Stannous chloride in alcohol: a one-pot conversion of 2-nitro-N-arylbenzamides to 2,3-dihydro-1H-quinazoline-4-ones

Synthesis of Amides via the Amination of Aldehydes with Hydroxylamines Promoted by TBAF·3H2O

A metal-free, mild, and efficient method for the synthesis of amides has been developed from the amination of aldehydes with hydroxylamines promoted by TBAF·3H2O in the presence of KOH. Control experiments showed that the nitrone was the intermediate of this amination. By this method, a series of amides, biologically active compounds bebenil and a COX inhibitor were obtained in moderate to good yields.

Pd(II)-Catalyzed Cascade Annulation of o-Aminobenzoic Acids with CO, Amines, and Aldehydes to N3-/N1,N3-Substituted 2,3-Dihydroquinazolin-4(1H)-ones

The unprecedented Pd(II)-catalyzed cascade annulation of o-aminobenzoic acids with CO, amines, and aldehydes has been developed. This protocol provides an efficient and concise approach to selective construction of N3-substituted and N1,N3-disubstituted 2,3-dihydroquinazolin-4(1H)-ones mostly in moderate to excellent yields from simple and easily available starting materials under mild conditions featured with low cost, high step economy, broad substrate scope, and good product diversity.

2,3-Dihydro-Quinazolin-4(1H)-One as a Fluorescent Sensor for Hg2+ Ion and its Docking Studies in Cancer Treatment

The 2,3-dihydro-quinazolin-4(1H)-one was synthesised via the deployment of SBA-Pr-SO3H and its application was explored as a highly selective fluorescent sensor for Hg2+ ion; fluorescence intensity was decreased selectively by Hg2+ ions. Furthermore, this compound also indicated for its superb anti-interference ability among other ions. It is important to mention that this compound could be employed to detect a very low amount of Hg2+ ions, which are highly toxic and general contaminants. The docking study shows that the molecule, 2,3-dihydro-quinazolin-4(1H)-one, is a good inhibitor for the 5ACC enzyme.

Gold(I)-Catalyzed Tandem Synthesis of Polycyclic Dihydroquinazolinones

A gold-catalyzed cascade process for the synthesis of dihydroquinazolinone scaffolds was developed. A series of gold catalysts were screened for this tandem transformation, and the (PPh3)AuCl/AgOTf catalyst combination was found to be the best catalyst system. This method is characterized by good yields, high regioselectivity, and broad substrate scope. This method is also applicable to the synthesis of tetracyclic dihydroquinazolinones and seven-membered ring-fused dihydroquinazolinones.

Transition-Metal-Free Transfer Hydrogenative Cascade Reaction of Nitroarenes with Amines/Alcohols: Redox-Economical Access to Benzimidazoles

This report describes an efficient transition-metal-free process toward the transfer hydrogenative cascade reaction between nitroarenes and amines or alcohols. The developed redox-economical approach was realized using a combination of KO^tBu and Et₃SiH as reagents, which allows the synthesis of benzimidazole derivatives via σ-bond metathesis. The reaction conditions hold well over a wide range of substrates embedded with diverse functional groups to deliver the desired products in good to excellent yields. The mechanistic proposal has been depicted on the basis of a series of control experiments, mass spectroscopic evidence which is well supported by density functional theory (DFT) calculations with a feasible energy profile.

β-Cyclodextrin: a supramolecular catalyst for metal-free approach towards the synthesis of 2-amino-4,6-diphenylnicotinonitriles and 2,3-dihydroquinazolin-4(1H)-one

β-Cyclodextrin, a green and widespread supramolecular catalyst, has been explored as a highly proficient promoter for the metal-free one-pot multi-component synthesis of a vast range of highly functionalized bioactive heterocyclic moiety, 2-amino-4,6-diphenylnicotinonitriles and 2,3-dihydroquinazolin-4(1H)-one, from easily available precursor aldehydes. The main endeavor of these protocols is to explore this organic supramolecule in one-pot multi-component synthesis. Absence of metal catalyst or toxic acid and harsh reaction conditions, excellent functional group tolerance, inexpensive, greener and environmentally safe protocol are the key advantages of this work.

Highly productive and scalable approach to synthesize ticlopidine: A potent thienopyridine anti-platelet aggregation drug

Ticlopidine (trade name Ticlid), an acidic thienopyridine derivative, is an effective, well-known and long-acting inhibitor of platelet aggregation. Because of its potent inhibitory activity for treating a variety of diseases, the development of efficient approaches for accessing ticlopidine represents an important endeavour. Therefore, in this research work, we developed a promising novel five-step synthetic approach for synthesizing ticlopidine. This method provides ticlopidine in 60% overall yield from readily available starting material viz. thiophene. In this methodology, all steps afforded excellent yields and are operationally simple and environmentally acceptable. This approach also offers various attractive advantages, for example, it's applicable for large-scale synthesis, has simple work-up procedures and short reaction times, and uses inexpensive and readily available reagents. Furthermore, 4,5,6,7-tetrahydrothieno[3,2-c]pyridine is a key precursor for the synthesis of numerous bioactive compounds such as prasugrel and clopidogrel. This protocol provides 4,5,6,7-tetrahydrothieno[3,2-c]pyridine in 62% overall yield via a 4-step synthetic approach.

A Simple, Efficient, and Eco-Friendly Method for the Preparation of 3-Substituted-2,3-dihydroquinazolin-4(1H)-one Derivatives

A simple, cost-effective method under environmentally benign conditions is a very important concept for the preparation of 2,3-dihydroquinazolin-4(1H)-one derivatives. The present work describes an efficient and eco-friendly protocol for the synthesis of 2-amino-N-(2-substituted-ethyl)benzamide and 3-substituted-2,3-dihydroquinazolin-4(1H)-one derivatives. The novel feature of this protocol is the use of 2-methyl tetrahydrofuran (2-MeTHF) as an eco-friendly alternative solvent to tetrahydrofuran (THF) in the first step. In the second step, methanol in the presence of potassium carbonate as a catalyst was used under conventional heating or microwave irradiation, which provided an eco-friendly method to afford the target products in excellent yields and purities. NMR (1H and 13C), elemental analysis, and LC-MS confirmed the structures of all compounds. X-ray crystallography further confirmed the structure of the intermediate 2-amino-N-(2-substituted-ethyl)benzamide 3a. The molecular structure of 3a was monoclinic crystal, with P21/c, a = 13.6879 (11) Å, b = 10.2118 (9) Å, c = 9.7884 (9) Å, β = 105.068 (7)°, V = 1321.2 (2) Å3, and Z = 4.

Design and Molecular Docking Studies of Some 2,3 Di-Substituted Quinazolin-4-One Analogues Against Staphylococcus aureus UDG

BACKGROUND

In this present investigation, some 2, 3 disubstituted-quinazolin-4-one derivatives are designed and docked against chain A and chain B of (3WDF) receptor.

METHODS

The heterocyclic fused rings quinazolinone have drawn a great attention owing to their expanded applications in the field of pharmaceutical chemistry. The diverse range of molecules with quinazoline/quinazolinone moieties have been reported to exhibit a broad spectrum of biological activities.

RESULTS

The results designate that the quinazolinone ring forms hydrophobic and hydrogen bond contacts with ASN 127 A, ALA 126 A, and SER 83 B, SER 183 B amino acid residue.

CONCLUSION

Molecular docking is safe and straightforward to use tool which facilitates in investigating, interpreting, enplaning and identification of molecular properties using 3D structures.

Microwave-assisted synthesis of quinazolin-4(3H)-ones catalyzed by SbCl3

Antimony(III) trichloride (SbCl3) is an effective catalyst (1 mol%) for the condensation of anthranilic amide with various aldehydes or ketones to quinazolin-4(3H)-one derivatives in good to excellent yields under microwave irradiation. The process is carried out within several minutes under solvent-free conditions. This general methodology has the advantages of simplicity, mild reaction conditions and high yields of products.

2,3-Dihydroquinazolin-4(1H)-one as a privileged scaffold in drug design

2,3-Dihydroquinazolin-4-one (DHQ) belongs to the class of nitrogen-containing heterocyclic compounds representing a core structural component in various biologically active compounds. In the past decades, several methodologies have been developed for the synthesis of the DHQ framework, especially the 2-substituted derivatives. Unfortunately, multistep syntheses, harsh reaction conditions, and the use of toxic reagents and solvents have limited their full potential as a versatile fragment. Recently, use of green chemistry and alternative strategies are being explored to prepare diverse DHQ derivatives. This fragment is used as a synthon for the preparation of biologically active quinazolinones and as a functional substrate for the synthesis of modified DHQ derivatives exhibiting different biological properties. In this review, we provide a comprehensive assessment of the synthesis and biological evaluations of DHQ derivatives.

Oxone-mediated annulation of 2-aminobenzamides and 1,2-diaminobenzenes withsec-aminesviaimine-N-oxides: new syntheses of 2,3-dihydroquinazolin-4(1H)-ones and 1H-benzimidazoles

Synthesis of 2,3-dihydroquinazolin-4(1H)-ones and 1H-benzimidazoles by reaction of imine-N-oxides with 2-aminobenzamides and 1,2-diaminobenzenes is described.

Organic–inorganic hybrid polyoxometalate and its graphene oxide–Fe3O4nanocomposite, synthesis, characterization and their applications as nanocatalysts for the Knoevenagel condensation and the synthesis of 2,3-dihydroquinazolin-4(1H)-ones

Organic–inorganic hybrid of H₆Cu₂[PDA]₆[SiW₉Cu₃O₃₇]·12H₂O (HybPOM), was synthesized and grafted on graphene oxide decorated with Fe₃O₄. The structures of HybPOM and GO@Fe₃O₄@HybPOM nanocomposites were characterized and their catalytic activities investigated.

Hydroxyapatite nanoparticles (HAP NPs): a green and efficient heterogeneous catalyst for three-component one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives in aqueous media

HAP NPs were applied as a green heterogeneous catalyst for synthesis of 2,3-dihydroquinazolin-4(1H)-one derivatives. The nanocatalyst was prepared and characterized.

Copper-catalyzed radical methylation/C-H amination/oxidation cascade for the synthesis of quinazolinones

A copper-catalyzed radical methylation/sp(3) C-H amination/oxidation reaction for the facile synthesis of quinazolinone was developed. In this cascade reaction, dicumyl peroxide acts not only as a useful oxidant but also as an efficient methyl source. Notably, a methyl radical, generated from peroxide, was confirmed by electron paramagnetic resonance for the first time.

A catalyst-free rapid, practical and general synthesis of 2-substituted quinazolin-4(3H)-ones leading to luotonin B and E, bouchardatine and 8-norrutaecarpine

Formamide has been identified as an ammonia surrogate in the construction of quinazolin-4(3H)-one ring leading to several alkaloids.

An ionic liquid catalyzed reusable protocol for one-pot synthesis of 2,3-dihydroquinazolin-4(1H)-one under mild conditions

This article describes an efficient protocol for the syntheses of 2,3-dihydroquinazolinones. The synthetic utility of this methodology has been demonstrated with 30 different substrates. The reaction showed good functional group tolerance and high levels of catalytic activity.