Synthesis of Quinazoline and Quinazolinone Derivatives via Ligand-Promoted Ruthenium-Catalyzed Dehydrogenative and Deaminative Coupling Reaction of 2-Aminophenyl Ketones and 2-Aminobenzamides with Amines

Cu(II)-Doped ZIF-8 as a Sustainable Catalyst for the Dehydrogenative Coupling of 2-Aminobenzamide with Methanol

In this study, an effective and stable Cu2+ incorporated within the lattice of ZIF-8 was hydrothermally synthesized and employed as a heterogeneous catalyst for the dehydrogenative coupling between 2-aminobenzamide and CH3OH. The Cu2+-doped ZIF-8 (Cu@ZIF-8) catalysts were firmly characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflectance spectra, and Brunauer-Emmett-Teller techniques to examine their structural, morphological, elemental, optical, and surface properties. The catalytic efficiency of Cu@ZIF-8 was investigated in the synthesis of quinazolinone from 2-aminobenzamide and CH3OH as a C1 source with Cs2CO3 as a base under an oxygen atmosphere. Among the different catalysts, 30% Cu@ZIF-8 catalyst demonstrated superior activity in the formation of quinazolinone compared to pristine ZIF-8, indicating that the doping of the Cu2+ ions provides a synergetic effect during the reaction. Furthermore, reusability experiments were carried out with a 30% Cu@ZIF-8 catalyst, and the observed findings show that the activity is maintained up to four cycles. The structural integrity along with the morphology and chemical structure of the reused solid were also verified, and no significant differences between the fresh and reused solids were observed in the dehydrogenative coupling reaction. Furthermore, a plausible reaction mechanism for this reaction is also proposed.

Catalyst-free and oxidant-free cyclocondensation of 2-aminobenzamides with glycosides under visible light

A convenient and practical method for the mild synthesis of quinazolinones has been developed under visible light at room temperature in the absence of catalysts or additional oxidants. Under very mild reaction conditions, the quinazolinone moiety can be successfully introduced into deoxyuridine and helicid. This method afforded various 5-substituted deoxyuridine analogs and 4-substituted helicid derivatives in moderate to good yields (without column chromatography) across diverse aromatic and aliphatic aldehydes, proving effective for late-stage drug functionalization.

TBAI-mediated electrochemical oxidative synthesis of quinazolin-4(3H)-ones from 2-aminobenzamides and isothiocyanates

A practical protocol has been established to access 2-aminoquinazolin-4(3H)-one derivatives through the electrochemical desulfurative cyclization of 2-aminobenzamides and isothiocyanates. The protocol allows for the formation of C-N bonds under mild conditions without metal catalysts or external oxidants. The practicability of this strategy is demonstrated by its broad substrate scope, good functional group compatibility, and scale-up synthesis.

Symmetrical Bis-Hydrazone Ligand-Based Binuclear Oxido/Dioxido-Vanadium(IV/V) Complexes: Synthesis, Reactivity, and Catalytic Applications for the Synthesis of Biologically Potent 2-Phenylquinazolin-4-(3H)-ones

Symmetrical bis(hydrazone)-based ligands, H4dar(bhz)2 (I), H4dar(fah)2 (II), H4dar(nah)2 (III), and H4dar(inh)2 (IV) obtained from 4,6-diacetylresorcinol (H2dar) and different hydrazides [benzoylhydrazide (Hbhz), isonicotinoylhydrazide (Hinh), nicotinoylhydrazide (Hnah), and 2-furoylhydrazide (Hfah)], were used to prepare potassium salts of binuclear cis-[VVO2]+ complexes, {K(H2O)2}2[(VVO2)2dar(bhz)2] (1), {K(H2O)2}2[(VVO2)2dar(fah)2] (2), {K(H2O)2}2[(VVO2)2dar(nah)2] (3), and {K(H2O)2}2[(VVO2)2dar(inh)2] (4), and binuclear [VIVO]2+ complexes, [{VIVO(MeOH)}2dar(bhz)2] (5), [{VIVO(MeOH)}2dar(fah)2] (6), [{VIVO(MeOH)}2dar(nah)2] (7), and [{VIVO(MeOH)}2dar(inh)2] (8). In the presence of warm MeOH/DMSO (4:1), 3 changed to {K(H2O)2}[(VVO2)2Hdar(nah)2]·DMSO (3a·DMSO). Single crystal XRD studies of 1 and 3a confirm a binuclear structure along with a distorted square pyramidal geometry of each vanadium center where bis{ONO(2-)} ligands coordinate through phenolate-O, azomethine-N, and enolate-O atoms of each unit. While growing crystals of 6 in EtOH, part of it oxidizes and gives [{VVO(OEt)}2dar(fah)2] (9) along with powdery 6. Complex 9 has a distorted octahedral structure. These complexes were used as catalysts for the synthesis of biologically important 2-phenylquinazolin-4-(3H)-ones having different aryl aldehydes, and they all show excellent catalytic performance (up to 97% yield) in less reaction time and low temperature, in the presence of 70% aqueous TBHP/30% aqueous H2O2 as a greener oxidant. Generally, these complexes perform better than their mononuclear analogues. Spectroscopy, DFT studies, and isolated intermediates have helped in proposing a suitable reaction mechanism for the catalytic reaction.

Crystal structure and Hirshfeld surface analysis of 2-methyl-quinazolin-4(3H)-one hydro-chloride

The title salt (systematic name: 2-methyl-4-oxo-3,4-dihydroquinazolin-1-ium chloride), C9H9N2O+·Cl-, has ortho-rhom-bic (Pbcm) symmetry. Except for two methyl H atoms, all atoms of the mol-ecular cation are located about a mirror plane, making the quinazolinium moiety exactly planar. Individual mol-ecules are arranged in (001) layers in the crystal. Supra-molecular features include N-H⋯Cl hydrogen-bonding inter-actions, leading to zigzag chains along [010] with D 1 1(2) and C 1 2(6) graph-set motifs. Additionally, weak π-π stacking inter-actions occur between benzene rings in adjacent layers. Hirshfeld surface analysis revealed that the most important contributions to the surface contacts are from H⋯H (36.1%), H⋯C/C⋯H (25.8%), and H⋯O/O⋯H (17.7%) inter-actions.

A Systematic Review of Synthetic and Anticancer and Antimicrobial Activity of Quinazoline/Quinazolin-4-one Analogues

Quinazolines/quinazolin-4-ones are significant nitrogen-containing heterocycles that exist in various natural products and synthetic scaffolds with diverse medicinal and pharmacological applications. Researchers across the globe have explored numerous synthetic strategies to develop safer and more potent quinazoline/quinazolinone analogues, particularly for combating cancer and microbial infections. This review systematically examines scholarly efforts toward understanding this scaffold's synthetic pathways and medicinal relevance, emphasizing the role of metal and non-metal catalysts and other reagents in their synthesis. Additionally, the article discusses selected compounds' anticancer and antimicrobial properties, with a brief look into their structure-activity relationships.

Electrochemical Synthesis of Quinazolines: N-H/C(sp3)-H Coupling of o-Carbonyl Anilines with Amino Acids and Amines

A mild and efficient electrochemical protocol for the synthesis of quinazolines through N-H/C(sp3)-H coupling of o-carbonyl anilines with natural amino acids/amines has been developed. The products quinazolines can easily be isolated in moderate to excellent yields under external chemical oxidant-free conditions. Moreover, this reaction can be safely conducted on gram scale.

A microwave assisted tandem synthesis of quinazolinones using ionic liquid supported copper(II) catalyst with mechanistic insights

Quinazolinone is a preferred structural motif with notable pharmacological activity that is present in a wide range of naturally occurring compounds. A microwave assisted tandem cyclooxidative method has been developed to afford quinazolinones via a recyclable ionic liquid supported copper catalyst. This sustainable method exhibits operational simplicity through a rapid, clean, and energy-efficient route and a variety of 2-substituted quinazolinones are obtained in excellent yields. In addition, this innovative approach enables us to develop a library of nitriles in an environment-friendly synthetic protocol. Moreover, the catalyst can be recycled and reused up to three consecutive cycles without any significant loss of catalytic activity. Further organic transformation of the synthesized quinazolinones was carried out to afford reported as well as novel bioactive heterocyclic compounds.

Green Approach for the Synthesis of 2-Phenyl-2H-indazoles and Quinazoline Derivatives Using Sustainable Heterogeneous Copper Oxide Nanoparticles Supported on Activated Carbon and OER Study

This research work reports the synthesis of copper oxide (CuO) nanoparticles supported on activated carbon by a simple impregnation method using 2-propanol as a green solvent, followed by calcination. The synthesized CuO@C is used as an efficient heterogeneous nanocatalyst for the synthesis of 2H-indazoles and quinazolines utilizing commercially available 2-bromobenzaldehydes, primary amines, and sodium azide under ligand-free and base-free conditions. The present methodology demonstrates the formation of new N-N, C-N, and C═N bonds under one-pot reaction conditions using PEG-400 as a green solvent. The reaction pathways are supported by control experiments and mechanistic elucidation. Further, the synthesized catalyst was characterized by a range of microscopic and spectroscopic techniques such as powdered X-ray diffraction, fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray, UV-vis, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and BET-BJH analysis. Importantly, the study focused on the recyclability of the catalyst and successfully showed gram-scale production. Significantly, our active catalyst exhibited an outstanding performance in the oxygen evolution reaction, with an overpotential of 290 mV and a swallow Tafel slope of 91 mV dec-1.

Benzoquinone Ligand-Enabled Ruthenium-Catalyzed Deaminative Coupling of 2-Aminoaryl Aldehydes and Ketones with Branched Amines for Regioselective Synthesis of Quinoline Derivatives

The catalytic system generated in situ from the cationic Ru-H complex [(C6H6)(PCy3)(CO)RuH]+BF4- (1) with 2,3,4,5-tetrachloro-1,2-benzoquinone (L1) was found to be highly effective for promoting the deaminative coupling reaction of 2-aminoaryl aldehydes with branched amines to form 2-substituted quinoline products. The analogous deaminative coupling reaction of 2-aminoaryl ketones with branched amines led to the regioselective formation of 2,4-disubstituted quinoline products. A number of biologically active quinoline derivatives including graveolinine and a triplex DNA intercalator have been synthesized by using the catalytic method.

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.

p-Toluenesulfonic acid-promoted organic transformations for the generation of molecular complexity

Since the beginning of this century, p-toluenesulfonic acid (p-TSA) catalysed organic transformations have been an active area of research for developing efficient synthetic methodologies. Often, catalysis using p-TSA is associated with many advantages, such as operational simplicity, high selectivity, excellent yields, and ease of product isolation, which make organic synthesis convenient and versatile. Notably, p-TSA is a non-toxic, commercially available, inexpensive solid organic compound that is soluble in water, alcohols, and other polar organic solvents. p-TSA is a strong acid compared to many protic or mineral acids and its high acidity helps activate different organic functional groups. p-TSA-promoted conversions are fast, have a high atom and pot economy, and feature a multiple bond-forming index. Therefore, the utilization of p-TSA enables the synthesis of many important structural scaffolds without any hazardous metals, making it desirable in numerous applications of sustainable and green chemistry. Recently, this emerging area of research has become one of the pillars of synthetic organic chemistry to synthesise biologically relevant, complex carbocycles and heterocycles. This study provides a comprehensive summary of methods, applications, and mechanistic insights into p-TSA-catalysed organic transformations, covering the literature reports that have appeared since 2012.

Visible-light photocatalyzed C-N bond activation of tertiary amines: a three-component approach to synthesize quinazolines

A metal-free three-component approach has been developed to prepare 2,4-disubstituted quinazolines from o-acylanilines, trialkylamines and ammonium chloride under visible-light using eosin Y as the photocatalyst. The notable features of this work include (i) the use of tertiary amines as an alkyl synthon and triethanolamine as a C2-OH synthon; (ii) good functional group tolerance with 52%-98% yields; (iii) proof of concept with o-amino benzaldehyde as a substrate to deliver 2-methyl quinazoline 3pa; and (iv) gram-scale synthesis of compounds 3ga, 3ja and 3ma. A reductive quenching mechanism was proposed based on the control studies and redox potential values.

How Can Deep Eutectic Systems Promote Greener Processes in Medicinal Chemistry and Drug Discovery?

Chemists in the medicinal chemistry field are constantly searching for alternatives towards more sustainable and eco-friendly processes for the design and synthesis of drug candidates. The pharmaceutical industry is one of the most polluting industries, having a high E-factor, which is driving the adoption of more sustainable processes not only for new drug candidates, but also in the production of well-established active pharmaceutical ingredients. Deep eutectic systems (DESs) have emerged as a greener alternative to ionic liquids, and their potential to substitute traditional organic solvents in drug discovery has raised interest among scientists. With the use of DESs as alternative solvents, the processes become more attractive in terms of eco-friendliness and recyclability. Furthermore, they might be more effective through making the process simpler, faster, and with maximum efficiency. This review will be focused on the role and application of deep eutectic systems in drug discovery, using biocatalytic processes and traditional organic chemical reactions, as new environmentally benign alternative solvents. Furthermore, herein we also show that DESs, if used in the pharmaceutical industry, may have a significant effect on lowering production costs and decreasing the impact of this industry on the quality of the environment.

Six-Membered Aromatic Nitrogen Heterocyclic Anti-Tumor Agents: Synthesis and Applications

Cancer stands as a serious malady, posing substantial risks to human well-being and survival. This underscores the paramount necessity to explore and investigate novel antitumor medications. Nitrogen-containing compounds, especially those derived from natural sources, form a highly significant category of antitumor agents. Among these, antitumor agents with six-membered aromatic nitrogen heterocycles have consistently attracted the attention of chemists and pharmacologists. Accordingly, we present a comprehensive summary of synthetic strategies and clinical implications of these compounds in this review. This entails an in-depth analysis of synthesis pathways for pyridine, quinoline, pyrimidine, and quinazoline. Additionally, we explore the historical progression, targets, mechanisms of action, and clinical effectiveness of small molecule inhibitors possessing these structural features.

Green synthesis of quinazoline derivatives using a novel recyclable nano-catalyst of magnetic modified graphene oxide supported with copper

A new magnetic nano-catalyst system based on graphene oxide was designed and manufactured (GO@Fe3O4@3-chloropropyltrimethoxysilane@(Z)-N'-(2-hydroxybenzylidene)-4-(pyridin-4-yl)benzohydrazide@Cu(II)), and it was checked and confirmed by various analyzes such as FTIR, XRD, EDX, MAPPING, TGA/DSC, VSM and FESEM. This nano-catalyst was used in the three-component one-pot synthesis of quinazoline derivatives. The products were obtained using this efficient catalyst with high efficiency in short time and solvent-free conditions. Easy separation and acceptable recyclability are other advantages of this new nano-catalyst. Also, the catalyst can be recycled 4 times without a significant change in its efficiency.

2-Substituted quinazolines: Partial agonistic and antagonistic ligands of the constitutive androstane receptor (CAR)

Following the discovery of 2-(3-methoxyphenyl)-3,4-dihydroquinazoline-4-one and 2-(3-methoxyphenyl)quinazoline-4-thione as potent, but non-specific activators of the human Constitutive Androstane Receptor (CAR, NR1I3), a series of quinazolinones substituted at the C2 phenyl ring was prepared to examine their ability to selectively modulate human CAR activity. Employing cellular and in vitro TR-FRET assays with wild-type CAR or its variant 3 (CAR3) ligand binding domains (LBD), several novel partial human CAR agonists and antagonists were identified. 2-(3-Methylphenyl) quinazolinone derivatives 7d and 8d acted as partial agonists with the recombinant CAR LBD, the former in nanomolar units (EC50 = 0.055 μM and 10.6 μM, respectively). Moreover, 7d did not activate PXR, and did not show any signs of cytotoxicity. On the other hand, 2-(4-bromophenyl)quinazoline-4-thione 7l possessed significant CAR antagonistic activity, although the compound displayed no agonistic or inverse agonistic activities. A compound possessing purely antagonistic effect was thus identified for the first time. These and related compounds may serve as a remedy in xenobiotic intoxication or, conversely, in suppression of undesirable hepatic CAR activation.

Medicinal Chemistry of Quinazolines as Anticancer Agents Targeting Tyrosine Kinases

Cancer is a large group of diseases that can affect any organ or body tissue due to the abnormal cellular growth with the unknown reasons. Many of the existing chemotherapeutic agents are highly toxic with a low level of selectivity. Additionally, they lead to development of therapeutic resistance. Hence, the development of targeted chemotherapeutic agents with low side effects and high selectivity is required for cancer treatment. Quinazoline is a vital scaffold well-known to be linked with several biological activities. The anticancer activity is one of the prominent biological activities of this scaffold. Several established anticancer quinazolines work by different mechanisms on the various molecular targets. The aim of this review is to present different features of medicinal chemistry as drug design, structure activity relationship, and mode of action of some targeted anticancer quinazoline derivatives. It gives comprehensive attention on the chemotherapeutic activity of quinazolines in the viewpoint of drug discovery and its development. This review provides panoramic view to the medicinal chemists for supporting their efforts to design and synthesize novel quinazolines as targeted chemotherapeutic agents.

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.

Application of N,N-Dimethylethanolamine as a One-Carbon Synthon for the Synthesis of Pyrrolo[1,2-a]quinoxalines, Quinazolin-4-ones, and Benzo[4,5]imidazoquinazolines via [5 + 1] Annulation

The synthesis of N-heterocycles composes a significant part of synthetic chemistry. In this report, a Cu(II)-catalyzed green and efficient synthesis of pyrrolo[1,2-a]quinoxaline, quinazolin-4-one, and benzo[4,5]imidazoquinazoline derivatives was developed, employing N,N-dimethylethanolamine (DMEA) as a C1 synthon. Green oxidant O₂ is critical in these transformations, facilitating the formation of a key intermediate─a reactive iminium ion. The method conducted under mild conditions is compatible with a diversity of functional groups, providing an appealing alternative to the previously developed protocols.

Unified Access to Pyrimidines and Quinazolines Enabled by N-N Cleaving Carbon Atom Insertion

Given the ubiquity of heterocycles in biologically active molecules, transformations with the capacity to modify such molecular skeletons with modularity remain highly desirable. Ring expansions that enable interconversion of privileged heterocyclic motifs are especially interesting in this regard. As such, the known mechanisms for ring expansion and contraction determine the classes of heterocycle amenable to skeletal editing. Herein, we report a reaction that selectively cleaves the N–N bond of pyrazole and indazole cores to afford pyrimidines and quinazolines, respectively. This chlorodiazirine-mediated reaction provides a unified route to a related pair of heterocycles that are otherwise typically prepared by divergent approaches. Mechanistic experiments and DFT calculations support a pathway involving pyrazolium ylide fragmentation followed by cyclization of the ring-opened diazahexatriene intermediate to yield the new diazine core. Beyond enabling access to valuable heteroarenes from easily prepared starting materials, we demonstrate the synthetic utility of skeletal editing in the synthesis of a Rosuvastatin analog as well as in an aryl vector-adjusting direct scaffold hop.

Rh(III)-Catalyzed Tandem Reaction Access to (Quinazolin-2-yl)methanone Derivatives from 2,1-Benzisoxazoles and α-Azido Ketones

A Rh(III)-catalyzed tandem reaction for the synthesis of (quinazolin-2-yl)methanone derivatives has been explored from 2,1-benzisoxazoles and α-azido ketones. The transformation involves Rh(III)-catalyzed denitrogenation of α-azido ketones, aza-[4 + 2] cycloaddition, ring opening, and dehydration aromatization processes. Notably, the aza-[4 + 2] cycloaddition of an imine rhodium complex intermediate with 2,1-benzisoxazoles is the key to this reaction.

Synthesis of Flavanone and Quinazolinone Derivatives from the Ruthenium-Catalyzed Deaminative Coupling Reaction of 2'-Hydroxyaryl Ketones and 2-Aminobenzamides with Simple Amines

The cationic Ru-H complex [(C₆H₆)(PCy₃)(CO)RuH]⁺BF₄^- (1) with 3,4,5,6-tetrachloro-1,2-benzoquinone (L1) was found to be a highly effective catalyst for the deaminative coupling reaction of 2'-hydroxyaryl ketones with simple amines to form 3-substituted flavanone products. The analogous deaminative coupling reaction of 2-aminobenzamides with branched amines directly formed 3,3-disubstituted quinazolinone products. The catalytic method efficiently installs synthetically useful flavanone and quinazolinone core structures without employing any reactive reagents.

Copper-Catalyzed One-Pot Synthesis of Quinazolinones from 2-Nitrobenzaldehydes with Aldehydes: Application toward the Synthesis of Natural Products

A novel, efficient, and atom-economical approach for the construction of quinazolinones from 2-nitrobenzaldehydes has been unveiled via copper-catalyzed nitrile formation, hydrolysis, and reduction in one pot for the first time. In this reaction, urea is used as a source of nitrogen for nitrile formation, hydrazine hydrate is used for both the reduction of the nitro group and the hydrolysis of nitrile, and atmospheric oxygen is used as the sole oxidant. The method portrays a wide substrate scope with good functional group tolerances. Moreover, this method was applied for the synthesis of schizocommunin, tryptanthrin, phaitanthrin-A, phaitanthrin-B, and 8H-quinazolino[4,3-b]quinazolin-8-one.

N,N-Dimethylformamide as Carbon Synthons for the Synthesis of N-Heterocycles: Pyrrolo/Indolo[1,2-a]quinoxalines and Quinazolin-4-ones

N,N-dimethylformamide (DMF) as synthetic precursors contributing especially the methyl, acyl, and amino groups has played a significant role in heterocycle syntheses and functionalization. In this protocol, a wide range of pyrrolo/indolo[1,2-a]quinoxalines and quinazolin-4-ones were obtained in moderate to good yields by using elemental iodine without any metal or peroxides. We considered that N-methyl and N-acyl of DMF participate and complete the reaction separately through different mechanisms, which displayed potential still to be explored of DMF.

α-Keto Acids as Triggers and Partners for the Synthesis of Quinazolinones, Quinoxalinones, Benzooxazinones, and Benzothiazoles in Water

A general and efficient method for the synthesis of quinazolinones, quinoxalinones, benzooxazinones, and benzothiazoles from the reactions of α-keto acids with 2-aminobenzamides, benzene-1,2-diamines, 2-aminophenols, and 2-aminobenzenethiols, respectively, is described. The reactions were conducted under catalyst-free conditions, using water as the sole solvent with no additive required, and successfully applied to the synthesis of sildenafil. More importantly, these reactions can be conducted on a mass scale, and the products can be easily purified through filtration and washing with ethanol (or crystallized).

Nickel catalyzed sustainable synthesis of benzazoles and purines via acceptorless dehydrogenative coupling and borrowing hydrogen approach

Herein we report nickel-catalyzed sustainable synthesis of a few chosen five-membered fused nitrogen heterocycles such as benzimidazole, purine, benzothiazole, and benzoxazole via acceptorless dehydrogenative functionalization of alcohols. Using a bench stable, easy to prepare, and inexpensive Ni(ii)-catalyst, [Ni(MeTAA)] (1a), featuring a tetraaza macrocyclic ligand (tetramethyltetraaza[14]annulene (MeTAA)), a wide variety of polysubstituted benzimidazole, purine, benzothiazole, and benzoxazole derivatives were prepared via dehydrogenative coupling of alcohols with 1,2-diaminobenzene, 4,5-diaminopyrimidine, 2-aminothiphenol, and 2-aminophenol, respectively. A wide array of benzimidazoles were also prepared via a borrowing hydrogen approach involving alcohols as hydrogen donors and 2-nitroanilines as hydrogen acceptors. A few control experiments were performed to understand the reaction mechanism.

Electrochemical access to benzimidazolone and quinazolinone derivatives via in situ generation of isocyanates

Isocyanates are the key intermediates for several organic transformations towards the synthesis of diverse pharmaceutical targets. Herein, we report the development of an oxidant-free protocol for electrochemical in situ generation of isocyanates. This strategy highlights expedient access to benzimidazolones and quinazolinones and eliminates the need for exogenous oxidants. Furthermore, detailed mechanistic studies provide strong support towards our hypothesis of in situ isocyanate generation.

Reframing primary alkyl amines as aliphatic building blocks

While primary aliphatic amines are ubiquitous in natural products, they are traditionally considered inert to substitution chemistry. This review highlights historical and recent advances in the field of aliphatic deamination chemistry which demonstrate these moieties can be harnessed as valuable C(sp3) synthons. Cross-coupling and photocatalyzed transformations proceeding through polar and radical mechanisms are compared with oxidative deamination and other transition metal catalyzed reactions.

Improved, gram-scale synthesis of sildenafil in water using arylacetic acid as the acyl source in the pyrazolo[4,3-d]pyrimidin-7-one ring formation

An improved, gram-scale synthesis of the blockbuster drug sildenafil, used for the treatment of male erectile dysfunction, has been developed.

An efficient transition-metal-free route to quinazolin-4(3H)-ones via 2-aminobenzamides and thiols

An efficient approach to quinazolin-4(3H)-ones was developed by a one-pot intermolecular annulation reaction of o-amino benzamides and thiols.

Visible-light induced copper(i)-catalyzed oxidative cyclization of o-aminobenzamides with methanol and ethanol via HAT

The use of the in situ generated ligand-copper superoxo complex absorbing light energy to activate the alpha C(sp³)-H of MeOH and EtOH via the hydrogen atom transfer (HAT) process for the synthesis of quinazolinones by oxidative cyclization of alcohols with o-aminobenzamide has been investigated. The synthetic utility of this protocol offers an efficient synthesis of a quinazolinone intermediate for erlotinb (anti-cancer agent) and 30 examples were reported.