Quinoxalin-2-ones nitro

Reaction of o-phenylenediamine and n-butyl glyoxylate gives quinoxalin-2-onc in excellent yield with 4-nitro-o-phcnylcncdiaminc (5) a mixture of 6- and 7-nitro-quinoxaIin-2-ones, (6) and (7), is obtained. ... 

Quinoxalin-2-ones, unlike quinoxaline itself, may be nitrated under mild conditions. Nitration of quinoxalin-2-one in acetic acid gives mainly the 7-nitro derivative in sulfuric acid, the 6-nitro compound is formed (Scheme 6). ... 

Brightener structures of only moderate molecular size are of interest for white grounds in the transfer printing of polyester fabrics. Derivatives of 6-acetamidoquinoxaline with an electron-donating substituent (X) in the 2-position (11.48) were prepared by converting quinoxalin-2-one to 2-chloro-6-nitroquinoxaline and condensation with amines (X = RNH), alcohols (X = RO) or phenols (X = PhO), followed by reduction and acetylation (Scheme 11.19). The nitro intermediates (11.49) are also of interest as low-energy disperse dyes for polyester [61]. 

Our approach was based on the observation that it is possible to perform SwAr reactions on solid support with amino acids using a solvent system comprised, in equal parts, of acetone and an aqueous 0.5 M NaHC03 solution at temperatures around 70-75°C. Application of this solvent system to the synthesis of quinoxalin-2-ones 6 from la and a-amino acids is described in Section 3.3.2. With respect to the synthesis of 1,5-ben-zodiazepin-2-ones 4, more than 40 examples of aliphatic and aromatic P-amino acids 35 were found to furnish the desired o-nitro anilines 36, about 80% of which were successfully carried on to eventually afford the ben-zodiazepinone products 4 (Scheme 6). In general, the anthranilic acids required slightly harsher conditions to drive the fluorine displacement to completion (75-80°C, 72 h vs. 70-75°C, 24 h for aliphatic P-amino acids). 

The regiospecific oxidative nitration of 3,4-dihydro-6,7-disubstituted quinoxalin-2(l//)-ones utilizing fuming nitric acid in trifluoroacetic acid gives 5-nitro-6,7-disubstituted quinoxa-line-2,3(l/f,4/f)-diones in good yields. 

The nitration of quinoxaline presumably involves the conjugate acid formed by addition of a proton to one of the nitrogen atoms.Direct nitration of quinoxaline under forcing conditions using concentrated nitric acid and oleum gives a mixture of 5-nitro- and 5,6-dini-troquinoxaline in 1.5% and 24% yield, respectively. - The formation of a mixture of... 

The benzene ring of quinoxalin-2(177)-ones is activated towards electrophilic substitution, and nitration results in the formation of the 7-nitro derivative when the reaction is carried out in acetic acid solution in concentrated sulfuric acid, where the base is present in a protonated form, the 6-nitro compound is formed. - ... 

Nitration of quinoxaline-2,3(l//,4//)-dione proceeds at the 6- and 7-positions, e.g. nitration with one or two equivalents of potassium nitrate in concentrated sulfuric acid yields the 6-nitro and 6,7-dinitro compounds, respectively. Nitration of 8-(carbamoy methy )su fonyl-benzo[/]quinoxaline-2,3(17/,4//)-dione with potassium nitrate in concentrated sulfuric acid gives the 6-nitro derivative in 52% yield. 

An example of exchange with an oxygen-containing functional group is given which utilises a micellar system. Cationic micelles of cetyltrimethylammonium chloride and bromide, and tetradecyltrimethylammonium chloride and bromide, accelerate the reaction of 2-(4-nitro-phenoxy)quinoxaline with hydroxide ion to give quinoxalin-2(l/f)-one. ... 

Peracetic acid treatment of l,2-dihydro-l-methyl-2-oxoquinoxaline (11) gives the 3-oxygenated derivative (13), and similar treatment of 1,2-dihydro-l,3-dimethyl-2-oxoquinoxaline gives a small quantity of the 4-oxide. Both compoimd 11 and its 6-nitro derivative %2 are converted in high yield to the corresponding quinoxalin-3-ones 13 and 14 on treatment with aqueous hydrogen peroxide in acetic acid at room tempera-... 

Electrophilic substitution of quinoxaline-2,3-dione and its 1,4-dimethyl derivative occxu at positions 6 and 7. For example, treatment of a solution of quinoxaline-2,3-dione in concentrated sulfuric acid with one equivalent of potassium nitrate yields the 6-nitro derivative, whereas with two equivalents of potassium nitrate 6,7-dinitroquinoxaline-2,3-dione is formed. 6-Bromo and 6,7-dibromoquinoxaline-2,3-dione have been prepared by bromination of the 2,3-dione in sulfuric acid with bromine and silver sulfate, and chlorination is found to occur under similar conditions. Treatment of quinoxaline-2,3-dione with fuming sulfuric acid yields the... 

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