2-Hydroxy-1,4-naphthoquinon

Furoquinones, such as naphtho[2,3-b]fiiran-4,9-dione, naphtho[l,2-b]fiiran-4,5-dione, benzofuran-4,7-dione and benzofiiran-4,5-dione derivatives are available by the ceric ammonium nitrate mediated [3+2] cycloaddition of 2-hydroxy-1,4-naphthoquinones and 2-hydroxy-1,4-benzoquinones with alkenes or phenylacetylene <96CL451>. 

Photolytic. Based on data for phenol, a structurally related compound, an aqueous solution containing 1-naphthoxide ion (3 x 10 M) in room light would be expected to photooxidize to give 2-hydroxy-1,4-naphthoquinone (Tomkiewicz et al., 1971). 1-Naphthol, methyl isocyanate, and other unidentified cholinesterase inhibitors were reported as products formed from the direct photolysis of carbaryl by sunlight (Wolfe et al., 1976). In an aqueous solution at 25 °C, the photolysis half-life of carbaryl by natural sunlight or UV light (X = 313 nm) is 6.6 d (Wolfe et al, 1978a). 

When these cycloaddition reactions are carried out with alkynes, furan derivatives are formed. lodonium ylide 5, for instance, on photochemical reaction with alkynes 43, gives benzofurans 44 (86JOC3453) (Eq. 19). In a similar way, the iodonium ylide derived from 2-hydroxy-1,4-naphthoquinone undergoes a cycloaddition reaction with phenylacety-lene to yield benzofuran 45 (Scheme 16) (89LA167). 

Lawsone (Cl Natural Orange 6 Cl 75420), also known as henna and isojuglonc. occurs in the shrub henna [Lawsone alba). Lawsone has been identified as 2-hydroxy-1.4-naphthoquinone. It has been synthesized by the Thiele acetylation of 1.4-naphthoquinnne followed by hydrolysis and oxidation. 

Benzimidoyl-2-hydroxy-1, 4-naphthoquinone Heteroaromatic anticancer agents erythro-9-(2-hydroxy-3-nonyl)adenine, 3-deazauridine and thioquanine Tolbutamide Nifedipine... 

Acylated indoles, in their enol form (54), are formed by heating the phenyliodo-nium ylide of 2-hydroxy-1,4-naphthoquinone in the presence of some indoles.58 The intermediacy of an o ,a ,-dioxoketene (55) is suggested. The same reactants (with the exception of indole itself) form 3-(3-indolyl)-2-hydroxy-1,4-naphthoquinones in a Cu(II)-catalysed reaction. 

Mn(OAc)3-promoted oxidative reaction of 2-hydroxy-1,4-naphthoquinone (280) with a p-enamino carbonyl compound generates a spiro-lactam (281) as shown in eq. 3.115. 

A synthesis of lapachol using reaction conditions better than those used by Fieser was carried out by Fridman et al [149].They used the lithium salt of 2-hydroxy-1,4-naphthoquinone prepared in situ instead of the silver salt used for Fieser [150]. The lithium salt was prepared in situ by addition of lithium hydride to the frozen solution of the quinone in dimethyl sulfoxide, Fig. (14). As the solution thawed, the lithium quinone was slowly formed and was then alkylated with 3,3-dimethylallyl bromide. Lapachol was thus obtained in 40% yield. 

The a- and p-tetralones are also oxidized to 2-hydroxy-1,4-naphthoquinone by KO, and a crown ether in 75% yield. In the absence of a crown ether, the oxidation proceeds slowly and in low yield (—10%). The a- and p naphthols are intermediates. ... 

There are only a few synthetic approaches toward these polycyclic systems. The coupling product from diazotized anthranilic acid and 2-hydroxy-1,4-naphthoquinone is transformed into 372 by heating with acetic anhydride (83IJC(B)95). The same quinone reacts with citral and, depending on the reaction conditions, several products are formed. In a triethylamine-catalyzed reaction, the angular quinones 373 and 374 are formed, whereas acid-catalyzed condensation gives the linear compound 375 (82SC195 ... 

Atovaguone, USP.. 3- 4-(4-Chlorophenyl)-cyclohexyl -2-hydroxy-1.4-naphthoquinone (Mepron) is a highly lipophilic, water-insoluble analogue of ubiquinone 6. an es.sen-tial componcni of the mitochondrial electron transport chain in micmorganism.s. The. structural similarity between atovaquone and ubiquinone suggests that the former may act as an antimctabolilc for the latter and thereby interfere with the function of electron transport en/ymes. 

Diaeyl peroxides, R( oO( r. Preparation (a) RCOCl -F NajOzl (b) RCOCI + H2O2 + NaOH. Use for alkylation of 2-hydroxy-1,4-naphthoquinone. The reaction... 

Fieser " found that alkylation of the silver salt of 2-hydroxy-1,4-naphthoquinone with methyl iodide in ether or benzene gives a mixture of about equal parts of the para and ortho quinone piethyl ethers and that the mixture is easily separated by treatment with sodium bisulfite solution. The para quinone dissolves to a negligible... 

Pyrazolo[3,4-Z)]pyridines, the 7-chloro-6-fluoro-2,4-dimethylquinoline and its mercapto-thiadiazolyl or oxadiazolyl quinolines 21 were prepared via Diels-Alder reaction conversion of methyl 2-(3-oxo-3-phenylpropenylamino)benzoate into 3-benzoyl-l.S -quinolin-4-one 22 . A mixture of aniline derivatives and malonic ester gave a variety of 3-aryl-4-hydroxyquinolin-2(l//)-ones 23. Condensation of isatins with ketones afforded quinoline-4-carboxylic acids. 2-Aryl-l,2,3,4-tetrahydro-4-quinolinones 22 and carbazolylquinolone were also prepared. The substitution of 2-chloroquinoline gave the 2-substituted quinolines. Basic alumina has catalyzed the C-C bond formation between 2-hydroxy-1,4-naphthoquinone and 2-chloroquinoline derivative to give 21. Reaction of organic halides with 8-hydroxyquinolines gave the respective ethers. The azodye derivatives of 21 were prepared in the absence of solvent. Silica gel catalyzed the formation of 2-ketomethylquinolines from reaction of 2-methylquinolines with acyl chlorides. 

A variety of heterocyclic compounds of the indole and benzofuran type can be made via photoaddition of alkenes to 2-amino- or 2-hydroxy-1,4-naphthoquinone. These products, described by H. Suginome probably derive from an intramolecular trapping reaction of the intermediary 1,4-biradicals or 1,4-zwitterions. 

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