The Synthesis of Quinazolinones from Olefins, CO, and Amines over a Heterogeneous Ru-clusters/Ceria Catalyst

Predesign of Covalent-Organic Frameworks for Efficient Photocatalytic Dehydrogenative Cross-Coupling Reaction

The dehydrogenative cross-coupling reaction is the premier route for synthesizing important 4-quinazolinone drugs. However, it usually requires high reaction temperature and long reaction time, and the yield of the final product is low. Here two stable and photosensitive covalent-organic frameworks (COFs), TAPP-An and TAPP-Cu-An are purposefully designed and constructed to serve as unprecedented heterogeneous tandem catalysts to complete dehydrogenative cross-coupling reactions in a short time and under mild reaction conditions (room temperature and light), leading to the high-efficient photosynthesis of 4-quinazolinones. Particularly, TAPP-Cu-An is the best heterogeneous catalyst currently available for the synthesis of 4-quinazolinones, even surpassing all the catalysts reported so far. It also enables one-step photosynthesis of 4-quinazolinones with higher conversion (>99%) and selectivity (>99%) in a shorter time, and the product can be easily prepared on a gram scale. Extensive experiments combined with theoretical calculations show that the excellent photogenerated charge separation and transport capability, as well as the synergistic An-Cu catalysis in TAPP-Cu-An are the main driving forces for this efficient reaction.

Antiproliferative metabolites against glioma cells from the marine-associated actinomycete Streptomyces sp. ZZ735

Metabolites produced by the genus Streptomyces are the most important resource for discovering bioactive compounds. In this study, chemical investigation on the metabolites produced by the marine-derived Streptomyces sp. ZZ735 in rice solid medium led to the isolation of eighteen compounds (1-18). Chemical structures of the isolated compounds were determined based on their HRESIMS data and the extensive NMR spectral analyses. Streptonaphthothiazines A (1), B (2), 2-(2-hydroxy-2-methylpropanoylamino)-benzoic acid (7), and streptomycinoic acids A (17), B (18) are characterized as five previously undescribed compounds. The structural backbones of streptonaphthothiazines A (1), B (2) and streptomycinoic acids A (17), B (18) are found from a natural resource for the first time. It is also the first report of 2-(2-methylpropanoylamino)-benzoic acid (3), 2-(2-methylpropanoylamino)-benzamide (4), methyl 2-(3-hydroxypropanoylamino)-benzoate (5), 2-propionylaminobenzamide (6), and (2E)-3-(3-hydroxy-4,5-dimethoxyphenyl)-2-propenoic acid (15) as natural products. Streptonaphthothiazines A (1), B (2) and streptomycinoic acids A (17), B (18) have antiproliferative activity against human glioma U87MG or U251 cells with IC50 values ranging from 31.8 to 37.9 μM.

Ambient-pressure alkoxycarbonylation for sustainable synthesis of ester

Alkoxycarbonylation reactions are common in the chemical industry, yet process sustainability is limited by the inefficient utilization of CO. In this study, we address this issue and demonstrate that significant improvements can be achieved by adopting a heterogeneously catalyzed process, using a Ru/NbOx catalyst. The Ru/NbOx catalyst enables the direct synthesis of methyl propionate, a key industrial commodity, with over 98% selectivity from CO, ethylene and methanol, without any ligands or acid/base promoters. Under ambient CO pressure, a high CO utilization efficiency (336 mmolestermolCO-1h-1) is achieved. Mechanistic investigations reveal that CO undergoes a methoxycarbonyl (COOCH3) intermediate pathway, attacking the terminal carbon atom of alkene and yielding linear esters. The origins of prevailing linear regioselectivity in esters are revealed. The infrared spectroscopic feature of the key COOCH3 species is observed at 1750 cm-1 (C=O vibration) both experimentally and computationally. The broad substrate applicability of Ru/NbOx catalyst for ester production is demonstrated. This process offers a sustainable and efficient approach with high CO utilization and atom economy for the synthesis of esters.

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.

Synergy of Oxygen Vacancies and Base Sites for Transfer Hydrogenation of Nitroarenes on Ceria Nanorods

CeO2 nanorod based catalysts for the base-free synthesis of azoxy-aromatics via transfer hydrogenation of nitroarenes with ethanol as hydrogen donor have been synthesized and investigated. The oxygen vacancies (Ov ) and base sites are critical for their excellent catalytic properties. The Ov , i.e., undercoordinated Ce cations, serve as the sites to activate ethanol and nitroarenes by lowering the energy barrier to transfer hydrogen from α-Csp3 -H in ethanol to the nitro group coupling it to the redox reactions between Ce3+ and Ce4+ . At the same time, the base sites catalyze the condensation step to selectively produce azoxy-aromatics. The catalytic route opens a much improved way to use non-noble metal oxides without additives for the selective functional group reduction and coupling reactions.

A Direct Method for Synthesis of Quinoxalines and Quinazolinones Using Epoxides as Alkyl Precursor

An iodine-mediated one-pot synthesis of pyrrolo/indolo [1,2-a]quinoxalines and quinazolin-4-one via utilizing epoxides as alkyl precursors under metal-free conditions has been described. Both 1-(2-aminophenyl)-pyrrole and 2-aminobenzamide could be applied to this protocol. A total of 33 desired products were obtained with moderate to good yields. This methodology was suitable for wide-scale preparation and the obtained products could be further modified into promising pharmaceutically active reagents.

Synthesis, antitumor activity, 3D-QSAR and molecular docking studies of new iodinated 4-(3H)-quinazolinones 3N-substituted

A novel series of 6-iodo-2-methylquinazolin-4-(3H)-one derivatives, 3a–n, were synthesized and evaluated for their in vitro cytotoxic activity. Compounds 3a, 3b, 3d, 3e, and 3h showed remarkable cytotoxic activity on specific human cancer cell lines when compared to the anti-cancer drug, paclitaxel. Compound 3a was found to be particularly effective on promyelocytic leukaemia HL60 and non-Hodgkin lymphoma U937, with IC₅₀ values of 21 and 30 μM, respectively. Compound 3d showed significant activity against cervical cancer HeLa (IC₅₀ = 10 μM). The compounds 3e and 3h were strongly active against glioblastoma multiform tumour T98G, with IC₅₀ values of 12 and 22 μM, respectively. These five compounds showed an interesting cytotoxic activity on four human cancer cell types of high incidence. The molecular docking results reveal a good correlation between experimental activity and calculated binding affinity on dihydrofolate reductase (DHFR). Docking studies proved 3d as the most potent compound. In addition, the three-dimensional quantitative structure–activity relationship (3D-QSAR) analysis exhibited activities that may indicate the existence of electron-withdrawing and lipophilic groups at the para-position of the phenyl ring and hydrophobic interactions of the quinazolinic ring in the DHFR active site.

New iodinated 4-(3H)-quinazolinones 3N-substituted with antitumor activity and 3D-QSAR and molecular docking studies as dihydrofolate reductase (DHFR) inhibitors.

tert-Butyl Hydroperoxide Promoted the Reaction of Quinazoline-3-oxides with Primary Amines Affording Quinazolin-4(3H)-ones

An efficient and facile approach for the synthesis of quinazolin-4(3H)-ones via the reaction of quinazoline-3-oxides with primary amines is described. This approach is demonstrated to be applicable for a broad range of substrates and proceeds efficiently under metal-free and mild reaction conditions employing easily available tert-butyl hydroperoxide as the oxidant. Remarkably, 3-(2-(1H-indol-3-yl) ethyl)quinazolin-4(3H)-one 3w, which was conveniently obtained by this process in 70% yield, was an excellent precursor for the synthesis of bioactive evodiamine and rutaempine.

Recent Progress of Metal Nanoparticle Catalysts for C–C Bond Forming Reactions

Over the past few decades, the use of transition metal nanoparticles (NPs) in catalysis has attracted much attention and their use in C–C bond forming reactions constitutes one of their most important applications. A huge variety of metal NPs, which have showed high catalytic activity for C–C bond forming reactions, have been developed up to now. Many kinds of stabilizers, such as inorganic materials, magnetically recoverable materials, porous materials, organic–inorganic composites, carbon materials, polymers, and surfactants have been utilized to develop metal NPs catalysts. This review classified and outlined the categories of metal NPs by the type of support.

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.

Rhodium-Catalyzed Merging of 2-Arylquinazolinone and 2,2-Difluorovinyl Tosylate: Diverse Synthesis of Monofluoroolefin Quinazolinone Derivatives

An efficient method for the synthesis of 2-(o-monofluoroalkenylaryl)quinazolinone derivatives was developed. In this context, the quinazolinone ring served as the inherent directing group, 2,2-difluorovinyl tosylate was used as the monofluoroolefin synthon, and Rh(III)-catalyzed C-H bond difluorovinylation of 2-arylquinazolinons was performed to give the corresponding monofluoroalkene-containing quinazolinons in yields of 65-92%. The method is characterized by broad synthetic utility, mild conditions, and high efficiency.

Copper-Catalyzed Oxidative Multicomponent Annulation Reaction for Direct Synthesis of Quinazolinones via an Imine-Protection Strategy

Via an imine-protection strategy, we herein present an unprecedented copper-catalyzed oxidative multicomponent annulation reaction for direct synthesis of quinazolinones. The construction of various products is achieved via formation of three C-N and one C-C bonds in conjunction with the benzylic functionalization. The merits of easily available feedstocks, naturally abundant catalyst, good functional group and substrate compatibility, and release of H₂O as the byproduct make the developed chemistry a practical way to access quinazolinones.