Amino acids as the nitrogen-containing motifs in copper-catalyzed domino synthesis of N-heterocycles

Photogenerated chlorine radicals activate C(sp3)-H bonds of alkylbenzenes to access quinazolinones

An Fe-catalyzed visible-light induced condensation of alkylbenzenes with anthranilamides has been developed. Upon irradiation, the trivalent iron complex could generate chlorine radicals, which successfully abstracted the hydrogen of benzylic C-H bonds to form benzyl radicals. And these benzyl radicals were converted into oxygenated products under air conditions, which subsequently reacted with anthranilamides for the synthesis of quinazolinones.

H2O2-Mediated Synthesis of a Quinazolin-4(3H)-one Scaffold: A Sustainable Approach

A quinazolin-4(3H)-one ring system is a privileged heterocyclic moiety with distinctive biological properties. From this perspective, the development of an efficient strategy for the synthesis of quinazolin-4(3H)-one has always been in demand for the synthetic chemistry community. In this report, we envisaged an efficient protocol for the synthesis of quinazolin-4(3H)-one using substituted 2-amino benzamide with dimethyl sulfoxide (DMSO) as a carbon source and H2O2 as an effective oxidant. Mechanistically, the reaction proceeds through the radical approach with DMSO as one carbon source. To further substantiate the synthetic claim, the synthetic protocol has been extended to the synthesis of the anti-endotoxic active compound 3-(2-carboxyphenyl)-4-(3H)-quinazolinone.

A direct entry to polycyclic quinoxaline derivatives via I2-DMSO mediated oxidative decarboxylation of α-amino acids and the subsequent Pictet-Spengler cyclization reaction

A facile and highly efficient iodine-promoted strategy has been delineated for the synthesis of indolo and pyrrolo[1,2-a]quinoxaline derivatives via an oxidative Pictet-Spengler type amino cyclo-annulation reaction using ∝-amino acids as aldehyde surrogates. The concomitant benzylic oxidation and the compatibility of different starting materials under standard conditions made the current method versatile. The salient features of the protocol such as readily available starting materials, inexpensive promoters, environmental benignity, broad substrate scope, scalability, and good to excellent yield make the method more attractive to practitioners of organic synthesis.

DMSO as a Dual Carbon Synthon in One-pot Tandem Synthesis of N-alkylated Quinazolinones from Anthranilamides and Acetophenones

A new, efficient, metal-free, and DMSO intervened approach for the synthesis of N-alkylated quinazolinones from readily available 2-aminobenzamide and aryl methyl ketones in the presence of an oxidizing agent has...

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...

Synthesis of N-Heterocycles via Oxidant-Free Dehydrocyclization of Alcohols Using Heterogeneous Catalysts

N-Heterocycles, such as pyrroles, pyrimidines, quinazolines, and quinoxalines, are important building blocks for organic chemistry and the fine-chemical industry. For their synthesis, catalytic borrowing hydrogen and acceptorless dehydrogenative coupling reactions of alcohols as sustainable reagents have received significant attention in recent years. To overcome the problems of product separation and catalyst reusability, several metal-based heterogeneous catalysts have been reported to achieve these transformations with good yields and selectivity. In this Minireview, we summarize recent developments using both noble and non-noble metal-based heterogeneous catalysts to synthesize N-heterocycles from alcohols and N-nucleophiles via acceptorless dehydrogenation or borrowing hydrogen methodologies. Furthermore, this Minireview introduces strategies for the preparation and functionalization of the corresponding heterogeneous catalysts, discusses the reaction mechanisms and the roles of metal electronic states, and the influence of support Lewis acid-base properties on these reactions.

Access to 2-arylquinazolines via catabolism/reconstruction of amino acids with the insertion of dimethyl sulfoxide

Quinazoline skeletons are synthesized by amino acid catabolism/reconstruction combined with the insertion/cyclization of dimethyl sulfoxide for the first time. The amino acid acts as a carbon and nitrogen source through HI-mediated catabolism and is then reconstructed using aromatic amines and dimethyl sulfoxide (DMSO) as a one-carbon synthon. This protocol is of great significance for the further study of the conversion of amino acids.

Electrochemical synthesis of quinazolinone via I2-catalyzed tandem oxidation in aqueous solution

The development of protocols for synthesizing quinazolinones using biocompatible catalysts in aqueous medium will help to resolve the difficulties of using green and sustainable chemistry for their synthesis. Herein, using I₂ in coordination with electrochemical synthesis induced a C-H oxidation reaction which is reported when using water as the environmentally friendly solvent to access a broad range of quinazolinones at room temperature. The reaction mechanism strongly showed that I₂ cooperates electrochemically promoted the oxidation of alcohols, then effectively cyclizing amides to various quinazolinones.

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.

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.

Switchable and efficient conversion of 2-amido-aryl oxazolines to quinazolin-4(3H)-ones and N-(2-chloroethyl)benzamides

Switchable chemoselective conversion of 2-amido-aryl oxazolines to quinazolin-4(3H)-ones or N-(2-chloroethyl)benzamides is achieved.

Lewis-acid-promoted cyclization reaction: synthesis of N3-chloroethyl and N3-thiocyanatoethyl quinazolinones

A Lewis-acid-promoted cyclization reaction of benzoyl chlorides with 2-(4,5-dihydrooxazol-2-yl)anilines, which can offer a series of N3-chloroethyl quinazolinones, is disclosed.

Microwave-Assisted Synthesis of Quinazolines and Quinazolinones: An Overview

Microwave irradiation (MWI), as a unique, effective, sustainable, more economic, and greener source of energy compared to conventional heating, is applied in different organic transformations to result in the rapid formation of desired compounds due to thermal/kinetic effects. In this review, we try to underscore the applications of microwave irradiation (MWI) in the synthesis of quinazoline and quinazolinone derivatives that have been achieved and reported on in the last two decades.

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.

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.

Protein-Rich Biomass Waste as a Resource for Future Biorefineries: State of the Art, Challenges, and Opportunities

Protein-rich biomass provides a valuable feedstock for the chemical industry. This Review describes every process step in the value chain from protein waste to chemicals. The first part deals with the physicochemical extraction of proteins from biomass, hydrolytic degradation to peptides and amino acids, and separation of amino acid mixtures. The second part provides an overview of physical and (bio)chemical technologies for the production of polymers, commodity chemicals, pharmaceuticals, and other fine chemicals. This can be achieved by incorporation of oligopeptides into polymers, or by modification and defunctionalization of amino acids, for example, their reduction to amino alcohols, decarboxylation to amines, (cyclic) amides and nitriles, deamination to (di)carboxylic acids, and synthesis of fine chemicals and ionic liquids. Bio- and chemocatalytic approaches are compared in terms of scope, efficiency, and sustainability.

Synthesis of quinazolin-4(1H)-ones via amination and annulation of amidines and benzamides

Quinazolinones have broad applications in the biological, pharmaceutical and material fields. Studies on the synthesis of these compounds are therefore widely conducted. Herein, a novel and highly efficient copper-mediated tandem C(sp2)-H amination and annulation of benzamides and amidines for the synthesis of quinazolin-4(1H)-ones is proposed. This synthetic route can be useful for the construction of quinazolin-4(1H)-one frameworks.

Copper-catalyzed tandem oxidative synthesis of quinazolinones from 2-aminobenzonitriles and benzyl alcohols

A highly efficient, one-pot Cu(OAc)₂/Cs₂CO₃-catalyzed protocol for the aerobic oxidative synthesis of quinazolinones from readily available benzyl alcohols and 2-aminobenzonitriles with molecular oxygen as the terminal oxidant has been successfully developed.

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

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

Synthesis and evaluation of chalcone analogues containing a 4-oxoquinazolin-2-yl group as potential anti-tumor agents

The chalcone motif can be found in many molecules that contribute to essential biological processes, and many chalcone-containing compounds exhibit potent anti-cancer activity. Here, we synthesized two series of chalcone analogues (3a-s and 6a-s) based on substituting the chalcone B-ring or A-ring with a 4-oxoquinazolin-2-yl group, and then evaluated them for cytotoxic activity in human colorectal HCT-116 and breast cancer MCF-7 cell lines. Compounds 3a-s (in which a 4-oxoquinazolin-2-yl group functioned as the B-ring) were markedly more cytotoxic than compounds 6a-s (in which 4-oxoquinazolin-2-yl group functioned as the A-ring), based on their IC₅₀ values to inhibit proliferation. Compound 3f was found as the most potent among 38 analogues and the mechanism of its cytotoxicity was investigated. Flow cytometry indicated that HCT-116 cells treated with compound 3f resulted in a dose-dependent accumulation of cells in the sub-G1 phase, which is representative of apoptotic cells. Subsequent assays (including Annexin V-FITC/PI, AO-EB, MitoSOX™ Red and JC-1 staining) confirmed that 3f exposure induced apoptosis in HCT-116 cells. Immunoblotting analysis indicated that cellular exposure to 3f increased the cleavage of PARP1 and caspases 3, 7, and 9. Taken together, this novel chalcone analogue has a cytotoxic effect on cultured cancer cell-lines that is likely mediated by inducing apoptosis via the mitochondrial death pathway.

Bismuth-Catalyzed Synthesis of 2-Substituted Quinazolinones

The bismuth-catalyzed oxidative condensation of aldehydes with 2-aminobenzamide under aerobic conditions is reported using ethanol as the solvent. Good to excellent isolated yields (68-95%) of the corresponding 2-substituted quinazolinones were obtained under mild reaction conditions with excellent functional group tolerance. The quinazolinones were further functionalized to afford N-allylated quinazolinones, 2-aminopyridine derivatives, and annulated polyheterocyclic compounds via transition-metal catalyzed reactions.

"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.

Decarboxylative Annulation of α-Amino Acids with β-Ketoaldehydes

Indolizidine and quinolizidine derivatives are readily assembled from l-proline or (±)-pipecolic acid and β-ketoaldehydes via a decarboxylative annulation process. These reactions are promoted by acetic acid and involve azomethine ylides as reactive intermediates.