Synthesis of Quinolines through Three-Component Cascade Annulation of Aryl Diazonium Salts, Nitriles, and Alkynes

One-Pot Three-Component Reaction for the Synthesis of 3,4-Dihydroquinazolines and Quinazolin-4(3H)-ones

A highly efficient and straightforward one-pot synthesis of diversely substituted 3,4-dihydroquinazolines and quinazolin-4(3H)-ones has been achieved through a domino three-component assembly reaction of arenediazonium salts, nitriles, and bifunctional aniline derivatives. This new protocol involves three C-N bond formations through the initial formation of N-arylnitrilium intermediates from arenediazonium salts and nitriles, followed by the sequential nucleophilic addition and cyclization reactions with bifunctional anilines, leading to such N-heterocyclic compounds of biological and pharmacological importance. This method offers a simple, expedient, and robust approach with the use of amenable and easily accessible reactants/reagents under metal-free mild conditions, good functional group tolerance, and high efficiency. The synthetic applications were also demonstrated by derivatization of the products obtained from these processes and syntheses of a diverse range of valuable polycyclic N-heterocycles.

Recent advancement in the synthesis of quinoline derivatives via multicomponent reactions

The synthesis of quinoline derivatives through multicomponent reactions (MCRs) has emerged as an efficient and versatile strategy in organic synthesis. MCRs offer the advantage of constructing complex molecular architectures in a single step, utilising multiple starting materials in a convergent manner. This review provides an overview of recent advancements in the field of quinoline synthesis via MCRs. Various MCRs, such as the Povarov reaction, the Gewald reaction, and the Ugi reaction have been successfully employed for the synthesis of diverse quinoline scaffolds. These methodologies not only showcase high atom economy but also allow the incorporation of structural diversity into the final products. The versatility of MCRs enables the introduction of functional groups and substitution patterns tailored to specific applications. This review highlights the significance of quinoline derivatives in medicinal chemistry, materials science, and other interdisciplinary areas. The continuous innovation and development of novel MCR-based approaches for quinoline synthesis hold great promise for the rapid and efficient generation of valuable compounds with a wide range of biological and physicochemical properties.

Photo-triggered C-arylation of active-methylene compounds with diazonium salts via an electron donor-acceptor (EDA) complex

The elucidation of the C-arylation of active methylene compounds under visible light conditions without a photocatalyst presents an intellectual challenge. The photo-induced C-arylation of active methylene compounds via electron donor-acceptor (EDA) complexes shows a strategic path for the synthesis of pharmacologically relevant compounds. This expansive and efficacious methodology facilitates C-arylation under environmentally conscientious conditions, exhibiting exemplary compatibility with diverse functional groups and yielding numerous compounds. This environmentally sustainable transformation underscores the merits of the procedural simplicity and benign reaction conditions. Notably, all resultant products were judiciously derived from active methylene compounds and diazonium salts through the intermediacy of the EDA complex.

One-Pot Synthesis of α-Amino Bisphosphonates from Nitriles via Tf2O/HC(OR)3-Mediated Interrupted Ritter-Type Reaction

A versatile synthesis of α-amino bisphosphonates has been achieved through one-pot interrupted Ritter-type reaction under mild conditions. The reactive Ritter intermediate nitrilium is in situ generated by treatment of nitrile with readily accessible Tf₂O/HC(OR¹)₃, which is trapped by phosphite ester to deliver the desired product. This protocol is efficient, scalable, and well compatible with a broad scope of substrates. In addition, plentiful characteristic J_P-C couplings including unusual five-bond long-range ⁵J_P-C and ³J_P-C across quaternary carbon and hetero (N) atoms were observed in ¹³C NMR spectra.

Iodine-imine Synergistic Promoted Povarov-Type Multicomponent Reaction for the Synthesis of 2,2'-Biquinolines and Their Application to a Copper/Ligand Catalytic System

An efficient iodine-imine synergistic promoted Povarov-type multicomponent reaction was reported for the synthesis of a practical 2,2'-biquinoline scaffold. The tandem annulation has reconciled iodination, Kornblum oxidation, and Povarov aromatization, where the methyl group of the methyl azaarenes represents uniquely reactive input in the Povarov reaction. This method has broad substrate scope and mild conditions. Furthermore, these 2,2'-biquinoline derivatives had been directly used as bidentate ligands in metal-catalyzed reactions.

Visible-light-mediated cascade cyanoalkylsulfonylation/cyclization of alkynoates leading to coumarins via SO2 insertion

A visible-light-mediated cascade cyanoalkylsulfonylation/cyclization of alkynoates with cycloketone oxime compounds for the preparation of 3-cyanoalkylsulfonylcoumarins via SO₂ insertion is reported.

Recent advances and prospects in the metal-free synthesis of quinolines

Metal-free synthesis of quinolines has recently gained attention, and this review focuses on the recent advances in the metal-free synthesis of quinolines.

N-Heterocyclic carbene copper catalyzed quinoline synthesis from 2-aminobenzyl alcohols and ketones using DMSO as an oxidant at room temperature

A facile and practical process for the synthesis of quinolines through an N-heterocyclic carbene copper catalyzed indirect Friedländer reaction from 2-aminobenzyl alcohol and aryl ketones using DMSO as an oxidant at room temperature is reported. A series of quinolines were synthesized in acceptable yields.

A facile and practical process for the synthesis of quinolines through an N-heterocyclic carbene copper catalyzed indirect Friedländer reaction from 2-aminobenzyl alcohol and aryl ketones using DMSO as an oxidant at room temperature is reported.

Visible-light-mediated difunctionalization of vinylcyclopropanes for the synthesis of 1-sulfonylmethyl-3,4-dihydronaphthalenes

An efficient method for the visible-light-mediated sulfonylation/arylation of the C–C σ-bond in vinylcyclopropanes with sulfonyl chlorides to synthesize 1-sulfonylmethyl-substituted 3,4-dihydronaphalenes has been developed.

Biaryl synthesis with arenediazonium salts: cross-coupling, CH-arylation and annulation reactions

The rich legacy of arenediazonium salts in the synthesis of unsymmetrical biaryls, built around the seminal works of Pschorr, Gomberg and Bachmann more than a century ago, continues to make important contributions at various evolutionary stages of modern biaryl synthesis. Based on in-depth mechanistic analysis and design of novel pathways and reaction conditions, the scope of biaryl synthesis with arenediazonium salts has enormously expanded in recent years through applications of transition metal/photoredox-catalysed cross-coupling, thermal/photosensitized radical chain CH-arylation of (hetero)arenes and arylative radical annulation reactions with alkynes. These recent developments have provided facile synthetic access to a wide variety of unsymmetrical biaryls of pharmaceutical, agrochemical and optoelectronic importance with green scale-up options and created opportunities for late-stage modification of peptides, nucleosides, carbon nanotubes and electrodes, the details of which are captured in this review.

Preparation of Ketimines from Aryldiazonium Salts, Arenes, and Nitriles via Intermolecular Arylation of N-Arylnitrilium Ions

A transition-metal-free approach for the preparation of N-arylketimines has been developed from the direct reaction of aryldiazonium salts, arenes, and nitriles in a one-pot fashion with the consecutive formation of N-C and C-C bonds. This approach proceeds via an in situ generation of N-arylnitrilium intermediate, which then undergoes intermolecular arylation. This three-component strategy offers a step- and atom-efficient way to N-arylketimines from easily accessible reagents under mild reaction conditions. The characterization of stereochemistry of ketimine was achieved by X-ray crystallographic structure and theoretical calculation. Operational simplicity, shorter reaction time, excellent functional group compatibility, and scalability are the key features of this report.

Visible-Light-Mediated Ipso-Carboacylation of Alkynes: Synthesis of 3-Acylspiro[4,5]trienones from N-(p-Methoxyaryl)propiolamides and Acyl Chlorides

A novel visible-light-mediated ipso-carboacylation of N-(p-methoxyaryl)propiolamides with acyl chloride has been established for the synthesis of diverse 3-acylspiro[4,5]trienones with high selectivity and efficiency. This method represents a new difunctionalization of alkynes through cross coupling of the acyl chloride C-Cl bonds with an ipso-aromatic carbon by simultaneously forming two new carbon-carbon bonds and one carbon-oxygen double bond.

Visible-light-induced tandem phosphorylation cyclization of vinyl azides under mild conditions

This method provides a visible-light-induced radical tandem cyclization for the synthesis of phosphorus phenanthridines with various nitrogen-containing substrates.

One-pot regioselective synthesis of 2,4-disubstituted quinolines via copper(ii)-catalyzed cascade annulation

A copper(ii)-catalyzed cascade annulation for the one-pot synthesis of 2,4-disubstituted quinolines has been disclosed.

Preparation of 3-Iodoquinolines from N-Tosyl-2-propynylamines with Diaryliodonium Triflate and N-Iodosuccinimide

4-Aryl and 4-alkyl substituted 3-iodoquinolines could be smoothly obtained in one pot by treating N-tosyl-2-propynylamines with diaryliodonium triflate in the presence of K₃PO₄ and a catalytic amount of CuCl at room temperature, followed by treatment with N-iodosuccinimide and BF₃·OEt₂ at 0 °C, and then NaOH in methanol solution. The product, 3-iodo-4-phenylquinoline was smoothly transformed into 4-phenylquinoline with zinc; 4-phenyl-3-toluenesulfenylquinoline with toluenethiol, K₂CO₃, and CuI; 4-phenyl-3-phenylethynylquinoline with the Sonogashira coupling reaction; 4-phenyl-3-styrylquinoline with the Heck coupling reaction; 3,4-diphenylquinoline with the Suzuki-Miyaura coupling reaction; 2-cyclohexyl-3-iodo-4-phenylquinoline with cyclohexanecarboxylic acid, Ag₂CO₃, and K₂S₂O₈; and 3-iodo-2-(2',5'-dioxan-1'-yl)-4-phenylquinoline with benzoyl peroxide in dioxane.

Palladium-catalyzed synthesis of quinolines from allyl alcohols and anilines

A process for quinoline synthesis through palladium-catalyzed oxidative cyclization of aryl allyl alcohols and anilines is described.