide C (1). These molecules were synthesized by utilizing a highly modular strategy developed in the preceding paper. The evaluation of the antifungal activity of these compounds revealed the exceptional importance of the C16-C17 double bond for the antifungal activity of heronamide C and the existence of chiral recognition between heronamide C (1) and cell membrane components.

Characterizing the molecular composition of cloud water could provide unique insights into aqueous chemistry. Field measurements were conducted at Mt. Tianjing in southern China in May, 2018. There are thousands of formulas (C5–30H4–55O1–15N0–2S0–2) identified in cloud water by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). CHON formulas (formulas containing C, H, O, and N elements; the same is true for CHO and CHOS) represent the dominant component (43.6 %–65.3 % of relative abundance), followed by CHO (13.8 %–52.1%). S-containing formulas constitute ∼5 %–20 % of all assigned formulas. Cloud water has a relative-abundance-weighted average O/C of 0.45–0.56, and the double bond equivalent of 5.10–5.70. Most of the formulas (>85 %) are assigned as aliphatic and olefinic species. No statistical difference in the oxidation state is observed between cloud water and interstitial PM2.5. CHON with aromatic structures are abundant in cloud water, suggesting their enhanced in-cloud formation. Other organics in cloud water are mainly from biomass burning and oxidation of biogenic volatile organic compounds. The cloud water contains more abundant CHON and CHOS at night, which are primarily contributed by −N2O5 function and organosulfates, demonstrating the enhanced formation in dark aqueous or multi-phase reactions. While more abundant CHO is observed during the daytime, likely due to the photochemical oxidation and photolysis of N- or S-containing formulas. The results provide an improved understanding of the in-cloud aqueous-phase reactions.

In this paper, a novel polarization method was proposed, in which a partially isolated C=C double bond was constructed in the PVDF molecular chain by designing a step-by-step polarization process. The dielectric and piezoelectric properties of PVDF films were studied. The results show that the piezoelectric coefficient d33 is significantly improved. Specifically, the d33 increases from − 6.5 pC/N for traditional polarization to − 13.5 pC/N by 107%. The microstructures were investigated by Fourier transform infrared spectroscopy and X-ray Photoelectron Spectroscopy, and it is confirmed that the dehydrogenation defluorination reaction was effectively induced by the polarization method, and the C=C double bond is constructed. It is also observed that the introduction of C=C bond increases the content of polar β phase, and consequently its piezoelectric properties of PVDF films. This method improves the piezoelectric performance while maintaining the original excellent performance, and further broadens the application scenarios of PVDF.

Novel 6-arylethyl-1,2,4-trioxanes6a-i and 7a-i are easily accessible in one step from the diimide reduction of 6-arylvinyl-1,2,4-trioxanes 5a-i. All of these new trioxanes were assessed for their oral antimalarial activity against multidrug-resistant Plasmodium yoelii nigeriensis in a Swiss mice model. Most of the saturated trioxanes 6c, 6f, 6g, 6h, and 6i, the active compounds of the series, provided 100% protection to the malaria-infected mice at a dose of 24 mg/kg × 4 days. Further, trioxane 6i, the most active compound of the series, also showed 100% protection even at a dose of 12 mg/kg × 4 days and 20% protection at a dose of 6 mg/kg × 4 days. In this model, β-arteether provided 100% protection at a dose of 48 mg/kg × 4 days and only 20% protection at a dose of 24 mg/kg × 4 days via the oral route, which was found to exhibit 4-fold antimalarial activity compared with the currently used drug β-arteether.

To realize a sustainable, carbon-free society, catalysts for the synthesis of ammonia using renewable energy under mild reaction conditions (

Amidation is an important reaction for bioderived platform molecules, which can be upgraded for use in applications such as polymers. However, fundamental understanding of the reaction especially in the presence of multiple groups is still lacking. In this study, the amidation of dimethyl fumarate, maleate, and succinate through ester ammonolysis was examined. The reaction networks and significant side reactions, such as conjugate addition and ring closing, were determined. A preliminary kinetic comparison among additional C4 and C6 esters showed a significant correlation between molecular structure and ammonolysis reactivity. Esters with a C=C double bond in the molecule backbone were found to have higher ammonolysis reactivity. To improve the selectivity to unsaturated amides rather than byproducts, the effects of thermal conditions and additives in dimethyl fumarate ammonolysis were examined. Lower temperature and decreasing methoxide ion concentration in the solution relative to the base case conditions increased the fumaramide selectivity from 67.1 to 90.6%.

Inspired by the biogenetic proposal of an intramolecular Diels–Alder (IMDA) cycloaddition, the total synthesis of natural product nahuoic acid A, a cofactor-competitive inhibitor of the epigenetic enzyme lysine methyl transferase SETD8, has been carried out. A non-conjugated pentaenal precursor was synthesized with high levels of stereoselectivity at seven stereogenic centers and with the appropriate control of double bond geometries. Although the IMDA reaction of the non-conjugated pentaenal using Me2AlCl for catalysis at −40 °C selectively afforded the trans-fused diastereomer corresponding to the Re-endo mode of cycloaddition, under thermal reaction conditions it gave rise to a mixture of diastereomers, that preferentially formed through the exo mode, including the cis-fused angularly-methylated octahydronaphthalene diastereomer precursor of nahuoic acid A. The natural product could be obtained upon oxidation and overall deprotection of the hydroxyl groups present in the Si-exo IMDA diastereomer., The total synthesis of natural product nahuoic acid A, a cofactor-competitive inhibitor of the epigenetic enzyme lysine methyl transferase SETD8, has been carried out based on the biogenetic proposal of an intramolecular Diels–Alder (IMDA) cycloaddition.

Hydroalkylation, the direct addition of a C(sp3)–H bond across an olefin, is a desirable strategy to produce valuable, complex structural motifs in functional materials, pharmaceuticals, and natural products. Herein, we report a reliable method for accessing α-branched amines via nickel-catalyzed hydroalkylation reactions. Specifically, by using bis(cyclooctadiene)nickel (Ni(cod)2) together with a phosphine ligand, we achieved a formal C(sp3)–H bond insertion reaction between olefins and N-sulfonyl amines without the need for an external hydride source. The amine not only provides the alkyl motif but also delivers hydride to the olefin by means of a nickel-engaged β–hydride elimination/reductive elimination process. This method provides a platform for constructing chiral α-branched amines by using a P-chiral ligand, demonstrating its potential utility in organic synthesis. Notably, a sulfonamidyl boronate complex formed in situ under basic conditions promotes ring-opening of the azanickellacycle reaction intermediate, leading to a significant improvement of the catalytic efficiency., Catalytic addition of a carbon chain and a hydrogen across a double bond has often required an added hydride source. Here the authors show a method to add alkanes with an amino functionality to olefins, wherein a nickel catalyst uses the amine itself as the hydride source, obviating an external hydride reagent.

Epoxy/Al 2 O 3 composites are widely used as electrical insulating materials for high voltage electrical apparatuses. Organic acid anhydrides are important curing agents of electrical insulating epoxy composites. Functional groups and molecular structures of the acid anhydrides play significant roles in determining physical properties of the epoxy/Al 2 O 3 composites. In this work, we investigate effects of the methyl and carbon-carbon double bond in organic acid anhydride molecule on the dielectric properties of epoxy/Al 2 O 3 composite. We test the resistivities and AC breakdown voltages of epoxy/Al 2 O 3 composites cured with five kinds of anhydrides, which are only different in the number and position of methyl and double bond. To explore the influence laws obtained from experimental results, we analyze the distributed energy level structures of five epoxy resin/anhydride oligomer molecules by carrying out a quantum chemical calculation, and the laws are used to predict the relative magnitude of molecular orbital energy levels of epoxy resin/phthalic anhydride oligomer molecule, which are consistent with the energy levels calculated. The double bond in acid anhydride molecule affects the LUMO and HOMO energy levels of an epoxy resin/anhydride polymer molecule, and the methyl in acid anhydride molecule affects the strengths of hydrogen bonds formed between the molecular chains and the silane coupling agents.

The tung tree (Vernicia fordii) is a non-edible oil plant native to southern China and was introduced in Japan in the nineteenth century. The tree produces tung oil, which is composed of approximately 80% α-eleostearic acid (9c, 11t, 13t-octadecatrienoic acid), 7% linoleic acid, and 6% oleic acid. Tung oil may be a non-edible source of biodiesel fuel (BDF) production. The iodine value (IV) is one of parameters to guarantee BDF quality, and the most common method for the determination of IV is the Wijs method. The IV can be calculated from the average molecular weight and the number of double bonds from the GC–MS data. In this study, the IVs of olive, castor, soybean, linseed, and perilla BDF using the Wijs method were found to be almost the same as the calculated IV. On the other hand, the IV of tung BDF by the Wijs method indicated a significantly lower value than that of the calculated value. To determine the cause of this discrepancy, the samples before and after halogenation using the Wijs method, were analyzed by 1H NMR. The conjugated double bond signals did not disappear, and a broad double bond signal remained in the tung BDF spectrum after halogenation. These results demonstrated that iodine, with a large atomic radius, could not react completely with the three conjugated double bonds in α-eleostearic acid. Therefore, the IV of tung BDF was significantly lower than the calculated value.

Lithium–sulfur batteries possess excellent potential because of its about fivefold energy density promotion compared with traditional lithium-ion batteries. Nevertheless, further application has been hindered by rapid capacity attenuation largely result from the shuttle effect caused by intermediate polysulfides diffusion. Appropriate binders can play a crucial part of anchoring the lithium polysulfides in sulfur cathode through robust chemical bonds hence enhance the electrochemical performance of lithium–sulfur batteries. Herein, we explored a new type of binder (chloroprene rubber) that double bond is designed in the binder structure as the vulcanizable group which could significantly enhance the cycle performance of Li–S batteries. The evolution of the chemical bond and the effects of chemical structure of polymer binders were studied in detail. The resulting electrodes exhibit a high initial capacity of 5.43 mAh cm−2 and a reversible capacity retention of 4.06 mAh cm−2 after 120 cycles at 0.05 C, which is superior to Li–S battery with polyvinylidene fluoride (PVDF) binder. The improved performance is due to the vulcanizable double bonds, which has been demonstrated to efficaciously in situ anchoring the polysulfides to the S-cathodes by the breakage of C=C to form C–S bonds.

Mechanistic study on the 1,3,2-diazaphospholene (1)-catalyzed reduction reaction of allyl 2-phenylacrylate 4 with HBpin or ammonia borane (AB) was systematically performed by the density functional theory (DFT) method. When HBpin is employed as the reductant, the reductive Ireland-Claisen (IC) rearrangement reaction occurs. First, the active species P-hydrido-1,3,2-diazaphospholene 3 is generated through the metathesis reaction of 1 with HBpin. Next, the terminal C═C double bond of 4 is inserted into the P-H bond of 3 to produce 6a through the 1,2-addition (Markovnikov) step, which is followed by the pinB-H bond activation to afford key boron enolate 8. Then, 8 undergoes the [3,3] rearrangement that is followed by the alcoholysis reaction with methanol leading to the final product γ,δ-unsaturated carboxylic acid. The [3,3] rearrangement step is the rate-determining step with the Gibbs energy barrier (ΔG≠) and Gibbs reaction energy (ΔG) of 23.9 and -27.5 kcal/mol, respectively. When AB is employed as the reductant, the transfer hydrogenation reaction occurs through two comparable pathways, 1,2- and 1,4-transfer hydrogenation pathways. The former pathway directly leads to the hydrogenation product with the ΔG≠ and ΔG values of 22.4 and -27.7 kcal/mol, respectively. The latter pathway produces an enolate intermediate (rate-determining step, ΔG≠/ΔG = 24.1/-0.3 kcal/mol) first, which then prefers to undergo the enol-keto tautomerism instead of the [3,3] rearrangement to afford the hydrogenation product. Obviously, the generation of the boron enolate plays a crucial role in the reductive IC rearrangement reaction because it prevents the enol-keto tautomerism.

The tandem catalytic functionalization/carboxylation of double as well as triple carbon-carbon bonds with CO2 represent an emerging research area in synthetic organic methodology. In particular, the combination of mild reaction conditions, stoichiometric acceptor/donorless conditions (visible light photoredox catalysis) and chiral catalysts contributed to a rapid development of this intriguing research area capable of creating chemical diversity/ complexity from readily available unsaturated hydrocarbons and CO2 as a C1-buinding block. The most recent developments in the field have been collected in the present review article and organized, based on the different sets of π-systems/intermediates/reactive partners employed (i.e., nickelalactones, organo-halides) as well as synthetic strategies (i.e., visible-light photo redox catalysis).

The aim of the present study is to report the isolation, structural elucidation, and antiviral evaluation of four new withanolide-type steroids, named nicansteroidins A-D (1-4), together with nine related known compounds (5-13) isolated from the aerial parts of Physalis nicandroides. Their structures were established based on an extensive spectroscopic analysis, including 1D and 2D NMR techniques. Outstandingly, nicansteroidins A and B possess an unusual side chain with an exocyclic double bond on the δ-lactone system, whereas nicansteroidins C and D have an uncommon cycloperoxide functionality in ring A as distinct structural motifs. Their biological evaluation as inhibitors of human immunodeficiency virus type 1 replication revealed that two compounds from this series, 7 and 13, displayed strong inhibition of HIV-1 replication with IC50 values lower than 2 μM. Moreover, cellular mechanism experiments showed that the main target of these compounds in the HIV replication cycle is viral transcription. This study is the first report of withanolide-type steroids as HIV inhibitors and provides insight into their potential as candidates for further preclinical studies.

The ligand-regulated regiodivergent hydroarylation of the distal double bond of allenamides with aryl boronic acid was achieved in the presence of palladium(II) catalysts, delivering a variety of functionalized enamide with excellent E selectivity and Markovnikov/anti-Markovnikov selectivity. Two possible coordination intermediates were proposed to be responsible for the regiodivergent hydroarylation: (1) The coordination Intermediate I, which was proposed to be formed through the coordination of MeCN, distal double bond, phenyl to palladium, led to the aryl group away from the Intermediate I, inducing excellent E selectivity and anti-Markovnikov selectivity. (2) A switch of regioselectivity to 1,2-Markovnikov hydroarylation was obtained using bidentate phosphine ligand (dppf or Xantphos). The formed coordination Intermediate II led to the N-tether away from the Intermediate II and at the trans position of aryl, resulting in excellent E selectivity and Markovnikov selectivity. Meanwhile, tentative investigation on the mechanism proved that the hydron source of this hydroarylation is more likely to be boronic acid. The transmetallation between aryl boronic acid and palladium catalyst was the initial step of this transformation.

Three isomers of the allyl cation C3H5+ were obtained in salts with the carborane anion CHB11Cl11-. Two of them, angular CH3-CH=CH+ (I) and linear CH3-C+=CH2 (II), were characterized by X-ray crystallography, and the third one, (CH2CHCH2)+ (III), is formed in an amorphous salt. The stretch vibration of the charged double bond C=C+ of I and II is decreased by 162 cm-1 (I) or 76 cm-1 (II) as compared to that of neutral propene. This result contradicts the prediction of DFT and MP2 calculations with the 6-311G++(d,p) basis set that the appearance of the positive charge on the C=C bond should increase its stretch vibration by 200 cm-1 (I) or 210 cm-1 (II). According to infrared spectra, the CC bonds in isomer III have one-and-a-half bond status. Isomers I and II in the crystal lattice are stabilized due to uniform ionic interactions with neighboring anions with partial transfer of a positive charge to them. Additional stabilization of II is provided by a weak hyperconjugation effect. Isomer III is stabilized in the amorphous phase due to ion paring with a counterion and a strong intramolecular hyperconjugation effect.

Structural characterization of glycerophospholipids beyond the fatty acid level has become a major endeavor in lipidomics, presenting an opportunity to advance the understanding of the intricate relationship between lipid metabolism and disease state. Distinguishing subtle lipid structural features, however, remains a major challenge for high-throughput workflows that implement traditional tandem mass spectrometry (MS/MS) techniques, stunting the molecular depth of quantitative strategies. Here, reversed phase liquid chromatography is coupled to parallel reaction mass spectrometry utilizing the double bond localization capabilities of ultraviolet photodissociation (UVPD) mass spectrometry to produce double bond isomer specific responses that are leveraged for relative quantitation. The strategy provides lipidomic characterization at the double bond level for phosphatidylcholine phospholipids from biological extracts. In addition to quantifying monounsaturated lipids, quantitation of phospholipids incorporating isomeric polyunsaturated fatty acids is also achieved. Using this technique, phosphatidylcholine isomer ratios are compared across human normal and tumor breast tissue to reveal significant structural alterations related to disease state.

The photolytic radical-induced vicinal azidooxygenation of synthetically important and diverse functionalized substrates including unactivated alkenes is reported. The photoredox-catalyst/additive-free protocol enables intermolecular oxyazidation by simultaneously incorporating two new functionalities; C-O and C-N across the C=C double bond in a selective manner. Mechanistic investigations reveal the intermediacy of the azidyl radical facilitated via the photolysis of λ3-azidoiodane species and cascade proceeding to generate an active carbon-centered radical. The late-stage transformations of azido- and oxy-moieties were amply highlighted by assembling high-value drug analogs and bioactive skeletons.

Conjugated azapolyenes (azabuta-1,3-dienes, aza-/diaza-/oxaza-/oxadiazahexa-1,3,5-trienes) are highly reactive in electrocyclization reactions, which makes them convenient precursors for the synthesis of a wide range of four-, five-, and six-membered nitrogen heterocycles that are of relevance for medicinal chemistry. Ring opening reactions of 2H-azirines and azoles containing an N–N or N–O bond, initiated by a transition metal carbene, have become increasingly important in recent years, since they easily allow the generation of azapolyenes with different numbers of double bonds and heteroatoms in various positions. This review summarizes the literature, published mainly in the last decade, on the synthetic and mechanistic aspects of electrocyclizations of azapolyenes generated by the carbene method.

Acetylene derivatives of 1,2,4-oxadiazoles, i.e., 5-(2-arylethynyl)-3-aryl-1,2,4-oxadiazoles, have been obtained, for the first time reported, from 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles by their bromination at the carbon–carbon double bond followed by di-dehydrobromination with NaNH2 in liquid NH3. The reaction of the acetylenyl-1,2,4-oxadiazoles with arenes in neat triflic acid TfOH (CF3SO3H) at room temperature for 1 h resulted in the formation of E/Z-5-(2,2-diarylethenyl)-3-aryl-1,2,4-oxadiazoles as products of regioselective hydroarylation of the acetylene bond. The addition of TfOH to the acetylene bond of these oxadiazoles quantitatively resulted in E/Z-vinyl triflates. The reactions of the cationic intermediates have been studied by DFT calculations and the reaction mechanisms are discussed.

Abstract The paper describes the synthesis of novel strained hydrocarbons based on a diene of the norbornene series, namely 5-methylene-2-norbornene, using catalytic cyclopropanation with diazomethane. The study demonstrated the possibility of selective cyclopropanation solely along the endocyclic double bond. The physicochemical properties of the hydrocarbons were investigated systematically. These hydrocarbons were shown to have an advantageous combination of high density, low freezing point, and high energy density value. The study’s findings indicate that the compounds synthesized are promising as a component of high-energy-density fuels for modern jet engines.

Current problems involving the use of flax product waste for obtaining products utilized for the production of cosmetics with sunscreen and antioxidant properties were examined. Ethanol lignin was obtained from flax shives as well as from raw materials subjected to alkaline pulping or biochemical modification. The bioprocessing included a stage of enzymatic degradation of the noncellulose polysaccharides to give aldoses and a stage of isothermal aging at 95°C. Chemical transformations in the polymer were studied by Fourier-transform infrared spectroscopy (FTIR) with resolution of the spectral curve into elementary vibrational bands of the main atomic groups. The spectra were analyzed using the C–C-stretching vibrational band of the aromatic ring at 1510 cm–1 as the internal standard. The enhanced absorption of the hydroxyaryl groups in the spectra of hydrolyzed lignin corresponds to the increase in intensity of the C=C-bond stretching and deformation vibrational bands. The increase in the auxochromic effect of the double bonds adjacent to the aromatic ring is seen in the increase in the absorption in the near-ultraviolet and visible light ranges. The biochemical preparation of the raw material led to disappearance of the IR bands for the double bonds in the carbonyl and alkene groups accompanied by a 1.5–2-fold enhancement of the absorption of alkyl hydroxyl groups and a 3–4-fold enhancement of the absorption of the hydroxyl group in the hydroxyaryl units. These results are consistent with the analytical data obtained upon biomodified preparation by the differential UV spectroscopic method and indicate greater photostabilizing capacity of lignin combined with absolute transparency in the visible range.

The reported methods and data for the synthesis and reactivity of electron-deficient 3-vinylchromones containing electron-withdrawing­ groups at the exo-cyclic double bond are summarized and systematized for the first time. The main methods for obtaining these compounds are Knoevenagel condensation, Wittig reaction, and palladium-catalyzed cross-couplings. The most important chemical properties are transformations under the action of mono- and dinucleophiles, ambiphilic cyclizations, and cycloaddition reactions. The cross-conjugated and polyelectrophilic dienone system in 3-vinylchromones provides their high reactivity and makes these compounds valuable building blocks for the preparation of more complex heterocyclic systems. Chemical transformations of 3-vinylchromones usually begin with an attack of the C-2 atom and are accompanied by the opening of the pyrone ring followed by recyclization, in which the carbonyl group of chromone, an exo-double bond or a substituent on it can take part. The mechanisms of the reactions are discussed, the conditions for their implementation are described, and the yields of the resulting products are given. This review focuses on an analysis and generalization of the knowledge that has accumulated on the chemistry of electron-deficient 3-vinylchromones, mostly over the past 15 years.1 Introduction2 Synthesis of 3-Vinylchromones3 Reactions with Mononucleophiles4 Reactions with Dinucleophiles5 Ambiphilic Cyclization6 Cycloaddition Reactions7 Other Reactions8 Conclusion

Single crystal X-ray (sc XRD) analyses of three symmetrically substituted cyclopentadienyl radicals (1, 2, 5) containing sterically demanding aryl groups showed that they crystallize as discrete valence tautomers (Jahn-Teller distortion) in the solid state with the unpaired electron either located in the b1 orbital (type I, state 2B1), resulting in a localized radical with two adjacent double bonds, or the a2 orbital (type II, state 2A2), leading to an allyl-type radical. Their properties in solution were examined by EPR spectroscopy as well as cyclovoltammetry and UV/vis spectroscopy including two additional cyclopentadienyl radicals (1-5). The electronic nature of 1-5 was further investigated by quantum chemical calculations.

Presented herein is a novel and efficient α-C(sp3)-H alkenylation of cyclic amines with maleimides. Mechanistically, this C(sp3)-H/C(sp2)-H cross dehydrogenative coupling (CDC) reaction involves a cascade procedure including oxidative α-amino radical formation from the cyclic amine substrate and nucleophilic addition of the in situ formed α-amino radical onto the electron-deficient carbon-carbon double bond of maleimide followed by oxidation and β-elimination. Notably, this direct α-functionalization provides an effective alternative to the conventional ionic reaction mode, in which an imine or iminium intermediate is formed to react with electron-rich coupling partners other than electron-deficient ones. In general, this method features readily available and structurally diverse substrates, a green and economical catalyst, a unique reaction pathway, mild reaction conditions, high efficiency, and excellent atom economy. This new reaction enriches the application of Fe(III)-catalyzed C(sp3)-H activation and functionalization.