Naphthoquinone 2-amino

Synonyms 2-Chloro-3-amino-1,4-naphthoquinone 1,4-Naphthoquinone, 2-amino-3-chloro Quinoclamine... 

Spray solution For amino acids Dissolve 0.2-0.3 g l -naphthoquinone-4< sulfonic acid sodium salt in 100 ml aqueous sodium carbonate solution (5-10%) [1]. 

The shikimate pathway is the major route in the biosynthesis of ubiquinone, menaquinone, phyloquinone, plastoquinone, and various colored naphthoquinones. The early steps of this process are common with the steps involved in the biosynthesis of phenols, flavonoids, and aromatic amino acids. Shikimic acid is formed in several steps from precursors of carbohydrate metabolism. The key intermediate in quinone biosynthesis via the shikimate pathway is the chorismate. In the case of ubiquinones, the chorismate is converted to para-hydoxybenzoate and then, depending on the organism, the process continues with prenylation, decarboxylation, three hydroxy-lations, and three methylation steps. - ... 

Vela, M., Saurina, J., and Hemandez-Cassou, S., Flow-injection spectrophoto-metric determination of amino acids by using l,2,-naphthoquinone-4-sul-fonate immobilized on an ion exchange resin, Anal. Lett., 31, 313, 1998. 

Abou-Ouf et al. [16] described a spectrophotometric method for the determination of primaquine phosphate in pharmaceutical preparation. Two color reactions for the analysis of primaquine phosphate dosage form, which are based on 2,6-dichlor-oquinone chlorimide and l,2-naphthoquinone-4-sulfonate, were described. The reactions depend on the presence of active centers in the primaquine molecule. These are the hydrogen atoms at position 5 of the quinoline nucleus and the primary amino group of the side chain. The method was applied to tablets of primaquine phosphate and a combination of primaquine phosphate and amodiaquine hydrochloride. 

An alternative reagent which also reacts with the primary amino groups of neomycin has recently been describedl72. The reagent, diclone(2,3-dichloro-l, 4-naphthoquinone), reacts with neomycin base to form an orange-coloured product when the solution is adjusted to pH 4. 

The reaction of 5-amino-37/-l,3,4-thiadiazole-2-thione 452 with 2,3-dichloro-l,4-naphthoquinone 453 in DMF, at room temperature (rt) for 48 h, gave the complex naphthoquinoimidazolothiadiazole 454 (Equation 104) <1996PS(116)261>. 

Amino-1,4- and 4-amino-1,2-naphthoquinones (74 and 75) failed to react with EMME, probably because of the amide-like character of the amino group. However, their 2,3- and 3,4-dihydro derivatives (76 and 77)... 

Amino-substituted naphthoquinones and heterocyclic variants have been disclosed in the patent literature as 5-LO inhibitors. Compounds represented by (80) (X = C, N) from Lilly inhibited SRS-A release from sensitized guinea-pig lung tissue [218]. Similar compounds such as (81) (R = carboxylic ester, acyl, or aryl) and related naphthalene derivatives, from American Cyanamid, gave good inhibition in guinea-pig ISN (at 10 //g/ml) and in passive cutaneous anaphylaxis in mice (25-60 /zM i.p.) [219,220]. 

Condensed derivatives are also known. Treatment of 2-amino-l,3,4-thiadiazoles with 2,3-dichloro-l,4-naphthoquinone or 6-chloroquinoline-5,8-dione yields 102 and 103, respectively (82H333, 91JIC529). 

Amino-l,4-naphthoquinone 492 was reacted as a bidentate nucleophile in condensations with acetals 493 to form m-2,4 disubstituted-l,4-dihydro-27f-naphth[2,3-,7 [l,3]oxazine-5,10-diones 494 stereoselectively by 6-endo-trig-nng closure of the N,C-dialkylated intermediates (Equation 56) <1995T6565>. 

When 2-amino-l,4-naphthoquinone 492 was reacted with aliphatic aldehydes in the presence of a catalytic amount of TEA, the opposite diastereoselectivity of the reaction was reported. Except for the unsubstituted compound (R = H), the product proved to be a mixture of the diastereomers of l,4-dihydro-2//-naphth[2,3-rf [l,3]oxazine-5,10-diones in which the /ra r-isomer 495 was the predominant component (Equation 57). A slight tendency could be observed for increasing bulkiness of the substituent R to favor a higher proportion of the m-isomer 494 in the diastereomeric mixture <2003MI51>. 

The second method is that described above /3-naphthol is converted through the nitroso derivative and i-amino-2-naph-thol-4-sulfonic acid into naphthoquinone sulfonate, and this is subjected to acid hydrolysis. The sulfonate can be converted directly into hydroxynaphthoquinone by the action of concentrated sulfuric acid,3,4 but the process is not so easily controlled as when the quinone is etherified as it is formed, and the ether subsequently hydrolyzed.4 The overall yield from /3-naphthol is 46 per cent of the theoretical amount, but all the reagents are inexpensive, and with ordinary apparatus, 150 g. of hydroxynaphthoquinone can be made conveniently in one run (from 300 g. of /3-naphthol). 

If technical i-amino-2-naphthol-4-sulfonic acid is used, the yield of ammonium i,2-naphthoquinone-4-sulfonate is 313 g. (84 per cent) of a rust-colored product. If the technical material... 

Salts of 1,2-naphthoquinone-4-sulfonate have been prepared by the oxidation of 2-amino-i-naphthol-4-sulfonic acid with nitric acid,2 or by the oxidation of the more readily available i-amino-2-naphthol-4-sulfonic acid with the same reagent.3,4 5... 

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... 

Phenoxazin-3-ones and phenothiazin-3-ones can be prepared by the oxidation of the parent heterocycles in acidic media, but it is often more practical to employ condensation reactions between 2-amino-phenols or -thiols and quinones. Alizarin Green G (263), for example, is obtained from the aminophenol (261) and the 1,2-naphthoquinone (262). Similarly, 2-aminothiophenols (264) and 6-chloro-2-methoxy-l,4-benzoquinone (265) afford phenothiazin-3-ones (266) bearing methoxyl groups at position 1. 

Mechanisms of competing reactions of Wittig reagents with substituted 2-amino- 1,4-naphthoquinones have been discussed73 and a study of the stereoselectivity of the indirect Wittig reaction of a 1,2-hydroxyphosphonium salt has led to the conclusion... 

Bcnzofuran-4,7-dioncs have been synthesized regioselectively by [3 + 2] photoaddition of 2-hydroxy-1,4-benzoquinones with a range of alkenes (equation 185)664. The reaction occurs in 30-60% yield and is a useful method for the synthesis of the benzofuran ring system, which is important in natural products like acamelin665. Substituted naphthoquinones may also be used in this reaction666,667 and this has lead to a very simple two-step synthesis of maturinone. In a similar reaction, a [3 + 2] photoaddition reaction of 2-amino-1,4-naphthoquinones with electron-rich alkenes gave 13-82% yields of 2,3-dihydro-177-bcn/ /]indole-4,9-diones in a single-step process which involved photolysis followed by oxidation (equation 186)668,669. 

Condensation of 5-(arylethynyl)-3-(diethylamino)naphthoquinones 64 with hydrazine afforded 3-benzyl-9-(diethyl-amino)bcnzo[zA ]cinnolin-7-oncs 66. Replacement of the arylethynyl substituent in the starting naphthaquinone by a 3-hydroxyalk-l-ynyl group leads to a change in the direction of cyclization, resulting in substituted naphtha[l,8-zv/ -l,2-diazepin-8-ones 65, as condensation products <2001RCB1668> (Scheme 13). 

Note. (1) For the reduction of Orange II to l-amino-2-naphthol and its conversion to 1,2-naphthoquinone, see Expt 6.131. 

Diels-Alder reactions of a,fi-unsaturatedN,N-dimethylhydrazones.1 These readily available hydrazones can function as 1-amino-l-aza-l,3-dienes in Diels-Alder reactions. Thus, 1 undergoes regioselective cycloaddition with various electrophilic dienophiles to give tetrahydropyridines such as 2 and 3. Unfortunately, removal of the dimethylamino group with zinc and acetic acid (or other reagents) also effects reduction of the double bond. The initial adduct from cycloaddition of 1 with naphthoquinone is unstable and undergoes spontaneous elimination of the elements of dimethylamine to give the aromatic adduct 4. 

Hydroxylated 1,4-benzoquinones and 1,4-naphthoquinones gave similarly the corresponding dipoles [164]. The amino analogs reacted in the same way to afford first isolable iodonium salts and then the imino dipoles (Scheme 54) [165]. It is noted that the open-chain methyl 2-aminocrotonate gave with [hydroxy(tosyloxy)iodo]benzene only the iodonium salt, i.e. -MeC(NH2) = C(COOMe)I+Ph TsO- [166]. 

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