sn-2

This study focused on synthesizing the tricyclic hexasubstituted spirocyclopropane-core framework 2 of cyclohelminthol X ( 1 ), an antifungal cytotoxin isolated from Helminthosporium velutinum yone96 in a stereoselective manner. The synthesis features an SN 2-type cyclopropanation of the quaternary chloride 23 generated via a retro-Michael-type ring-opening reaction of an 8-azatricyclo[4.3.0.12,5 ]deca-3,7,9-trione derivative 22 . The successful synthesis confirmed the structure of 1 , resolving the ambiguity from the absence of X-ray crystallographic analysis...

Tin-lead (Sn-Pb) mixed perovskite with a narrow bandgap is an ideal candidate for single-junction solar cells approaching the Shockley-Queisser limit. However, due to the easy oxidation of Sn2+ , the efficiency and stability of Sn-Pb mixed perovskite solar cells (PSCs) still lag far behind that of Pb-based solar cells. Herein, highly efficient and stable FA0.5 MA0.5 Pb0.5 Sn0.5 I0.47 Br0.03 compositional PSCs are achieved by introducing an appropriate amount of multifunctional Tin (II) oxalate (SnC2 O4 ). SnC2 O4  with compensative Sn2+ and reductive oxalate group C2 O4 2- effectively passivates the cation and anion defects simultaneously, thereby leading to more n-type perovskite films...

Capturing gaseous mercury (Hg0 ) from sulfur dioxide (SO2 )-containing flue gases remains a common yet persistently challenge. Here we introduce a low-temperature sulfur chemical vapor deposition (S-CVD) technique that effectively converts SO2 , with intermittently introduced H2 S, into deposited sulfur (Sd 0 ) on metal sulfides (MS), facilitating self-sustained adsorption of Hg0 . ZnS, as a representative MS model, undergoes a decrease in the coordination number of Zn-S from 3.9 to 3.5 after Sd 0 deposition, accompanied by the generation of unsaturated-coordinated polysulfide species (Sn 2- , named Sd * ) with significantly enhanced Hg0 adsorption performance...

Sn-2 palmitate is widely used in infant formula. However, little is known about its effects on metabolism and body composition in middle-aged and elderly adults. In a double-blinded, randomized controlled trial, we enrolled Chinese adults aged 45-75 years with self-reported constipation. Individuals were randomly assigned in a 1:1 ratio to a 1,3-dioleoyl-2-palmitoyl-glycerol (OPO)-enriched oil (66% palmitic acid in the sn-2 position) or a control vegetable oil (24% palmitic acid in the sn-2 position) daily for 24 weeks...

The design of novel 4'-thionucleoside analogues bearing a C2' stereogenic all-carbon quaternary center is described. The synthesis involves a highly diastereoselective Mukaiyama aldol reaction, and a diastereoselective radical-based vinyl group transfer to generate the all-carbon stereogenic C2' center, along with different approaches to control the selectivity of the N -glycosidic bond. Intramolecular SN 2-like cyclization of a mixture of acyclic thioaminals provided analogues with a pyrimidine nucleobase...

This report demonstrates the first asymmetric synthesis of enantiopure structured triacylglycerols (TAGs) of the ABC type presenting three non-identical fatty acids, two of which are unsaturated. The unsaturated fatty acids included monounsaturated oleic acid (C18:1 n-9) and polyunsaturated linoleic acid (C18:2 n-6). This was accomplished by a six-step chemoenzymatic approach starting from ( R )- and ( S )-solketals. The highly regioselective immobilized Candida antarctica lipase (CAL-B) played a crucial role in the regiocontrol of the synthesis...

This study investigated the incorporation of nervonic acid into the chemical structure of phosphatidylcholine via a lipase-catalyzed acidolysis reaction to obtain a functional phospholipid. Lipase immobilization was conducted, and Amberlite XAD7-HP was selected as a carrier to immobilize phospholipase A1 (PLA1 ) for subsequent experiments. The main acidolysis reaction parameters, including enzyme load, substrate ratio, temperature, and water content, were studied against the reaction time. The optimum reaction conditions obtained were enzyme load, 20%; reaction temperature, 55 °C; water content, 1%; and reaction time, 9 h...

This study explores the innovative field of pulsed direct current arc-induced nanoelectrospray ionization mass spectrometry (DCAI-nano-ESI-MS), which utilizes a low-temperature direct current (DC) arc to induce ESI during MS analyses. By employing a 15 kV output voltage, the DCAI-nano-ESI source effectively identifies various biological molecules, including angiotensin II, bradykinin, cytochrome C, and soybean lecithin, showcasing impressive analyte signals and facilitating multicharge MS in positive- and negative-ion modes...

Peroxiredoxin 6 (Prdx6) repairs peroxidized membranes by reducing oxidized phospholipids, and by replacing oxidized sn-2 fatty acyl groups through hydrolysis/reacylation by its phospholipase A2 (aiPLA2 ) and lysophosphatidylcholine acyltransferase activities. Prdx6 is highly expressed in the lung, and intact lungs and cells null for Prdx6 or with single-point mutations that inactivate either Prdx6-peroxidase or aiPLA2 activity alone exhibit decreased viability, increased lipid peroxidation, and incomplete repair when exposed to paraquat, hyperoxia, or organic peroxides...

Nonenzymatic template-directed RNA copying requires catalysis by divalent metal ions. The primer extension reaction involves the attack of the primer 3'-hydroxyl on the adjacent phosphate of a 5'-5'-imidazolium-bridged dinucleotide substrate. However, the nature of the interaction of the catalytic metal ion with the reaction center remains unclear. To explore the coordination of the catalytic metal ion with the imidazolium-bridged dinucleotide substrate, we examined catalysis by oxophilic and thiophilic metal ions with both diastereomers of phosphorothioate-modified substrates...

An efficient one-pot method is proposed for the synthesis of 2-aroylbenzo[ b ]thiophen-3-ols from 2-mercaptobenzoic acid and various substituted aryl bromomethyl ketones in the presence of triethylamine. The reaction is likely to proceed through SN 2-type nucleophilic attack of the sulfhydryl group in thiosalicylic acid on bromomethyl ketone in the presence of a base to afford sulfanylbenzoic acid, which undergoes an intramolecular cyclization in situ to furnish 2-aroylbenzo[ b ]thiophen-3-ol in high yield...

Total synthesis of melognine was accomplished. A 10-membered cyclic alkyne was prepared via an intramolecular SN 2 reaction of a nosylamide. Enyne metathesis of the cyclic alkyne under an atmosphere of ethylene afforded a 1,3-diene. Intramolecular cycloaddition of a nitrone and an azomethine ylide with the 1,3-diene moiety constructed the characteristic highly fused skeleton. Further transformation, including ring-closing metathesis, resulted in the synthesis of melognine, whose NMR spectra did not match the reported data...

Thiols can react with readily available organic substrates under benign conditions, making them suitable for use in chemical, biological, physical, and materials and engineering research areas. In particular, the highly efficient thiol-based click reaction includes the reaction of radicals with electron-rich enes, Michael addition with electron-poor enes, carbonyl addition with isocyanate SN 2 ring opening with epoxies, and SN 2 nucleophilic substitution with halogens. This mini review provides insights into emerging venues for their industrial applications, especially for the applications of thiol-ene, thiol-isocyanate, and thiol-epoxy reactions, highlighting a brief chemistry of thiols as well as various approaches to polythiol synthesis...

We have quantum chemically investigated how microsolvation affects the various E2 and SN 2 pathways, their mutual competition, and the α-effect of the model reaction system HOO- (H2 O) n + CH3 CH2 Cl, at the CCSD(T) level. Interestingly, we identify the dual nature of the α-nucleophile HOO- which, upon solvation, is in equilibrium with HO- . This solvent-induced dual appearance gives rise to a rich network of competing reaction channels. Among both nucleophiles, SN 2 is always favored over E2, and this preference increases upon increasing microsolvation...

A detailed computational mechanistic study of the copper-catalysed three-component-type electrophilic carboamination of terminal alkynes with benzyne and an archetypal O -benzoylhydroxylamine electrophile is presented. Probing various plausible pathways for relevant elementary steps and scrutinising performance degradation pathways, with the aid of a reliable computational protocol applied to a realistic catalyst model combined with kinetic analysis, identified the pathways preferably traversed in productive catalysis...

The microsolvated anions HO- (NH3 ) n were found to induce new nucleophile NH2 - (H2 O)(NH3 ) n -1 via intramolecular proton transfer. Hence, the ion-molecule nucleophilic substitution (SN 2) reaction between CH3 Cl and these shapeshifting nucleophiles lead to both the HO- path and NH2 - path, meaning that the respective attacking nucleophile is HO- or NH2 - . The CCSD(T) level of calculation was performed to characterize the potential energy surfaces. Calculations indicate that the HO - species are lower in energy than the NH2 - species, and the SN 2 reaction barriers are lower for the HO- path than the NH2 - -path...

It has been theoretically predicted that perturbation of the Berry curvature by electromagnetic fields gives rise to intrinsic nonlinear anomalous Hall effects that are independent of scattering. Two types of nonlinear anomalous Hall effects are expected. The electric nonlinear Hall effect has recently begun to receive attention, while very few studies are concerned with the magneto-nonlinear Hall effect. Here, we combine experiment and first-principles calculations to show that the kagome ferromagnet Fe_{3}Sn_{2} displays such a magneto-nonlinear Hall effect...

Bimolecular substitution reactions involving N as the central atom have continuously improved our understanding of substitution dynamics. This work used chemical dynamics simulations to investigate the dynamics of NH2 Cl with N as the central atom and the multiatomic nucleophile CH3 O- and compared these results with the F- + NH2 Cl reaction. The most noteworthy difference is in the competition between proton transfer (PT) and the SN 2 pathways. Our results demonstrate that, for the CH3 O- + NH2 Cl system, the PT pathway is considerably more favorable than the SN 2 pathway...

A two-dimensional (2D) ferroelectric semiconductor, which is coupled with photosensitivity and room-temperature ferroelectricity, provides the possibility of coordinated conductance modulation by both electric field and light illumination and is promising for triggering the revolution of optoelectronics for monolithic multifunctional integration. Here, we report that semiconducting Sn2 P2 S6 crystals can be achieved in a 2D morphology using a chemical vapor transport approach with the assistant of space confinement and experimentally demonstrate the robust ferroelectricity in atomic-thin Sn2 P2 S6 nanosheet at room temperature...

Experiments have suggested that strong interactions between molecular ensembles and infrared microcavities can be employed to control chemical equilibria. Nevertheless, the primary mechanism and key features of the effect remain largely unexplored. In this work, we develop a theory of chemical equilibrium in optical microcavities, which allows us to relate the equilibrium composition of a mixture in different electromagnetic environments. Our theory shows that in planar microcavities under strong coupling with polyatomic molecules, hybrid modes formed between all dipole-active vibrations and cavity resonances contribute to polariton-assisted chemical equilibrium shifts...