3,4-Benzoquinones 1-amino

The chlorination of the antibacterial sulfonamide sulfamethoxazole was initiated by N-chlorination of the primary amine. Further reaction of the A,A-dichlorinated compound resulted in the final production of 3-amino-5-methyloxazole and 1,4-benzoquinone-imine (Dodd and Huang 2004). 

I, 4-benzoquinone.4 Other methods that have been employed include the oxidation of naphthalene with hydrogen peroxide,5 the oxidation of 1,4-naphthalenediamine 6 and naphthylamine sulfonic acid 7 and the oxidation of 4-amino-1-naphthol prepared by electrolytic reduction of 1-nitronaphthalene.8... 

A simple spectrophotmetric method for the determination of niclosamide in bulk and dosage forms was developed [44]. It was based on the reduction of the nitro group in niclosamide to the amino group by treatment with zinc powder and dilute HC1 for 15 min in 95% ethanol solution. The cold and clear filtrate reacted with p-benzoquinone, when a pink compound was obtained which absorbed at 506 nm. 

Gong and co-workers employed an intermolecular Nenitzescu reaction, a type lice transformation, for the condensation of a P-amino-a,(3-unsaturated ester with 1,4-benzoquinone to afford a 5-hydroxyindole derivative <06BMC911>. 

Both 3-amino-N-ethylcarbazole and l,4-diethoxy-2-amino-5-benzoylamino-benzene are suitable aromatic amines. Chloranil may also be replaced by 2,5-di-chloro-3,6-bisacetylamino-l,4-benzoquinone to react with appropriately substituted o-alkoxyanilines. 

An excess of tetrachloro-p-benzoquinone (chloranil) in o-dichlorobenzene is added to 2 moles of 3-amino-N-ethylcarbazol and dry sodium acetate, which acts as an acid trap. The mixture is stirred for 6 hours at 60°C, then within 5 hours heated to 115°C under vacuum, after which benzenesulfochloride is added at the same temperature. Cyclization is achieved by increasing the temperature to 175-180°C. The reaction mixture is agitated until no more acetic acid appears in the distillation receiver (for 4 to 8 hours). The reaction product is vacuum filtered, residual o-dichlorobenzene removed by steam distillation, the product washed, and dried. A patent which was issued in 1980 claims a much improved yield if the reaction is performed in the presence of only a slight excess of chloranil, provided 0.15 to 1.8 wt% water is added to the reaction mixture [5],... 

In continuation to our studies in area the preparation and investigation of bioactive benzoquinones [2-4] we report in this work the preparation and evaluation of algicidal activity of abenquines and new analogues. With this aim, variations were introduced in their scaffold by either replacing the amino acid substituent with different amines, or adding a bulky group through the substitution of the acetyl for a... 

Addition of 7-amino-2,2-dimethylchromene 107 to 2-methyl-1,4-benzoquinone 108 in acetic acid/water leads to the 2-arylamino-5-methyl-1,4-benzoquinone 109 in moderate yield (Scheme 34). Oxidative cyclization of compound 109 using a stoichiometric amount of palladium(II) acetate in acetic acid under reflux provides pyrayaquinone A 110 [42,132]. 

The antibacterial agent sulfamethoxazole produced chlorinated and nonchlorinated DBFs when reacted with chlorine [91]. A ring-chlorinated product was formed via halogenation of the aniline moiety at sub-stoichiometiic concentrations of chlorine. 3-Amino-5-methylisoxazole, sulfate, and A-chloro-p-benzoquinone imine were formed via rupture of the sulfamethoxazole sulfonamide moiety at stoichiometric excess of chlorine. 

Benzoquinone reacted with dialkyl aminocrotonate to give 3-amino-4-carbalkoxy-6-hydroxycoumarin (90J HCl 447). 

The H-NMR spectra were recorded at different temperatures to determine the ring-chain equilibrium constants in solutions of 2-N- 2-hydroxyethyl)amino-5-methyl-l,4-benzoquinones 33 (93M1053). Greater... 

Xhe synthesis of thieno[3,2-c]benzazepine-l,6-dione by treatment of 3-methyl-amino-3-methylthio-l -phenylthioxopropene with 2-hydroxy-l, 4-benzoquinone, which serves as enolizable cyclic ketone, has been reported (2000JOC3690). 

Wu et al. reported the total synthesis of clausenaquinone A (112) using a palladium(ll)-mediated oxidative cyclization of the 2-arylamino-5-methoxy-l,4-benzoquinone 874 (107). This total synthesis was undertaken to establish the structure of natural clausenaquinone A (112). The key intermediate, 2-(3-hydroxy-4-methylanilino)-5-methoxy-l,4-benzoquinone (874), required for this synthesis, was obtained by the reaction of 5-amino-o-cresol (873) with 2-methoxy-l,4-benzoquinone (872) which was readily obtained by oxidation of methoxyhydroquinone (871). The palladium(ll)-mediated oxidative cyclization is non-regioselective. Thus, the cyclization of the 2-arylamino-5-methoxy-l,4-benzoquinone 874 with palladium(Il)... 

Routes to benzoxadiazoles are based on approaches to the tautomeric 6-diazo-2,4-cyclo-hexadienones (Scheme 11) <9UST(247)135>. The appropriate 2-aminophenol hydrochloride is diazo-tized using either sodium nitrite or isoamyl nitrite and the diazonium chloride is then carefully neutralized with sodium carbonate or potassium carbonate. An alternative approach is from the monotosylhydrazone of the appropriate o-benzoquinone. Naphthoxadiazole (6) was prepared, in a manner analogous to the first route of Scheme 11, from 3-amino-2-naphthol <91AG(E)1476>. A slightly modified preparation is described in a later paper the method was applied to the synthesis of [9a- C]naphth[2,3-( ]-l,2,3-oxadiazole from 3-amino-[2- C]-2-naphthol <92Mi 403-03>. 

Microwave heating was found to improve yields of this process <2004SC315>. A one-pot reaction was also reported where the cyclization was accompanied by introduction of a new cyclic amino substituent on the aromatic ring (Equation 32) <2005S1876>. A similar but metal-catalyzed cycloaddition of a 1,2-benzoquinone monoxime 300 with dimethyl acetylenedicarboxylate (DMAD) gives both 301 and 302 (Equation 33) <1995JCM454, 1995JRM2701>. 

Intramolecular aminopalladation has been applied to the total synthesis of the complex skeleton of bukittinggine (179). For this reaction. Pd(CF3CO )2 (10 mol%) and benzoquinone (1.1 equiv.) are used. It is important to use freshly recrystallized benzoquinone for successful cyclization. Formation of a 7r-allylpalladium species as an intermediate in this amination reaction has been suggested 182]. The amino group in obromoaniline reacts first with acrylate in the presence of PdCF to give 180, and then intramolecular Heck reaction of the resulting alkene 180 with Pd(0) catalyst affords indolecarboxylate 181[183]. 

Nitro-2,5-dihydroxy-l,4 benzoquinone, CgHaNOg mw 185.09, N 7.57% golden-yel ndls, mp-not reported mod sol in w was prepared by warming 1 part of 3 nitro-2-hydroxy-5-amino-1,4-benzoquinone-l-imide with 10-15 pts of 10% KOH (Refs 1 2)... 

To our knowledge, the first examples of asymmetrically substituted monocyclic phosphoranes are 60 and 61, described by Moriarty et al.135 and involving the reaction of a substituted o-benzoquinone136,137 (Scheme 6) on an aminophosphine (59), itself obtained by alcoholysis of 58 with l-( — )-menthol. In contrast to the amino phosphine 53 (Scheme 5), 59 is a mixture of the diastereoisomers 59a and b, and its reaction with 3,5-di-tert-butyl-l,2-benzoquinone yields two diastereoisomeric phosphoranes, 60a and b. Finally, alcoholysis of the P(V)—NR2 bond138 in 60a and b leads to 61a and b or 62. 

Benzophenone, 2-amino, 32, 8 THIO-, 35, 97 Benzopyrazole, 39, 27 -Benzoquinone, 35, 26 Benzoylacetanilide, 37, 2 Benzoylacetic acid, ethyl ester,... 

The red products obtained from the interaction of tyrosine and either o- or p-benzoquinone described by Bouchilloux 285 are probably 4-amino-o-quinone and 3-amino-p-quinone derivatives, respectively. 

Lau and Gompf359 prepared a series of 2-amino-6-hydroxybenzo[d]-thiazoles and corresponding naphtho[l,2-d]thiazoles on treating 1,4-benzoquinone and 1,4-naphthoquinone with thiourea in acidic media at room temperature. At high temperature the products of the reaction with 1,4-benzoquinone are 5-hydroxy benz[d]-l,3-oxathiol-2-ones... 

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