Different Schiff Bases—Structure, Importance and Classification

Molecules, Journal Year: 2022, Volume and Issue: 27(3), P. 787 - 787

Published: Jan. 25, 2022

Schiff bases are a vast group of compounds characterized by the presence double bond linking carbon and nitrogen atoms, versatility which is generated in many ways to combine variety alkyl or aryl substituents. Compounds this type both found nature synthesized laboratory. For years, have been greatly inspiring chemists biochemists. In article, we attempt present new take on compounds, underlining importance various types bases. Among different that can be classified as bases, chose hydrazides, dihydrazides, hydrazones mixed derivatives such hydrazide–hydrazones. these presented elements their structure allow them While typical examples including hydrazides among may surprising for some. case, possible due amide-iminol tautomerism. The carbon–nitrogen iminol tautomer element addition characteristics selected derivatives, sometimes classification, literature items which, our opinion, represent fields well.

Language: Английский

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Palladium-Catalyzed Difluorocarbene Transfer Enabled Divergent Synthesis of γ-Butenolides and Ynones from Iodobenzene and Terminal Alkynes

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(2), P. 1722 - 1731

Published: Jan. 4, 2024

Herein, we report a ligand-controlled palladium-catalyzed method that enables the synthesis of ynones and γ-butenolides with excellent regioselectivity from same set readily available aryl iodides, acetylenes, BrCF2CO2K. In this reaction, [PdII]═CF2 does demonstrate electrophilicity can generate CO when reacting H2O. It is environmentally friendly safe compared to traditional methods, current protocol us afford in high yields functionality tolerance. Moreover, esters also be obtained corresponding phenols alcohols utilizing strategy. The success late-stage functionalization bioactive compounds further illustrates synthetic utility material development drug discovery.

Language: Английский

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Multi-objective goal-directed optimization of de novo stable organic radicals for aqueous redox flow batteries

Nature Machine Intelligence, Journal Year: 2022, Volume and Issue: 4(8), P. 720 - 730

Published: Aug. 4, 2022

Abstract Advances in the field of goal-directed molecular optimization offer promise finding feasible candidates for even most challenging design applications. One example a fundamental challenge is search novel stable radical scaffolds an aqueous redox flow battery that simultaneously satisfy requirements at anode and cathode, as relatively few organic radicals are known to exist. To meet this challenge, we develop new open-source framework based on AlphaZero coupled with fast, machine-learning-derived surrogate objective trained nearly 100,000 quantum chemistry simulations. The function comprises two graph neural networks: one predicts adiabatic oxidation reduction potentials second electron density local three-dimensional environment, previously shown be correlated persistence stability. With no hard-coded knowledge chemistry, reinforcement learning agent finds molecule precise combination redox, stability synthesizability defined level, many which have reasonable predicted retrosynthetic pathways. optimized molecules show alternative may unique profile enable low-cost symmetric batteries.

Language: Английский

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Tuning the Electronic Properties of Main-Group Species by N-Heterocyclic Vinyl (NHV) Scaffolds

Accounts of Chemical Research, Journal Year: 2022, Volume and Issue: 55(3), P. 457 - 470

Published: Jan. 18, 2022

ConspectusMolecules and materials with easily tunable electronic structures properties are at the forefront of contemporary research. π-Conjugation is fundamental in organic chemistry plays a key role design molecular materials. In this Account, we showcase applicability N-heterocyclic vinyl (NHV) substituents based on classical carbenes (NHCs) for tuning structure, properties, stability main-group species (E) via π-conjugation and/or π-donation.NHVs such as [(NHC)═CR] (R = H or aryl) monoanionic ligands formally derived by deprotonation olefins (NHOs), (NHC)═CHR. Further H) viable, giving rise to vinylidene (NHVD) (NHC)═C. NHVs NHVDs feature highly polarizable exocyclic CNHC═C bond because presence adjacent π-donor nitrogen atoms. The nature NHC, particular π-acceptor property, has direct consequence polarity hence magnitude molecules. Thus, especially energy shape frontier orbitals, HOMO LUMO, can be fine-tuned judicious choice carbene unit. For instance, diphosphenes (RP═PR) alkyl invariably phosphorus lone-pair orbital, while P═P π-bond - 1 2. strong contrast, divinyldiphosphenes NHV) mainly π-bond. This owing π-conjugation, resulting lowering LUMO raising energy. They have remarkably small HOMO-LUMO gap (4.15-4.50 eV) readily undergo 1e-oxidations, stable radical cations dications.By employing similar approach, one access divinyldiarsenes corresponding dications crystalline solids. use promising stabilization metalloradicals been shown. By logical selection singlet carbenes, 2-phosha-1,3-butadiene 2-arsa-1,3-butadiene compounds, well related dications, prepared solids.The relevance NHV potent π-donors demonstrated elusive electrophilic phosphinidene arsinidene complexes {(NHV)E}Fe(CO)4 (E P As). Moreover, diradicaloid [(NHC)CP]2 p-quinodimethane derivatives [(NHC)CP2]2 an NHVD framework accessible solids.In special emphasis given contributions from laboratory. author hopes that Account will serve useful reference guide researchers interested studying applying scaffolds modern sciences.

Language: Английский

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Palladium(0) π-Lewis Base Catalysis: Concept and Development

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(10), P. 6422 - 6437

Published: March 1, 2024

The development of a new catalytic strategy plays vital role in modern organic chemistry since it permits bond formation an unprecedented and more efficient manner. Although the application preformed metal complexes as π-base-activated reagents have enabled diverse transformations elegantly, concept by directly utilizing transition metals π-Lewis base catalysts remain underdeveloped, especially field asymmetric catalysis. Here, we outline our perspective on discovery palladium(0) catalyst, which is capable increasing highest occupied molecular orbital (HOMO) energy both electron-neutral electron-deficient 1,3-dienes 1,3-enynes upon flexible η2-complexes formed situ resultant π-backdonation. Thus, fruitful carbon–carbon-forming reactions with electrophiles can be achieved enantioselectively vinylogous addition pattern, conceptually different from classical oxidative cyclization mechanism. Emphasis will given to mechanism elucidation, features, reaction design together further this emerging field.

Language: Английский

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Design and Development of Carbene-Catalyzed Intramolecular Vinylogous Stetter Reaction to Access Phenanthrol Derivatives

The Journal of Organic Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: March 4, 2025

The present study reveals the design and development of an N-heterocyclic carbene (NHC)-catalyzed intramolecular vinylogous Stetter reaction. This protocol enabled synthesis diverse phenanthrol derivatives naphthol-fused heterocycles in very good to excellent yields. success title reaction relies on biaryl aldehydes bearing p-quinone methide (p-QM) moiety that acts as a (1,6-conjugate) acceptor while aldehyde functional group serves acyl anion equivalent, generated situ from NHC-catalyzed umpolung. Salient features presented include atom efficiency, operational simplicity, broad substrate scope, large-scale synthesis, postsynthetic modifications.

Language: Английский

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Vinylogous Anionic Ring-Opening Polymerization of Vinylidenecyclopropanes with Native C–H Bonds as the Dormant Species

Journal of the American Chemical Society, Journal Year: 2025, Volume and Issue: 147(9), P. 7196 - 7202

Published: Feb. 24, 2025

Since its inception in 2023, the concept of "C-H bonds as dormant species" to control chain growth has emerged a promising, though still evolving, strategy for precision polymer synthesis. Beyond offering simpler polymerization method, this is expected promote unprecedented reaction pathways. In study, we report first vinylogous anionic ring-opening (ROP) vinylidenecyclopropanes. Cooperative La(OTf)3/DBU catalysis, conjunction with various sp3 and sp2 C-H bonds, streamlined synthesis well-defined alkyne polymers, which are amenable further chemical modifications. Control experiments density functional theory (DFT) calculations provide insights into origin selectivity role reversible-deactivation equilibrium.

Language: Английский

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Deconjugated butenolide: a versatile building block for asymmetric catalysis

Chemical Society Reviews, Journal Year: 2020, Volume and Issue: 49(18), P. 6755 - 6788

Published: Jan. 1, 2020

Deconjugated butenolides have emerged as a popular synthon for the enantioselective synthesis of γ-lactones. This review provides comprehensive overview on catalytic asymmetric reactions deconjugated reported till date.

Language: Английский

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Divergent Synthesis of [3,4]-Fused 3-Alkenyl-Oxindoles via Propargyl Alcohol-Triggered C(sp³)–H Functionalization

ACS Catalysis, Journal Year: 2021, Volume and Issue: 12(2), P. 943 - 952

Published: Dec. 30, 2021

[3,4]-Fused oxindoles are the core structures of naturally occurring oxindole alkaloids, and fused tricyclic have distinguished themselves with unique biological activities. Herein, we developed a synthetic strategy for divergent synthesis diverse types [3,4]-seven- or six-membered ring-fused 3-alkenyl-oxindoles incorporating benzazepine significant building blocks from propargyl alcohols via cascade nucleophilic substitution/site-selective hydride transfer/cyclization process unprecedentedly. In addition, variety nucleophiles, including H2O, were available controllable construction wide range conjugated alkenes, ketones, allyl encompassing natural products pharmaceutical motifs utilization 4-amine substituted isatins widespread terminal alkyne-derived alcohols. Furthermore, utility methodology mechanistic studies also well presented.

Language: Английский

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Regio‐ and Stereoselective Cascade of β,γ‐Unsaturated Ketones by Dipeptided Phosphonium Salt Catalysis: Stereospecific Construction of Dihydrofuro‐Fused [2,3‐b] Skeletons

Angewandte Chemie International Edition, Journal Year: 2021, Volume and Issue: 60(36), P. 19860 - 19870

Published: July 2, 2021

Abstract Chiral (dihydro)furo‐fused heterocycles are significant structural motifs in numerous natural products, functional materials and pharmaceuticals. Therefore, developing efficient methods for preparing compounds with these privileged scaffolds is an important endeavor synthetic chemistry. Herein, we develop effective, modular method by a dipeptide‐phosphonium salt‐catalyzed regio‐ stereoselective cascade reaction of readily available linear β,γ‐unsaturated ketones aromatic alkenes, affording wide variety structurally fused heterocyclic molecules high yields excellent stereoselectivities. Moreover, mechanistic investigations revealed that the bifunctional phosphonium salt controlled stereoselectivities this reaction, particularly proceeding through initial ketone α‐addition followed O ‐participated substitution; multiple hydrogen‐bonding interactions between Brønsted acid moieties catalyst nitro group alkene were crucial asymmetric induction. Given generality, versatility, efficiency method, anticipate it will have broad utilities.

Language: Английский

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