8-Hydroxy-l,4-naphthoquinone

Hydrolysis and photolysis of carbaryl forms 1-naphthol (Wauchope and Haque, 1973 Rajagopal et al., 1984, 1986 Miles et al., 1988 MacRae, 1989 Ramanand et al., 1988a Lewis, 1989 Somasundaram et al, 1991) and 2-hydroxy-l,4-naphthoquinone (Wauchope and Haque, 1973), respectively. In aqueous solutions, carbaryl hydrolyzes to 1-naphthol (Boethling and Alexander, 1979 Vontor et al., 1972), methylamine, and carbon dioxide (Vontor et al., 1972), especially under alkaline conditions (Wolfe et al., 1978). At pH values of 5, 7, and 9, the hydrolysis half-lives at 27 °C were 1,500,15, and 0.15 d, respectively (Wolfe et al., 1978). 

Compounds of type LXXIII cannot be made by the rearrangement of the 7-substituted allyl ethers, because these compounds yield LXXIV by inversion. a,7-Dimethylallyl bromide,16 7,7-dimethylallyl bromide,29 cinnamyl chloride,84 and phytyl bromide 86 (a vitamin K synthesis) have been used in C-alkylation procedures. The silver salt of 2-hydroxy-l,4-naphthoquinone is converted to a mixture of C-alkylation product and two isomeric ethers by treatment with allylic halides and benzyl halides. ... 

The Williamson synthesis, using a sodium phenoxide and allyl bromide in methanol solution, is more rapid than the procedure using acetone and potassium carbonate and gives good results.16-36 441 66 Aqueous acetone also has been used as the reaction medium with allyl bromide and sodium hydroxide this method likewise is rapid and sometimes leads to better yields than the procedure using potassium carbonate and acetone.34 Allylation of 2-hydroxy-l,4-naphthoquinone has been carried out by treating the silver salt, in benzene, with allyl bromide 84 some C-alkylation as well as O-alkylation was observed. 

Methylallyloxy)-l, 4-naphtho-quinone 0.5 140 — 3-(a-Methylallyl)-2-hydroxy-l,4- naphthoquinone >85% 126... 

Quinoline derivatives (60) have been synthesized by the reaction of 5-alkyl-l,3,4-thia-diazol/oxadiazol-2-thiols with 7-chloro-6-uoro-2,4-dimethylquinoline and by the reaction of 2-hydroxy-l,4-naphthoquinone with 2-chloro-3-formyl-4-methyl/ 6-methyl/7-methyl/8-methylquinolines, respectively, on basic alumina using micro-waves (Kidwai et al., 2000). 

Thermal decomposition of phenyliodonium ylide of 2-hydroxy-l,4-naphthoquinone (lawsone) 403 in the presence of indole derivatives 402 (GH2CI2, reflux, 4-7 h) affords 3-acylated indoles existing in their enol forms 404, through a ring contraction and ot,ot -dioxoketene formation reaction (Scheme 87) <2005JOC8780>. 

The same reactants afford 3-(3-indolyl)-2-hydroxy-l,4-naphthoquinones 405 in a copper-catalyzed reaction (CH2CI2, 00(0+3803)2, rt, overnight). In case the more electron-rich position 3 in the indole ring is substituted, as in 3-methylindole, the reaction takes place from position 2, but the yield of the corresponding derivative is very low (7%) (Equation 95). The thermal reaction of reagent 403 with 1-methylpyrrole afforded the expected acylation product 407 in high yield (Equation 96) <2005J008780>. 

Diacyl peroxides are good agents for the alkylation of p-benzo- and 1,4-naphthoquinones having a free position in the quinoid ring, particularly when the normal- or iso-alkyl chains are desired (3( 60%). The method has been widely applied in the synthesis of 2-hydroxy-l,4-naphthoquinones substituted in the 3-position. The procedure consists in adding slowly a solution of the diacyl peroxide in ether to a solution of the quinone in acetic acid at 90-95°. 

Thiele reaction Boron trifluoride etherate. Perchloric acid (see 2-Hydroxy-l,4-naphthoquinone). 

Natural cinchona alkaloids were recently examined as catalysts for Michael addition reactions. In the presence of a natural cinchona alkaloid such as cinchonine (CN), 2-hydroxy-l,4-naphthoquinone 168 as the nucleophilic component was added... 

Hydroxy-l,4-naphthoquinone (Lawsone B, Neutral Orange 6, tautomeric with 4-hydroxy-... 

Hydroxy-l,4-naphthoquinone, 4-hydroxy-6-methylpyrone, and a-naphthol can be used instead of 116 to afford the corresponding condensation products in good to excellent yields. 

Hydroxy-l,4-naphthoquinone/shaken with ether and hydrosulfite... 

Gokhale et al. [72] have synthesized a series of hydroxynaphthoquinone metal complexes as antitumor agents. The cytotoxic studies against the human breast cancer cell line MCF-7 revealed enhanced activities for the metal complexes. The highest activity is observed for the copper compound of lawsone, Fig. (12) (2-hydroxy-l,4-naphthoquinone). 

Although many of the products of the reaction were very polar, as shown by HPLC and thin-layer chromatography, we were able to determine some of the products by extracting the aqueous solution of a preparative-scale reaction done at pH 8 with diethyl ether and analyzing the extract by gas chromatography-mass spectroscopy (GC-MS). The principal ether-soluble product was 2-hydroxy-l,4-naphthoquinone (lawsone, 4). The mass spectrum of lawsone was sufficiently characteristic to distinguish it clearly from other hydroxynaphthoquinone isomers such as Juglone (11). Lawsone has also been reported previously as a product of photolysis of 1-naphthol in alkaline solution (12). 

Kirkland, D., and D. Marzin. 2003. An assessment of the genotox-icity of 2-hydroxy-l,4-naphthoquinone, the natural dye ingredient of henna. Mutat. Res. 537(2) 183-199. 

Khurana and his group developed a catalyst-free synthesis of novel benzo [a] [l,3]oxazino[6,5-c]phenazine derivatives via a one-pot four-component domino protocol, consisting of 2-hydroxy-l, 4-naphthoquinone, o-phenyl-enediamine, aliphatic or aromatic amines, and formaldehyde, and using water as the solvent (Scheme 50) (14TL6652).The products were obtained in good-to-high yields. 

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