Migration Of Group Research Articles

Alkylcyanation of Unactivated Alkenes with Protic C(sp3)−H Feedstocks via Radical‐Initiated Intramolecular Cyano Group Migration Enabled by Photoredox/Brønsted Base Dual Catalysis

AbstractCyanofunctionalization of alkenes via radical‐initiated cyano migration was a straightforward pathway to access alkyl nitriles. Herein, By the synergistic merger of photoredox catalysis and Brønsted base catalysis, a mild protocol of alkylcyanation of unactivated alkenes with protic C(sp3)−H feedstocks via intramolecular 1,4‐cyano group migration was reported. This method was enabled in an atom‐, and step‐economy manner, delivering a series of γ‐cyanoester derivatives in moderate to excellent yields.

Ag-Catalyzed Cyclization-Intermolecular Sulfinyl Group Transfer Cascade Reactions Enabling Enantioselective Synthesis of 4-Sulfinylisoquinolines.

N-Sulfinylimines derived from ortho-alkynylbenzaldehydes were efficiently converted into the corresponding 4-sulfinylisoquinolines in good to excellent yields. The reaction proceeds via cyclization followed by intermolecular migration of the sulfinyl group from the nitrogen atom to the silver-bound carbon of the resulting cyclized vinylsilver intermediate with the aid of either a counteranion or a nucleophilic species. Moreover, the Ag-catalyzed reaction in the presence of quinidine acetate as a chiral nucleophilic cocatalyst yielded chiral isoquinolines with high enantioselectivities through a dynamic kinetic asymmetric transformation (DYKAT).

Interception of Alkynyl Tetracoordinate Borons with Sulfur Electrophiles beyond the Zweifel Pathway

AbstractZweifel reaction is a powerful strategy to construct olefins from alkenyl tetracoordinate borons in organoboron chemistry, however, it usually only involves one functional group migration and then undergoes an elimination process affording alkenes or alkynes exclusively. Herein, we disclose several intriguing interception of alkynyl tetracoordinate borons with sulfur electrophiles. Wherein, the substituted benzothiophenes are accessed by consecutive 1,2‐migrations and intramolecular electrophilic substitution, meanwhile, the challenging and elusive five/four‐membered boracycles are easily assembled, and an approach to alkenyl sulfides with good stereoselectivity was developed as well. Moreover, by adding readily available deuterium sources, the tetrasubstituted deuterated alkenyl sulfides with high deuteration rates are constructed. These protocols not only improve atom economy by prohibiting the elimination of Zweifel intermediate, but also enrich the reaction modes of alkynyl tetracoordinate borons achieving versatile value‐added sulfur‐containing molecules. Mechanistic investigations illustrate that dichlorosulfoxide (SOCl2) and dialkylaminosulfur trifluoride‐type reagents (DAST‐type) as surfur sources could promote dual 1,2‐aryl migration of alkynyl tetracoordinate borons, which are distinct from traditional Zweifel reaction, and the regulation of steric hindrance could also make four‐membered boracycles and alkenyl sulfides feasible. And these transformations feature novel reaction modes and unusual reaction mechanisms with valuable products in high efficiency.

Hydroxyl-Assisted and Co(III)-Catalyzed Redox-Neutral C-H Activation/Directing Group Migration of 2-Pyridones with Propargyl Alcohols: Synthesis of Tetrasubstituted Alkenes.

This study provides a practical route to synthesize tetrasubstituted alkenes that involves Co(III)-catalyzed C-H bond activation and regioselective insertion of the alkyne, followed by chelation of the substrate hydroxyl to Co and migration of the pyridine group. Density functional theory studies revealed the origin of regioselectivity and elucidated the crucial role of the hydroxyl group for the migration of pyridine. The method can be conducted on a gram scale, is compatible with a wide range of substrates, and has a high functional group tolerance. To demonstrate its significance, the method was used for the late-stage modification of Fasudil. Furthermore, the synthetic significance of the method was demonstrated by the various derivatizations of the products, many of which exhibit intriguing fluorescence characteristics.

Interception of Alkynyl Tetracoordinate Borons with Sulfur Electrophiles beyond the Zweifel Pathway.

Zweifel reaction is a powerful strategy to construct olefins from alkenyl tetracoordinate borons in organoboron chemistry, however, it usually only involves one functional group migration and then undergoes an elimination process affording alkenes or alkynes exclusively. Herein, we disclose several intriguing interception of alkynyl tetracoordinate borons with sulfur electrophiles. Wherein, the substituted benzothiophenes are accessed by consecutive 1,2-migrations and intramolecular electrophilic substitution, meanwhile, the challenging and elusive five/four-membered boracycles are easily assembled, and an approach to alkenyl sulfides with good stereoselectivity was developed as well. Moreover, by adding readily available deuterium sources, the tetrasubstituted deuterated alkenyl sulfides with high deuteration rates are constructed. These protocols not only improve atom economy by prohibiting the elimination of Zweifel intermediate, but also enrich the reaction modes of alkynyl tetracoordinate borons achieving versatile value-added sulfur-containing molecules. Mechanistic investigations illustrate that dichlorosulfoxide (SOCl2) and dialkylaminosulfur trifluoride-type reagents (DAST-type) as surfur sources could promote dual 1,2-aryl migration of alkynyl tetracoordinate borons, which are distinct from traditional Zweifel reaction, and the regulation of steric hindrance could also make four-membered boracycles and alkenyl sulfides feasible. And these transformations feature novel reaction modes and unusual reaction mechanisms with valuable products in high efficiency.

Metal‐Free Nitration of Indazoles with tert‐Butyl Nitrile in Air to Prepare 3‐Nitroindazoles and 3‐Aminoindazoles

Comprehensive SummaryA variety of 3‐nitroindazoles and 3‐aminoindazoles were prepared in good to excellent yields with high regioselectivity through TBN‐mediated nitration at the C3‐position of indazoles under the air conditions and sequential reduction. Mechanistic studies revealed that TBN played crucial roles to produce •NO2 radical source in the presence of air conditions and C3‐nitration of indazoles was initiated by N1‐nitration and sequential migration of NO2 group to C3‐position. Moreover, this method could be easily applied in the gram scalable synthesis of ibuprofen and ciprofibrate‐derived 3‐aminoindazoles. The present method highlights air as mild oxidant, metal‐free radical nitration of indazole, N—N bond formation and cleavage, and late‐stage modification of drugs.

Migration of para-Nitrophenyl Groups in Methyl Pyranosides: Configuration and Conformation Determine the Kinetics.

para-Nitrophenyl (PNP) ethers of glycosides are important building blocks en route to functional carbohydrates. They are stable in neutral media, however, under basic conditions such as during the Zemplén deacylation of sugars, aryl migration is frequently observed. We have employed a library of O-PNP-substituted methyl glycosides of the manno-, galacto-, gluco- and altro-series to study the kinetics of aryl migration in MeOH/sodium methoxide using NMR spectroscopy revealing that migration between cis-oriented OH groups is faster than between trans-oriented ones. The rate constants of migration decrease in the order of Alt>Man>Gal>Glc and are related to the energy barriers of chair conformation inversion. The energy profile of the 3 to 4-PNP migration in methyl mannoside was calculated using DFT methods suggesting the Meisenheimer complex is an intermediate of PNP migration and that coordination of the sodium cation has a major impact on the energy profile.

Radical Copolymerization of 2‐Thiocyanatoethyl Substituted Acrylate to Introduce Thiol‐Acrylate‐Based Dynamic Bonds as Degradable Linker

ABSTRACTWe employ the 1,4‐cyano group migration radical polymerization strategy to copolymerize acrylates with 2‐thiocyanate ethyl substituted acrylates. The radical copolymerization can be effectively controlled using reversible addition−fragmentation chain‐transfer (RAFT) polymerization. This approach can incorporate thiol‐acrylate‐based dynamic bonds within the polymer main chain. Utilizing these dynamic bonds, we degrade the polymers under mild basic conditions, achieved with the assistance of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) to facilitate the reversible thiol‐Michael addition. Notably, high degradation efficiency is observed. This study exemplifies the application of 2‐thiocyanate ethyl substituted acrylate in radical copolymerization to produce degradable polymers.

Protective Effect of Resveratrol Against Non-Small Cell Lung Cancer: In-Vitro and In-Silico Studies

Resveratrol, a non-flavone polyphenol molecule, has been shown to be both chemotherapeutic and chemopreventive in the treatment of several forms of cancer, including lung cancer. 80% of cancers of the lungs are non-small cell lung cancers. The study was carried out to see the effects of Resveratrol in non-small cell lung cancer cells (A549) and to observe its binding as an inhibitor to Akt protein using in-vitro and in-silico studies, respectively. As per the results of Cell viability assay, which used Doxorubicin and Dexamethasone as standard drugs, Resveratrol (p = 0.01, p = 0.0051) could significantly stop lung cancer cells from growing, with IC50 values of 37.32 ± 0.8 μM. It was discovered that Resveratrol was about six times more effective than Dexamethasone, suggesting that it has a significantly higher anti-proliferative potential than this standard drug. During the Wound-closure assay, the rate of migration in the Resveratrol treatment group showed a lower migration rate at a higher concentration of 500 μM together with a change in the shape of the cell, demonstrating the concentration-dependent behavior of A549 cell growth. In the current study, it was demonstrated using Cell viability assay and Wound closure assay that Resveratrol exhibits anti-proliferative activity on A549 lung cancer cells and inhibits cancer cell proliferation in a concentration and time-dependent manner. It was also observed that Resveratrol binds to Akt protein and it inhibits the activity of Akt by interacting with the ATP-binding region of Akt protein. However, the molecular mechanism behind resveratrol’s anti-cancer benefits remains unknown. Finally, the current study may lay the groundwork for future research into the tumor suppressor resveratrol.

Radical Isomerization Homopolymerization of Linear α‐Olefins to Access C5, C6 or C7 Polymers

AbstractNon‐activated linear α‐olefins are valuable building blocks for organic transformation or olefin (co)polymerization, but they are recognized as textbook knowledge for non‐homopolymerizable monomers under radical conditions. In this article, we disclose our effort to achieve an unprecedented library of all carbon‐bonded sequence‐regulated polymers via radical isomerization homopolymerization of α‐olefin derivatives. The success of this distinctive polymerization is attributed to the remarkable efficiency and selectivity exhibited during the cyano group migration or hydrogen atom transfer, which is greatly enhanced by the precise engineering of their monomer structures. This polymerization process enables the elongation of polymer chains by five, six, or seven carbon atoms at each propagation step. These polymers, obtained through the cyano group migration or hydrogen atom transfer involved radical isomerization polymerization processes, emerge as promising candidates resembling polyethylene or polyacrylonitrile copolymers.

Radical Isomerization Homopolymerization of Linear α-Olefins to Access C5, C6 or C7 Polymers.

Non-activated linear α-olefins are valuable building blocks for organic transformation or olefin (co)polymerization, but they are recognized as textbook knowledge for non-homopolymerizable monomers under radical conditions. In this article, we disclose our effort to achieve an unprecedented library of all carbon-bonded sequence-regulated polymers via radical isomerization homopolymerization of α-olefin derivatives. The success of this distinctive polymerization is attributed to the remarkable efficiency and selectivity exhibited during the cyano group migration or hydrogen atom transfer, which is greatly enhanced by the precise engineering of their monomer structures. This polymerization process enables the elongation of polymer chains by five, six, or seven carbon atoms at each propagation step. These polymers, obtained through the cyano group migration or hydrogen atom transfer involved radical isomerization polymerization processes, emerge as promising candidates resembling polyethylene or polyacrylonitrile copolymers.

Photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophene-3(2H)-ones containing a terpyridine receptor

New photo- and ionochromic N-acylated 2-(aminomethylene)benzo[b]thiophen-3(2H)-ones containing a terpyridine receptor have been synthesized. They absorb in the visible region of the spectrum at 423–426 nm and exhibit emission at 463–468 nm. Their irradiation in acetonitrile with light of 436 nm leads to a multi-stage rearrangement, including Z/E isomerization about the CC bond, N → O migration of the acyl group and the formation of non-emissive O-acylated E-isomers, which were isolated preparatively. Their structure was established unambiguously by IR, 1H, 13C NMR spectroscopy and HR mass spectrometry. The reverse thermal reaction with O → N migration of the acyl group is catalyzed by acid catalysts. N-Acylated compounds in acetonitrile selectively form non-fluorescent complexes with Fe2+ cations, which is accompanied by the naked-eye effect with changing the color from yellow to maroon. A successful selective interaction with AcO− led to the restoration of the initial absorption and emission properties. Density functional theory (DFT)calculations at the M06-2X/def2-TZVP level with the PCM solvation method were used to explain the observed photoisomerizations and ionochromic transformations. The obtained compounds represent multifunctional on-off-on molecular switches of optical and fluorescent properties upon sequential exposure to light and H+ or sequential addition of Fe2+ and AcO− ions. A combinatorial logic gate was designed based on the basis of these switching properties.

Introduction: Exile and Innovation☆

AbstractThe early modern period was an age marked by the forced migration and displacement of social groups and individuals around the world. Huguenots, conversos, Catholics, cavaliers, Jacobites, and French emigrés alike fled or were expelled from their homes and communities. Yet, exile is still usually considered only within the context of broader religious or political events by scholars working in sub‐fields rather than as a phenomenon worthy of study in its own right. Foregrounding displacement as a major facet of early modern society and culture, this special issue explores the experience, perception, and poetics of exile from 1500 to 1800 through the prism of innovation. It encompasses displaced individuals and communities, as well as writings that treat the theme of exile, to consider how forced migration shaped the social, cultural, political, and intellectual contours of the era – and thus led to innovative practices and ideas.

Spontaneous acetyl group migration between xylose and arabinose in arabinoxylan-derived oligosaccharide

Previously, a synthetic β-1,4-xylooligosaccharide having the non-reducing-end xylopyranosyl residue both acetylated and arabinosylated was reported to undergo an acetyl group migration [Bella et al., 2023]. This process was further investigated in this work by NMR spectroscopy. It was found that the spontaneous transesterification reaction was regioselective involving the acetyl group transfer from position O-2 of the xylopyranosyl residue exclusively to position O-2 of the α-l-arabinofuranosyl moiety linked to position 3 of the same xylose. Finally, the acetyl group migration resulted in an equilibrium, where the arabinose 2-acetate predominated over the xylose 2-acetate. This is the first report of acetyl group migration between different pentoses, which are in addition, glycosidically interconnected. This intramolecular transacetylation may have significant consequences on the structure of acetylated fragments generated in arabinoxylan hydrolyzates. In turn, it can broaden enzyme repertoire related to biotechnological exploitation of the esterified arabinoxylan fragments, e.g., through its enzyme-catalyzed deesterification of 2-acetylated arabinose moiety.

Dearomative Functionalization of Activated Quinolines: Transfer Hydrogenation/Cycloaddition Cascade to Construct α‐Tertiary Amines

AbstractCascade dearomative functionalization is a robust protocol to convert flat arenes into medicinally relevant three‐dimensional architectures with added new functionality. Herein, a dearomative cycloaddition protocol for synthesizing tetrahydroquinoline‐embedded α‐tertiary amine scaffolds has been developed employing quinolinium salts and sulfonyl azides under metal‐free conditions. An underexplored and mechanistically distinct pathway is unveiled, creating quaternary‐center‐bearing amine skeletons by an amine group migration during the transfer hydrogenation and cycloaddition cascade reaction. This approach provided a broad substrate scope of α‐tertiary amine scaffolds from a plethora of C3‐substituted quinolinium and sulfonyl azides. The post‐synthetic modifications have further diversified the α‐tertiary amine core into interesting scaffolds. Preliminary mechanistic studies suggested the involvement of aziridine ring formation for the amine migration to the C‐3 position of quinoline to generate the α‐tertiary amine core.

Photoredox Catalyzed Conia-Ene-Type Cyclization/Smiles Rearrangement Cascade Reactions to Access Substituted Methylenecarbocycles.

We report a novel visible-light-driven photoredox-catalyzed cascade reaction involving Conia-ene-type cyclization and Smiles rearrangement initiated from alkyne-tethered α-sulfonyl esters. This methodology not only facilitates the rapid synthesis of a broad spectrum of highly substituted methylenecarbocycles but also introduces a new mechanistic pathway with aryl group migration, surpassing the conventional 1,5-hydrogen shift typically observed in Conia-ene reactions.

“A Colony to Themselves”: Scottish Highland Settler Colonialism in British North America, 1770–1804

Abstract This article explores the links between anti-Catholicism in the United Kingdom and the acceleration of settler colonialism in British North America, and it does so by considering two group migrations from Catholic districts in the North West Highlands and Islands of Scotland. Occurring over 30 years apart, the Glenaladale settlement (1772) in Prince Edward Island and the Glengarry settlement (1803) in Upper Canada offer instructive insight into how anti-Catholicism activated Highland Catholic colonial agency. Not only did significant numbers of Highland Catholics choose to quit Scotland forever, but their settlement in places like Prince Edward Island and Upper Canada accelerated the process of settler colonialism and the establishment of the Catholic Church. The colonies at Glengarry and Glenaladale were peopled by settlers who were doubly motivated to settle in the empire. They stood to prosper economically—certainly—and they also stood to gain the freedom to practice their faith free of obvious interference. To the Indigenous peoples whose ancestral lands they settled, the consequences were not softened by this pretext for settler colonization, and too often the history of anti-Catholic discrimination in the four nations elide the fact that Catholics were enthusiastic colonizers elsewhere, and that the two processes were often related.

Radical-triggered translocation of C-C double bond and functional group.

Multi-site functionalization of molecules provides a potent approach to accessing intricate compounds. However, simultaneous functionalization of the reactive site and the inert remote C(sp3)-H poses a formidable challenge, as chemical reactions conventionally occur at the most active site. In addition, achieving precise control over site selectivity for remote C(sp3)-H activation presents an additional hurdle. Here we report an alternative modular method for alkene difunctionalization, encompassing radical-triggered translocation of functional groups and remote C(sp3)-H desaturation via photo/cobalt dual catalysis. By systematically combining radical addition, functional group migration and cobalt-promoted hydrogen atom transfer, we successfully effectuate the translocation of the carbon-carbon double bond and another functional group with precise site selectivity and remarkable E/Z selectivity. This redox-neutral approach shows good compatibility with diverse fluoroalkyl and sulfonyl radical precursors, enabling the migration of benzoyloxy, acetoxy, formyl, cyano and heteroaryl groups. This protocol offers a resolution for the simultaneous transformation of manifold sites.

Norrish-Yang-type cyclopropanation via functional group migration with photosensitizer at ppb loading

Norrish-Yang-type cyclopropanation via functional group migration with photosensitizer at ppb loading

Triplet Energy Transfer (EnT)-Promoted 1,3-Dipolar Cycloaddition Reactions of N-(Trimethylsilyl)methylphthalimide with Electron-Deficient Alkynes and Alkenes.

Triplet energy transfer (EnT)-promoted photochemical pathways, arisen by visible light and its photosensitizers, have gained significant attention as a complementary strategy for initiating organic transformations in photochemical reactions that are unlikely to occur through a single electron transfer (SET) process. In the present study, we investigated the triplet EnT-promoted 1,3-dipolar cycloaddition reactions of N-(trimethylsilyl)methylphthalimide with electron-deficient alkynyl and alkenyl dipolarophiles. The triplet excited state of N-(trimethylsilyl)methylphthalimide, promoted by the triplet EnT from thioxanthone (TXA) photosensitizer, underwent sequential intramolecular SET and carbon-to-oxygen migration of the silyl group to form azomethine ylide. This generated ylide cycloadded to alkynes or alkenes to regioselectively and stereospecifically produce a nitrogen-containing benzopyrrolizidine scaffold with multiple stereogenic centers. Crucially, the stereoselectivity of these cycloaddition reactions (i.e., endo versus exo addition) was influenced by the nature of the dipolarophiles.