One-Pot Copper(I)-Catalyzed Ligand/Base-Free Tandem Cyclooxidative Synthesis of Quinazolinones

Selective Oxidative Methyl C-H Functionalization of Butylated Hydroxytoluene toward Arylimines/N-Heterocycles

A metal-free and selective oxidative methyl C-H functionalization of BHT with aniline compounds has been developed. This innovative method enables the facile and efficient synthesis of a diverse array of BHT-functionalized N-containing skeletons, including arylamines, benzoxazoles, benzothiazoles, benzimidazoles, quinazolines, and quinazolinones, all of which are challenging to access. The control experiment involving TEMP18O suggests that the radical adduct of TEMPO with the benzyl radical of BHT may serve as an intermediate.

Microwave-assisted commercial copper-catalyzed aerobic oxidative synthesis of AChE quinazolinone inhibitors under solvent free conditions

A facile and green one-pot synthesis of AChE quinazolinone inhibitors was developed using microwave irradiation under solvent free conditions. Quinazolinones were synthesized from 2-aminobenzamide derivatives and various alcohols such as benzyl alcohol derivatives and butanol using economical commercially available copper as a catalyst in the presence of base, Cs2CO3. The desired products were achieved in moderate to high yields with up to 92% isolated yield. These quinazolinone products were then evaluated for acetylcholinesterase inhibition so that they can be developed as promising anti-acetylcholinesterase agents.

Cobalt Homeostatic Catalysis for Coupling of Enaminones and Oxadiazolones to Quinazolinones

Transition metal catalysis has revolutionized modern synthetic chemistry for its diverse modes of coordination reactivity. However, this versatility in reactivity is also the predominant cause of catalyst deactivation, a persisting issue that can significantly compromise its synthetic value. Homeostatic catalysis, a catalytic process that can sustain its productive catalytic cycle even when chemically disturbed, is proposed herein as an effective tactic to address the challenge. In particular, a cobalt homeostatic catalysis process has been developed for the water-tolerant coupling of enaminones and oxadiazolones to quinazolinones. Dynamic covalent bonding serves as a mechanistic handle for the preferred buffering of water onto enaminone and reverse exchange by a released secondary amine, thus securing reversible entry into cobalt's dormant and active states for productive catalysis. Through this homeostatic catalysis mode, a broad structural scope has been achieved for quinazolinones, enabling further elaboration into distinct pharmaceutically active agents.

Tandem Reduction, Ammonolysis, Condensation, and Deamination Reaction for Synthesis of Benzothiadiazines and 1-(Phenylsulfonyl)-1H-benzimidazoles

A novel route for a SnCl₂-promoted tandem reduction, ammonolysis, condensation, and deamination reaction which uses nitrile and 2-nitro-N-phenylbenzenesulfonamide/N-(2-nitrophenyl)benzenesulfonamide to synthesize derivatives of benzothiadiazine/1-(phenylsulfonyl)-1H-benzimidazole has been developed. The method features convenient operation and good functional group tolerance. In addition, it employs unsensitive and inexpensive SnCl₂/i-PrOH as the reaction reagent and provides a direct approach for the synthesis of pharmaceutically important targets.

Ru Doped Hydrotalcite Catalyzed Borrowing Hydrogen-Mediated N-Alkylation of Benzamides, Sulfonamides, and Dehydrogenative Synthesis of Quinazolinones

An efficient Ru doped hydrotalcite catalyzed N-alkylation of benzamides and sulfonamides with alcohols via borrowing hydrogen catalysis is illustrated. Various primary alcohols, including benzyl, heteroaryl, and aliphatic alcohols, were alkylated in good to excellent yields. To shed light on the mechanistic details, several control studies and deuterium labeling experiments were performed. Mechanistic studies underpin that the reaction is going via a borrowing hydrogen pathway rather than an S_N1 type mechanism. The reaction can be easily scaled up without any detrimental effect on the yield. The catalyst is also capable of synthesizing quinazolinone directly from 2-aminobenzamide and alcohols. Successful recyclability and high reactivity highlight the practical applicability of the catalyst.

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...

Regioselective Synthesis of 2° Amides Using Visible-Light-Induced Photoredox-Catalyzed Nonaqueous Oxidative C-N Cleavage of N,N-Dibenzylanilines

A visible-light-driven photoredox-catalyzed nonaqueous oxidative C-N cleavage of N,N-dibenzylanilines to 2° amides is reported. Further, we have applied this protocol on 2-(dibenzylamino)benzamide to afford quinazolinones with (NH₄)₂S₂O₈ as an additive. Mechanistic studies imply that the reaction might undergo in situ generation of α-amino radical to imine by C-N bond cleavage followed by the addition of superoxide ion to form amides.

Selective Synthesis of 2-(1,2,3-Triazoyl) Quinazolinones through Copper-Catalyzed Multicomponent Reaction

We describe here our results from the copper-catalyzed three component reaction of 2-azidobenzaldehyde, anthranilamide and terminal alkynes, using Et3N as base, and DMSO as solvent. Depending on the temperature and amount of Et3N used in the reactions, 1,2,3-triazolyl-quinazolinones or 1,2,3-triazolyl-dihydroquinazolinone could be obtained. When the reactions were performed at 100 °C using 2 equivalents of Et3N, 1,2,3-triazolyl-dihydroquinazolinone was formed in 82% yield, whereas reactions carried out at 120 °C using 1 equivalent of Et3N provided 1,2,3-triazolyl-quinazolinones in moderate-to-good yields.

Unexpected Insertion of Nitrogen into a C-C Bond: Access to 2,3-Disubstituted Quinazolinone Scaffolds

A novel, practical, highly efficient, and transition metal free nitrogen insertion reaction for the synthesis of 2,3-disubstituted quinazolinone derivatives was developed. Diverse functionalized 3-indolinone-2-carboxylates and nitrosoarenes with a wide range of substituted nitrosobenzenes, nitrosopyridines, dibenzofuranyl, or dibenzothienyl nitroso compounds worked smoothly to give 2,3-disubstituted quinazolinone derivatives in good to excellent yields (69-98%). A gram-scale reaction was achieved, and an afloqualone analogue was synthesized under the mild reaction conditions.

A magnetically retrievable copper ionic liquid nanocatalyst for cyclooxidative synthesis of 2-phenylquinazolin-4(3H)-ones

In the present work, we report the design and fabrication of a copper-containing ionic liquid supported magnetic nanocatalyst via a convenient and straightforward synthetic approach for the formation of 2-phenylquinazolin-4(3H)-ones using o-aminobenzamide and benzaldehydes as the reaction partners. The successful formation and properties of the as-prepared catalyst have been thoroughly investigated using diverse physico-chemical techniques including FT-IR, XRD, FE-SEM, TEM, ICP, VSM, BET and TGA. Using this nanocatalytic system, a variety of 2-phenylquinazolin-4(3H)-ones are synthesized in excellent yields with operational ease and short reaction times in an environmentally preferable solvent under open air and without using any external oxidizing agent. Besides, the catalyst possessed facile magnetic recoverability and remarkable reusability for six consecutive runs without any appreciable decrease in the catalytic efficiency.

Electrochemically induced synthesis of quinazolinones via cathode hydration of o-aminobenzonitriles in aqueous solutions

An efficient and practical electrochemically catalyzed transition metal-free process for the synthesis of substituted quinazolinones from simple and readily available o-aminobenzonitriles and aldehydes in water has been accomplished. I₂/base and water play an unprecedented and vital role in the reaction. By electrochemically catalysed hydrolysis of o-aminobenzonitriles, the synthesis of quinazolinones with benzaldehyde was first proposed. The synthetic utility of this method was demonstrated by gram-scale operation, as well as the preparation of bioactive N-(2,5-dichlorophenyl)-6-(2,2,2-trifluoroethoxy) pteridin-4-amine, which enables straightforward, practical and environmentally benign quinazolinone formation.

Metal-free synthesis of 1,4-benzodiazepines and quinazolinones from hexafluoroisopropyl 2-aminobenzoates at room temperature

Herein, we describe the novel reactivity of hexafluoroisopropyl 2-aminobenzoates. The metal-free synthesis of 1,4-benzodiazepines and quinazolinones from hexafluoroisopropyl 2-aminobenzoates has been developed at room temperature. These procedures feature good functional group tolerance, mild reaction conditions, and excellent yields. The newly formed products can readily be converted to other useful N-heterocycles. Moreover, the products and their derivatives showed potent anticancer activities in vitro by MTT assay.

A metal-free synthesis of 1,4-benzodiazepines and quinazolinones from hexafluoroisopropyl 2-aminobenzoates has been developed at room temperature.

Cobalt-Catalyzed Tandem Transformation of 2-Aminobenzonitriles to Quinazolinones Using Hydration and Dehydrogenative Coupling Strategy

A tandem synthesis of quinazolinones from 2-aminobenzonitriles is demonstrated here by using an aliphatic alcohol-water system. For this transformation, a cheap and easily available cobalt salt and P(CH₂CH₂PPh₂)₃ (PP₃) ligand were employed. The substrate scope, scalability, and synthesis of natural products exhibited the vitality of this protocol.

Base-promoted Lewis acid catalyzed synthesis of quinazoline derivatives

A one-pot protocol has been developed for the synthesis of quinazolinones from amide-oxazolines with TsCl via a cyclic 1,3-azaoxonium intermediate and 6π electron cyclization in the presence of a Lewis acid and base. The process is operationally simple and has a broad substrate scope. This method provides a unique strategy for the construction of quinazolinones.

Synthesis of quinazoin-4-ones through an acid ion exchange resin mediated cascade reaction

An interesting cascade reaction of N-(2-(4,5-dihydrooxazol-2-yl)phenyl)benzamide in the presence of an acid ion exchange resin is described. In this reaction, a range of substrates bearing various substituent groups are well compatible. This work provides a green and atom-economical alternative approach for the synthesis of quinazolin-4-ones in good yields.

ortho-Naphthoquinone-catalyzed aerobic oxidation of amines to fused pyrimidin-4(3H)-ones: a convergent synthetic route to bouchardatine and sildenafil

A facile access to fused pyrimidin-4(3H)-one derivatives has been established by using the metal-free ortho-naphthoquinone-catalyzed aerobic cross-coupling reactions of amines. The utilization of two readily available amines allowed a direct coupling strategy to quinazolinone natural product, bouchardatine, as well as sildenafil (Viagra™) in a highly convergent manner.

Fused pyrimidin-4(3H)-one derivatives have been accessed by using the ortho-naphthoquinone-catalyzed aerobic cross-coupling reactions of amines.

Aerobic oxidative synthesis of quinazolinones and benzothiazoles in the presence of laccase/DDQ as a bioinspired cooperative catalytic system under mild conditions

The current study applied laccase/DDQ as a bioinspired cooperative catalytic system for the synthesis of quinazolinones (80–95% yield) and benzothiazoles (65–98% yield) using air or O₂ as ideal oxidants in aqueous media at ambient temperature. The aerobic oxidative cyclization reactions occur in two steps: (i) chemical cyclization; (ii) chemoenzymatic oxidation. These methods are more environment-friendly, efficient, simple and practical than other reported methods due to the use of O₂ as an oxidant, laccase as an eco-friendly biocatalyst, aqueous media as the solvent and free from any toxic transition metal and halide catalysts. Therefore, these methods can be applied in pharmaceutical and other sensitive synthetic procedures.

In this paper laccase/DDQ as a bioinspired cooperative catalytic system was applied for the synthesis of quinazolinones and benzothiazoles using air or O₂ as ideal oxidant in aqueous media under mild conditions.

Effect of Fe(iii)-based MOFs on the catalytic efficiency of the tandem cyclooxidative reaction between 2-aminobenzamide and alcohols

Fe-MOFs were used as efficient heterogeneous catalysts in the tandem cyclooxidative reaction under microwave irradiation.

Efficient Synthesis of Quinazolinones by Transition-Metal-Free Direct Aerobic Oxidative Cascade Annulation of Alcohols with o-Aminoarylnitriles

A mild and atom-economic method was developed for direct and efficient synthesis of quinazolinones through a transition-metal-free aerobic oxidative cascade annulation reaction of widely available o-aminoarylnitriles and alcohols. Air could be employed as an effective oxidant under mild conditions, generating water as the only byproduct. Possibly owing to the "cesium effect", the water-soluble base CsOH was found to be crucial in all key steps of the reaction mechanism. Because a wide range of substrates can be used to prepare substituted quinazolinones without contamination by transition-metal residues, this method may be of interest for application in pharmaceutical synthesis. Possible reaction paths were also proposed according to control reactions.

Quinazolinone Synthesis through Base-Promoted SNAr Reaction of ortho-Fluorobenzamides with Amides Followed by Cyclization

A transition-metal-free synthesis of quinazolin-4-ones by Cs₂CO₃-promoted S_NAr reaction of ortho-fluorobenzamides with amides followed by cyclization in dimethyl sulfoxide has been developed. The present procedure can provide efficient synthetic methods for the formation of both 2-substituted and 2,3-disubstituted quinazolin-4-one rings depending on the use of easily available starting materials and an efficient, one-pot protocol for the synthesis of the marketed drug product of methaqualone.

Transition metal-free synthesis of quinazolinones using dimethyl sulfoxide as a synthon

Biologically important quinazolinones have been synthesized from 2-aminobenzamides and DMSO.

"On-Water" Synthesis of Quinazolinones and Dihydroquinazolinones Starting from o-Bromobenzonitrile

A versatile and practical “on-water” protocol was newly developed to synthesize quinazolinones using o-bromobenzonitrile as a novel starting material. Studies have found that air as well as water plays an important role in synthesis of quinazolinones. Further investigation indicated that dihydroquinazolinones can be prepared with this protocol under the protection of N₂. The protocol can be extended to other substrates and various quinazolinones and dihydroquinazolinones were obtained. o-Bromobenzamide, o-aminobenzonitrile, and o-aminobenzamide were also evaluated as starting materials, and the results further proved the versatility of this protocol, especially towards dihydroquinazolinones.