- Cleavage of Pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with Thiocarbonohydrazide. Synthesis of Substituted 4-Amino-1,2,4-triazines
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3-Acylpyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones reacted with thiocarbonohydrazide to give mixtures of 4-amino-6-(acylmethyl)-3-sulfanylidene-3,4-dihydro-1,2,4-triazin-5(2H)-ones and 6-substituted 1,4-benzoxazine-2,3-diones which can be separated by fractional crystallization directly from the reaction mixture. The reaction is likely to involve a sequence of nucleophilic transformations with intermediate formation of spiro[pyrrole-2,6′-[1,2,4]triazines] which undergo cleavage of the C2-N1 bond in the pyrrole ring. The structure of the products was determined by X-ray analysis, and intermediate products were identified by UPLC/MS. 1,2,4-Triazine derivatives can also be synthesized independently from alkyl 2,4-dioxobutanoates or 2-oxobutanedioic acid and thiocarbonohydrazide. The known procedure for the synthesis of 4-amino-1,2,4-triazines from 4-aryl-2,4-dioxobutanoic acids and thiocarbonohydrazide was improved to meet the “green chemistry” principles. Two new methods for the synthesis of substituted 4-amino-1,2,4-triazines were developed. The obtained compounds attract interest for medicinal chemistry, pharmacology, and fine organic synthesis.
- Kobelev,Stepanova,Dmitriev,Maslivets
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- Design, synthesis and antimycobacterial activity of benzoxazinone derivatives and open-ring analogues: Preliminary data and computational analysis
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This study examines in depth benzoxazine nucleus for antimycobacterial property. We synthesized some benzoxazin-2-one and benzoxazin-3-one derivatives, which were tested for activity against a panel of Mycobacterium tuberculosis (Mtb) strains, including H37Ra, H37Rv and some resistant strains. Several compounds displayed a high antimycobacterial activity and the three isoniazid analogue derivatives 8a-c exhibited a MIC range of 0.125–0.250 μg/mL (0.37–0.75 μM) against strain H37Ra, therefore lower than the isoniazid reference drug. Two benzoxazin-2-one derivatives, 1c and 5j, together with isoniazid-analogue compound 8a, also revealed low MIC values against resistant strains and proved highly selective for mycobacterial cells, compared to mammalian Vero cells. To predict whether molecule 8a is able to interact with the active site of InhA, we docked it into the crystal structure; indeed, during the molecular dynamic simulation the compound never left the protein pocket. The more active compounds were predicted for ADME properties and all proved to be potentially orally active in humans.
- Zampieri, Daniele,Mamolo, Maria Grazia,Filingeri, Julia,Fortuna, Sara,De Logu, Alessandro,Sanna, Adriana,Zanon, Davide
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supporting information
p. 2468 - 2474
(2019/07/30)
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- Rationalization of benzazole-2-carboxylate versus benzazine-3-one/ benzazine-2,3-dione selectivity switch during cyclocondensation of 2-aminothiophenols/phenols/anilines with 1,2-biselectrophiles in aqueous medium
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The cyclocondensation reaction of 2-aminothiophenols with 1,2-biselectrophiles such as ethyl glyoxalate and diethyl oxalate in aqueous medium leads to the formation of benzothiazole-2-carboxylates via the 5-endo-trig process contrary to Baldwin's rule. On the other hand, the reaction of 2-aminophenols/anilines produced the corresponding benzazine-3-ones or benzazine-2,3-diones via the 6-exo-trig process in compliance with Baldwin's rule. The mechanistic insights of these cyclocondensation reactions using the hard-soft acid-base principle, quantum chemical calculations (density functional theory), and orbital interaction studies rationalize the selectivity switch of benzothiazole-2-carboxylates versus benzazine-3-ones/ benzazine-2,3-diones. The presence of water facilitates these cyclocondensation reactions by lowering of the energy barrier.
- Dhameliya, Tejas M.,Chourasiya, Sumit S.,Mishra, Eshan,Jadhavar, Pradeep S.,Bharatam, Prasad V.,Chakraborti, Asit K.
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p. 10077 - 10091
(2018/05/31)
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- Ytterbium triflate catalyzed heterocyclization of 1,2-phenylenediamines and alkyl oxalates under solvent-free conditions via phillips reaction: A facile synthesis of quinoxaline-2,3-diones derivatives
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Ytterbium triflate are found to catalyze efficiently the Phillips-type heterocyclization reactions of 1,2-phenylenediamine and alkyl oxalate under solvent-free and mild conditions to afford the corresponding quinoxaline-2,3-dione derivatives in high yields. The catalyst could be recovered almost quantitatively from the aqueous layer after the reaction was completed and it could be reused in subsequent reaction without decrease in activity.
- Wang, Limin,Liu, Jijun,Tian, He,Qian, Changtao
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p. 1349 - 1357
(2007/10/03)
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- Synthesis of new [1,2,3]triazoles and 1H-tetrazoles via reactions of 3,(5)-(Di)chloro-2H-1,4-(benz)oxazin-2-ones with diazocompounds or sodium azide
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Treatment of 3,(5)-(di)chloro-2H-1,4-(benz)oxazin-2-ones with diazo compounds or sodium azide yields bi(tri)cyclic compounds which can be converted into [1,2,3]triazoles or 1,5-disubstituted tetrazoles via reactions with nucleophiles as methanol, water and amines.
- Medaer, Bart,Van Aken, Koen,Hoornaert, Georges
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p. 9767 - 9770
(2007/10/02)
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- Syntheses of Cyclic Hydroxamic Acids and Lactams with 2,3-Dioxo-1,4-benzoxazine Skeleton
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Ethyl 2-nitrophenyl oxalate (1a) and its 5-methoxy derivative (1b) were subjected to catalytic hydrogenations over 3percent Pt (S) on carbon in different solvents.Thus, hydrogenation in acetic acid yielded 4-hydroxy-2,3-dioxo-1,4-benzoxazine (2a) and its 7-methoxy derivative (2b) by reductive cyclization, the dehydro forms of the naturally occurring cyclic hydroxamic acids DIBOA and DIMBOA from Gramineae.In contrast, hydrogenation of esters 1 in methanol results in the formation of amides 3 by acyl group migration.On heating, amides 3 undergo lactonization to form lactone-lactames 4, which in turn undergo ring opening to give amides 3 when refluxed in ethanol.
- Hartenstein, H.,Sicker, D.
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p. 359 - 362
(2007/10/02)
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- New synthesis of blepharin, the naturally occurring β-D-glucoside of 2-hydroxy-(2H, 4H)-1, 4-benzoxazin-3-one
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Blepharin, the β-D-glucoside (1) of 2-hydroxy (2H, 4H)-1, 4-benzoxazin-3-one(III), isolated from Blepharis edulis Pers., has been diaselectively synthesised from 2-hydroxy-(2H, 4H)-1, 4-benzoxazin-3-o-ne. The latter was obtained from isatin via a novel ring expansion reaction followed by glucosidation with 2,3,4,6-tetra-O-acetyl-β-D-glucopyranose and mild hydrolysis.
- Sahu,Chatterjee
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p. 603 - 605
(2007/10/02)
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- Benzoxazine-2,3-diones as Antiallergic Agents
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The synthesis of a series of benzoxazine-2,3-diones and a new class of compounds, benzobisoxazinetetrones, is described.These compounds were evaluated for their effect in the rat mast cell (RMC) test passively sensitized in vitro with rat antiovalbumin serum and for their effect in inhibitory passive cutaneous anaphylaxis (PCA) in the rat.Some of this compounds are of the same potency level as disodium cromglycate in the RMC test and some are effective orally in PCA.
- Loev, Bernard,Jones, Howard,Brown, Richard E.,Huang, Fu-chih,Khandawala, Atul,et. al.
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- Preparation of 2,3-dioxo-1,4-benzoxazine derivatives
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A process for the preparation of a 2,3-dioxo-1,4-benzoxazine derivative of the formula I STR1 where R1 and R2 are identical or different and each is hydrogen, alkyl, halogen, haloalkyl, alkoxy, haloalkoxy or nitro, by oxidizing an isatin of the formula II STR2 where R1 and R2 have the above meanings, with a peroxydisulfate dissolved or suspended in 30-98% strength sulfuric acid. The 2,3-dioxo-1,4-benzoxazine derivatives obtainable by the novel process have fungicidal or fungistatic properties.
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