Copper-Catalyzed Multicomponent Domino Reaction of 2-Bromoaldehydes, Benzylamines, and Sodium Azide for the Assembly of Quinazoline Derivatives

Recent Advances in Metal-Catalyzed Approaches for the Synthesis of Quinazoline Derivatives

Quinazolines are an important class of heterocyclic compounds that have proven their significance, especially in the field of organic synthesis and medicinal chemistry because of their wide range of biological and pharmacological properties. Thus, numerous synthetic methods have been developed for the synthesis of quinazolines and their derivatives. This review article briefly outlines the new synthetic methods for compounds containing the quinazoline scaffold employing transition metal-catalyzed reactions.

A TEMPO promoted tandem reaction of 2-aminobenzophenones and benzylamines under electrochemical conditions

This study describes the efficient synthesis of quinazolines promoted by TEMPO via electro-catalysis with 2-aminobenzophenones and benzylamines. The method exhibited remarkable chemoselectivity under mild reaction conditions. A series of quinazolines could be obtained in moderate to good yields. In addition, control experiments were carried out to verify the reaction mechanism. Furthermore, the synthesis on the gram scale was conducted successfully to give the target product.

Transition-metal-catalyzed synthesis of quinazolines: A review

Quinazolines are a class of nitrogen-containing heterocyclic compounds with broad-spectrum of pharmacological activities. Transition-metal-catalyzed reactions have emerged as reliable and indispensable tools for the synthesis of pharmaceuticals. These reactions provide new entries into pharmaceutical ingredients of continuously increasing complexity, and catalysis with these metals has streamlined the synthesis of several marketed drugs. The last few decades have witnessed a tremendous outburst of transition-metal-catalyzed reactions for the construction of quinazoline scaffolds. In this review, the progress achieved in the synthesis of quinazolines under transition metal-catalyzed conditions are summarized and reports from 2010 to date are covered. This is presented along with the mechanistic insights of each representative methodology. The advantages, limitations, and future perspectives of synthesis of quinazolines through such reactions are also discussed.

Late-stage diversification of indole skeletons through nitrogen atom insertion

Compared with peripheral late-stage transformations mainly focusing on carbon-hydrogen functionalizations, reliable strategies to directly edit the core skeleton of pharmaceutical lead compounds still remain scarce despite the recent flurry of activity in this area. Herein, we report the skeletal editing of indoles through nitrogen atom insertion, accessing the corresponding quinazoline or quinoxaline bioisosteres by trapping of an electrophilic nitrene species generated from ammonium carbamate and hypervalent iodine. This reactivity relies on the strategic use of a silyl group as a labile protecting group that can facilitate subsequent product release. The utility of this highly functional group-compatible methodology in the context of late-stage skeletal editing of several commercial drugs is demonstrated.

Cucurbit[6]uril supported β-Ni(OH)2 nanoparticles as a heterogeneous catalyst for the synthesis of quinazolines via acceptorless dehydrogenative coupling of alcohols with nitriles

Synthesis of a series of quinazolines using β-Ni(OH)2-CB[6] as a heterogeneous nanocatalyst.

Recent Advances in the Tandem Copper-Catalyzed Ullmann-Goldberg N-Arylation–Cyclization Strategies

N‒Aryl bond formation under copper catalysis has been playing a pivotal role and has been extensively used as a key step in the total syntheses of several therapeutic molecules. The...

Palladium(ii) N,N,O-pincer type complex-mediated dehydrogenative coupling of alcohols to quinazolines

A diverse range of quinazolines were synthesized in moderate to high yields using 0.5 mol% Pd(ii) catalyst loading under aerobic conditions.

Rapid Construction of Substituted Dihydrothiophene Ureidoformamides at Room Temperature Using Diisopropyl Ethyl Ammonium Acetate: A Green Perspective

An economic, sustainable, and straightforward environmentally friendly synthesis of highly diversified polyfunctional dihydrothiophenes is successfully achieved via diisopropyl ethyl ammonium acetate as a room-temperature ionic liquid. Multicomponent synthesis contains domino processes; the benefit of this present protocol is highlighted by its readily available starting materials, superior functional group tolerance, purity of synthesized compounds was checked by high-performance liquid chromatography results in up to 99.7% purity for the synthesized compounds, reaction mass efficiency, effective mass yield, and excellent atom economy. In addition, a series of 2-(N-carbamoyl acetamide)-substituted 2,3-dihydrothiophene analogs were synthesized, and selected samples were chosen for testing their in vitro antibacterial and antifungal activities. Furthermore, a molecular docking study against sterol 14α-demethylase could provide valuable insight into the mechanism of antifungal action providing an opportunity for structure-based lead optimization.

Dirhodium(II)-Catalyzed C(sp2 )-H Azidation of Benzaldehydes

Multiple steps are needed to achieve the C-H functional of aromatic aldehyde, since the C-H functional reaction usually occurs preferentially at the aldehydic C-H bond over the aryl C-H bond. We report an efficient azidation method mediated by dirhodium(II) catalysts to achieve the direct aryl azidation of aromatic aldehydes avoiding the simultaneous use of protected aldehydes and prefunctionalized arenes. The regioselectivity of this method is similar to those of typical aromatic electrophilic substitution reactions. The resulting azidobenzaldehyde products are versatile building blocks or precursors for the synthesis of many biologically active compounds. The mechanism studies indicate that the one-electron oxidative intermediate Rh₂ ^(II,III) N₃ is responsible for the azide transfer.

Copper-Catalyzed Multicomponent Domino Reaction of 2-Bromobenzaldehydes, Aryl Methyl Ketones, and Sodium Azide: Access to 1 H-[1,2,3]Triazolo[4,5- c]quinoline Derivatives

A practical copper-catalyzed multicomponent reaction has been developed for the synthesis of 1 H-[1,2,3]triazolo[4,5- c]quinoline derivatives from commercially available 2-bromobenzaldehydes, aryl methyl ketones, and sodium azide. This protocol integrated consecutive base-promoted condensation, [3 + 2] cycloaddition, copper-catalyzed S_NAr, and denitrogenation cyclization sequences. Preliminary mechanistic studies revealed that CuBr₂ acted as a multifunctional catalyst to streamline this domino process. The mild catalytic system enabled effective construction of one C-C and four C-N bonds in one operation.

Base-Promoted Synthesis of 2-Aryl Quinazolines from 2-Aminobenzylamines in Water

A transition-metal-free procedure for the synthesis of a highly valuable class of heteroaromatics, quinazolines, was developed by using easily available 2-aminobenzylamines and α,α,α-trihalotoluenes. The transformation proceeded smoothly in the presence of only sodium hydroxide and molecular oxygen in water at 100 °C, furnishing a variety of 2-aryl quinazolines. The crystallization process of the crude reaction mixture for the purification of the solid products circumvents huge solvent-consuming workup and column chromatographic techniques, which make the overall process more sustainable and economical.

Synthesis of Pyrimidine Fused Quinolines by Ligand-Free Copper-Catalyzed Domino Reactions

Herein, we report two novel methods for the synthesis of pyrimidine fused quinolines using a one-pot C-C and C-N bond forming strategy from the reaction of 6-aminouracils with 2-bromobenzaldehydes or 2-bromobenzyl bromide derivatives in the presence of 10 mol % CuCl₂ without using any ligand. The reaction of 2-bromobenzaldehyde or its derivatives with 6-aminouracils in the presence of K₂CO₃ as base and a catalytic amount of CuCl₂ in DMF medium under microwave heating conditions provides corresponding pyrimidine fused quinoline derivatives in good yields within 30 min. Alternatively, pyrimidine fused quinoline derivatives have been synthesized from the reaction of 2-bromobenzyl bromides with 6-aminouracil derivatives in the presence of molecular oxygen, CuCl₂ (10 mol %), and K₂CO₃ as base in DMF under reflux conditions. Structures of all the products were unambiguously confirmed by spectroscopic techniques and by recording single crystal XRD of 3a.

Ring-opening and cyclization of aziridines with aryl azides: metal-free synthesis of 6-(triflyloxy)quinolines

A metal-free synthesis of 6-(triflyloxy)quinolines has been developed via the ring-opening and cyclization of 2-aryl-1-tosylaziridines with 2-azidobenzaldehydes in the presence of TfOH.

Pd-Catalyzed tandem reaction of N-(2-cyanoaryl)benzamides with arylboronic acids: synthesis of quinazolines

A Pd-catalyzed tandem reaction of N-(2-cyanoaryl)benzamides with arylboronic acids for the synthesis of quinazolines has been reported.

tert-Butyl nitrite (TBN) as the N atom source for the synthesis of substituted cinnolines with 2-vinylanilines and a relevant mechanism was studied

A green method to synthesize cinnolines by 6π electrocyclic reaction with alkenyl amines and TBN has been developed.

AgNO2 as the NO Source for the Synthesis of Substituted Pyrazole N-Oxides from N-Propargylamines

A straightforward method for synthesizing the pyrazole N-oxides from N-propargylamines and AgNO₂ through oxidation/cyclization reaction had been developed. AgNO₂ was used as the NO source for the first time to synthesize pyrazole N-oxides. Various substituted groups on N-propargylamines proceeded smoothly, and the desired products were obtained in good yields.

AgNO3 as nitrogen source for rhodium(iii)-catalyzed synthesis of 2-aryl-2H-benzotriazoles from azobenzenes

A new approach has been established for Rh(iii)-catalyzed direct aza oxidative cyclization of non-prefunctionalized azobenzenes to provide 2-aryl-2H-benzotriazoles in good yields.

A copper catalyzed multicomponent cascade redox reaction for the synthesis of quinazolinones

A copper catalyzed multicomponent cascade redox reaction for the synthesis of various quinazolinones starting from easily available 2-bromobenzamides, benzylic alcohols and sodium azide as a nitrogen source has been developed.