Subsequent Nucleophilic Reaction Research Articles

Bond Strength and Interaction Energies in Togni Reagents: Insights from Molecular Electrostatic Potential-Based Parameters.

Togni reagents and their analogs, classified as hypervalent iodine(III) complexes, serve as potent trifluoromethylation agents. The interplay of cis and trans factors plays a pivotal role in shaping their performance, affecting aspects such as bond strength, interaction energies, stability, and subsequent nucleophilic reactions. In this context, we propose the utilization of the molecular electrostatic potential (MESP) at the carbon atom (VC) of the I-CF3 moiety as a sensitive parameter to quantify the cis and trans influences in Togni-type reagents. Our study has shown that VC serves as a convenient probe for determining the heterolytic bond dissociation energy (BDE) and, consequently, assessing the reactivity of these reagents. Moreover, these parameters have been successfully applied to evaluate the strength of the σ-hole interactions with nucleophiles (Cl- and NMe3). Additionally, we provide insights into interactions of Togni reagents with Brønsted acids such as HCl and HSO3F, elucidating them in terms of MESP topological parameters. These findings yield valuable information about the electronic properties of hypervalent iodine reagents, particularly Togni-type reagents, offering the potential for optimizing structurally modified reagents with enhanced activity and stability.

Copper/Iodine‐Catalyzed Hydroxyamination of Alkenyl Keto Oximes Using DMSO as the Oxygen Atom Source and Medium

AbstractA new copper/I2‐catalyzed hydroxyamination of alkenes of unsaturated keto oximes with DMSO as the hydroxy oxygen atom source and medium for assembling 2‐(2‐hydroxyalkyl)‐3,4‐dihydro‐2H‐pyrrole 1‐oxides is described. Mechanistic studies suggest that the reaction is terminated by a single electron oxidation and subsequent nucleophilic reaction.

Versatile Palladium-Catalyzed Approach to Acyl Fluorides and Carbonylations by Combining Visible Light- and Ligand-Driven Operations.

We describe the development of a general palladium-catalyzed carbonylative method to synthesize acyl fluorides from aryl, heteroaryl, alkyl, and functionalized organic halides. Mechanistic analysis suggests that the reaction proceeds via the synergistic combination of visible light photoexcitation of Pd(0) to induce oxidative addition with a ligand-favored reductive elimination. These together create a unidirectional catalytic cycle that is uninhibited by the classical effect of carbon monoxide coordination. Coupling the catalytic formation of acyl fluorides with their subsequent nucleophilic reactions has opened a method to perform carbonylation reactions with unprecedented breadth, including the assembly of highly functionalized carbonyl-containing products.

A Competition between Hydrogen, Stacking, and Halogen Bonding in N-(4-((3-Methyl-1,4-dioxo-1,4-dihydronaphthalen-2-yl)selanyl)phenyl)acetamide: Structure, Hirshfeld Surface Analysis, 3D Energy Framework Approach, and DFT Calculation.

N-(4-((3-Methyl-1,4-dioxo-1,4-dihydronaphthalen-2-yl)selanyl)phenyl)acetamide (5), C19H15NO3Se, was prepared in two steps from 4,4′-diselanediyldianiline (3) via reduction and subsequent nucleophilic reaction with 2-methyl-3-bromo-1,4-naphthalenedione, followed by acetylation with acetic anhydride. The cytotoxicity was estimated against 158N and 158JP oligodendrocytes and the redox profile was also evaluated using different in vitro assays. The technique of single-crystal X-ray diffraction is used to confirm the structure of compound 5. The enantiopure 5 crystallizes in space group P21 with Flack parameter 0.017 (8), exhibiting a chiral layered absolute structure. Molecular structural studies showed that the crystal structure is foremost stabilized by N-H···O and relatively weak C-H···O contacts between molecules, and additionally stabilized by weak C-H···π and Se···N interactions. Hirshfeld surface analysis is used to quantitatively investigate the noncovalent interactions that stabilize crystal packing. Framework energy diagrams were used to graphically represent the stabilizing interaction energies for crystal packing. The analysis of the energy framework shows that the interactions energies of and C-H···π and C-O···π are primarily dispersive and are the crystal’s main important forces. Density functional theory (DFT) calculations were used to determine the compound’s stability, chemical reactivity, and other parameters by determining the HOMO-LUMO energy differences. The determination of its optimized surface of the molecular electrostatic potential (MEP) was also carried out. This study was conducted to demonstrate both the electron-rich and electron-poor sites.

ChemInform Abstract: One‐Pot Synthesis of Tetracyclic Fused Imidazo[1,2‐a]pyridines via a Three‐Component Reaction.

ChemInformVolume 47, Issue 38 Heterocyclic Compounds ChemInform Abstract: One-Pot Synthesis of Tetracyclic Fused Imidazo[1,2-a]pyridines via a Three-Component Reaction. Bo Yang, Bo Yang Sch. Chem. Biol. Biotechnol., Shenzhen Grad. Sch. Peking Univ., Shenzhen 518055, Peop. Rep. ChinaSearch for more papers by this authorChuanye Tao, Chuanye Tao Sch. Chem. Biol. Biotechnol., Shenzhen Grad. Sch. Peking Univ., Shenzhen 518055, Peop. Rep. ChinaSearch for more papers by this authorTaofeng Shao, Taofeng Shao Sch. Chem. Biol. Biotechnol., Shenzhen Grad. Sch. Peking Univ., Shenzhen 518055, Peop. Rep. ChinaSearch for more papers by this authorJianxian Gong, Jianxian Gong Sch. Chem. Biol. Biotechnol., Shenzhen Grad. Sch. Peking Univ., Shenzhen 518055, Peop. Rep. ChinaSearch for more papers by this authorChao Che, Chao Che Sch. Chem. Biol. Biotechnol., Shenzhen Grad. Sch. Peking Univ., Shenzhen 518055, Peop. Rep. ChinaSearch for more papers by this author Bo Yang, Bo Yang Sch. Chem. Biol. Biotechnol., Shenzhen Grad. Sch. Peking Univ., Shenzhen 518055, Peop. Rep. ChinaSearch for more papers by this authorChuanye Tao, Chuanye Tao Sch. Chem. Biol. Biotechnol., Shenzhen Grad. Sch. Peking Univ., Shenzhen 518055, Peop. Rep. ChinaSearch for more papers by this authorTaofeng Shao, Taofeng Shao Sch. Chem. Biol. Biotechnol., Shenzhen Grad. Sch. Peking Univ., Shenzhen 518055, Peop. Rep. ChinaSearch for more papers by this authorJianxian Gong, Jianxian Gong Sch. Chem. Biol. Biotechnol., Shenzhen Grad. Sch. Peking Univ., Shenzhen 518055, Peop. Rep. ChinaSearch for more papers by this authorChao Che, Chao Che Sch. Chem. Biol. Biotechnol., Shenzhen Grad. Sch. Peking Univ., Shenzhen 518055, Peop. Rep. ChinaSearch for more papers by this author First published: 01 September 2016 https://doi.org/10.1002/chin.201638171Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume47, Issue38September, 2016 RelatedInformation

One-pot synthesis of tetracyclic fused imidazo[1,2-a]pyridines via a three-component reaction.

A novel three-component reaction has been developed to assemble biologically and pharmaceutically important tetracyclic fused imidazo[1,2-a]pyridines in a one-pot fashion utilizing readily available 2-aminopyridines, isatins and isocyanides. The three-component coupling proceeds through the Groebke–Blackburn–Bienaymé reaction followed by a retro-aza-ene reaction and subsequent nucleophilic reaction of the in-situ generated imidazo[1,2-a]pyridines bearing an isocyanate functional group.

Acid Chloride Synthesis by the Palladium-Catalyzed Chlorocarbonylation of Aryl Bromides.

We report a palladium-catalyzed method to synthesize acid chlorides by the chlorocarbonylation of aryl bromides. Mechanistic studies suggest the combination of sterically encumbered PtBu3 and CO coordination to palladium can rapidly equilibrate the oxidative addition/reductive elimination of carbon-halogen bonds. This provides a useful method to assemble highly reactive acid chlorides from stable and available reagents, and can be coupled with subsequent nucleophilic reactions to generate new classes of carbonylated products.

Heterocyclic synthesis via catalysis of N-heterocyclic carbenes: very classical and very modern chemical species

Abstract After a long history of medical and biochemical investigations of vitamin B1, N-heterocyclic carbenes (NHCs) have recently been used as organocatalysts for a variety of synthetic reactions. This review article highlights the application of NHC-catalyzed reactions including enantioselective reactions to the heterocyclic synthesis. NHC-catalyzed benzoin condensation and Stetter reaction of ether- and amine-linked aldehydes give four- to six-membered oxygen and nitrogen heterocycles. NHC-catalyzed conjugate additions of enals to ketones and imines afford γ-lactones and γ-lactams. When the NHC-catalyzed reaction intermediates of enals are protonated, the reaction of the resulting enols with enones and ene-imines furnish formal hetero-Diels-Alder products. Acyl fluoride and esters can be activated by NHCs, and subsequent aldol and Michael reactions give β-lactones. Oxidation of intermediates derived from enals or the intermediates from ynals provide unsaturated acyl azolium which are transformed into cyclic products via subsequent nucleophilic reactions. NHCs also catalyze [2+2] cycloadditions of ketenes and other heterocumulenes and ring expansion of cyclic aldehydes.

A kinetic study of the high temperature rearrangement of 4‐ethyl‐3,5‐diphenyl‐4H‐1,2,4‐triazole

AbstractThe kinetics of the thermal rearrangement 4‐ethyl‐3,5‐diphenyl‐4H‐1,2,4‐triazoles, 1, to the corresponding 1‐ethyl‐3,5‐diphenyl‐1‐alkyl‐1H‐1,2,4‐triazoles, 2, was studied in 15‐Crown‐5 and octadecane at 330 °C. The reaction was very slow in octadecane but proceed well in 15‐Crown‐5. The reaction order for the reaction was not constant but changed from an initial second order rate law towards a first order rate law as the reaction progressed. This was confirmed by the concentration dependent reaction order, nc, which was larger than the time dependent rate law, nt. The rationale for the observation was, that at high substrate concentrations the reaction order was second order while at lower concentrations a competing solvent assisted reaction plays an increasing important role. The data were in agreement with a mechanism in which the neutral 4‐alkyl‐triazoles in an intermolecular nucleophilic displacement reaction form a triazolium triazolate, which in a subsequent nucleophilic reaction gives the observed product.

Macroporous and hydrophilic polymer resins modified with isothiocyanate groups for immobilization of enzymes

Hydrophilic and macroporous polymer resins composed of glycerylmethacrylate, styrene, and divinylbenzene were quite easily modified with isothiocyanate groups using a Friedel-Crafts reaction with 3-chloropropionyl chloride and subsequent nucleophilic reaction with KSCN. Alkaline phosphatase and trypsin could be covalently bound to the isothiocyanate-carrying polymer resins, and the immobilized enzymes obtained were sufficiently active and stable due to a covalent bonding via a spacer group between the carrier resins and the enzymes and also due to a hydrophilic environment around the enzymes. A heterogeneity of the immobilized enzyme was taken into account to interpret the thermal denaturation process of the enzyme immobilized onto the resins.

Isothiocyanato‐substituted hydrophilic polymer beads for immobilization of enzymes

AbstractStyrene–glycidylmethacrylate–divinylbenzene resin beads could be converted to highly hydrophilic resin beads by acid treatment. These resin beads could be modified with isothiocyanato (NCS) groups quite easily using a Friedel–Crafts reaction and a subsequent nucleophilic reaction with KSCN. The resin beads substituted with NCS groups were useful as supports to immobilize enzymes, because they were not only hydrophilic but also bind proteins covalently. The enzymes immobilized onto the resin beads showed sufficiently high catalytic activities for a long period.