- Towards a Sequential One-Pot Preparation of 1,2,3-Benzotriazin-4(3H)-ones Employing a Key Cp*Co(III)-catalyzed C?H Amidation Step
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1,2,3-benzotriazin-4(3H)-one derivatives have been recognised for their potential application as pesticides and pharmaceuticals and new methodologies for their preparation, starting from readily accessible reagents would therefore be an attractive proposition. A wide range of differently substituted benzamides are readily available, which provide an excellent substrate scaffold for the application of direct C?H functionalization protocols. In this context, herein we report the use of a Cp*Co(III) catalyst for the amidation of these benzamides, using 1,4,2-dioxazol-5-ones as amidating agent. The isolable intermediate 2-acetamido benzamide products can thereafter be converted to the desired 1,2,3-benzotriazin-4(3H)-one derivatives through the use of tert-butyl nitrite under mild conditions. It was found to be possible to perform the second step with the crude reaction mixture obtained from the initial C?H amidation step, leading to the overall development of a facile one-pot procedure for the preparation of a range of substituted 1,2,3-benzotriazin-4(3H)-one derivatives, requiring only 5 hours of reaction time, which is also applicable on a gram scale. In addition, the key Cp*Co(III)-catalyzed C?H amidation step has been studied by DFT calculations in order to fully elucidate the mechanism. (Figure presented.).
- Chirila, Paula G.,Skibinski, Lauren,Miller, Keith,Hamilton, Alex,Whiteoak, Christopher J.
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p. 2324 - 2332
(2018/04/30)
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- Synthesis of N -Heteropolycyclic Compounds Including Quinazolinone Skeleton Using Friedel-Crafts Alkylation
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A simple method to synthesize N-heteropolycyclic quinazolinones was developed including Knoevenagel condensation of quinazolines and aldehydes and Friedel-Craft alkylation as key steps. Knoevenagel reaction of 2-methyl-3-phenylquinazolin-4(3H)-one proceeded smoothly under a basic condition and subsequent Friedel-Craft alkylation with Bronsted acid gave the N-heteropolycyclic quinazolinones in good yields. Furthermore, these new polycyclic compounds were converted into organic molecules having a long π-conjugation system by treatment of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) to utilize them as organic dyes. GRAPHICAL ABSTRACT.
- Oh, Bu Keun,Ko, Eun Bi,Han, Jin Wook,Oh, Chang Ho
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p. 768 - 776
(2015/10/29)
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- Quinazolin-4-one derivatives as selective histone deacetylase-6 inhibitors for the treatment of Alzheimer's disease
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Novel quinazolin-4-one derivatives containing a hydroxamic acid moiety were designed and synthesized. All compounds were subjected to histone deacetylase (HDAC) enzymatic assays to identify selective HDAC6 inhibitors with nanomolar IC50 values. (E)-3-(2-Ethyl-7-fluoro-4-oxo-3-phenethyl-3,4- dihydroquinazolin-6-yl)-N-hydroxyacrylamide, 4b, is the most potent HDAC6 inhibitor (IC50, 8 nM). In vitro, these compounds induced neurite outgrowth accompanied by growth-associated protein 43 expression, and they enhanced the synaptic activities of PC12 and SH-SY5Y neuronal cells without producing toxic or mitogenic effects. Several of the compounds dramatically increased nonhistone protein acetylation, specifically of α-tubulin. Some of the more potent HDAC6 inhibitors decreased zinc-mediated β-amyloid aggregation in vitro. N-Hydroxy-3-(2-methyl-4-oxo-3-phenethyl-3,4-dihydro- quinazolin-7-yl)-acrylamide, 3f, the most promising drug candidate, selectively inhibits HDAC6 (IC50, 29 nM), practically does not affect human ether-a-go-go-related membrane channel activity (IC50 >10 μM) or cytochrome P450 activity (IC50 >6.5 μM) in vitro, and significantly improves learning-based performances of mice with β-amyloid-induced hippocampal lesions.
- Yu, Chao-Wu,Chang, Pei-Teh,Hsin, Ling-Wei,Chern, Ji-Wang
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p. 6775 - 6791
(2013/10/01)
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- Expedient Synthesis of N-acyl anthranilamides and β-enamine amides by the Rh(III)-catalyzed amidation of aryl and vinyl C-H bonds with isocyanates
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A Rh(III)-catalyzed protocol for the amidation of anilide and enamide C-H bonds with isocyanates has been developed. This method provides direct and efficient syntheses of N-acyl anthranilamides, enamine amides, and pyrimidin-4-one heterocycles.
- Hesp, Kevin D.,Bergman, Robert G.,Ellman, Jonathan A.
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supporting information; experimental part
p. 11430 - 11433
(2011/10/02)
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- Synthesis and Rearrangement of 4-Imino-4H-3,1-benzoxazines
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N-Acylanthranilamides react with dibromotriphenylphosphorane in the presence of triethylamine as HBr captor to give 4-imino-4H-3,1-benzoxazines in good yields.If the reaction is carried out without acid acceptor, N-acetylanthranilamides yield 2-methyl-4-q
- Mazurkiewicz, Roman
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p. 973 - 980
(2007/10/02)
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