3- Methoxy-o-benzoquinone

Most compounds were studied as liquids or solids, depending on their state at ambient conditions. However, a few that were either available in very small quantities or difficult to study were analyzed in solutions. Others were studied both as solids and in solution to determine if any changes occurred in their spectral features upon dissolution. Coniferaldehyde and trans-ferulic acid (samples 17 and 18, respectively) were studied as solids and in solution in methanol. 3-methoxy-o-benzoquinone and 2-methoxy-p-benzoquinone (samples 23 and 24) were studied as solutions in benzene. 

It has been suggested that quinones are present in milled wood lignins [30]. However, their occurrence in wood and pulps is doubtful. The quinone models studied, 3-methoxy-o-benzoquinone (sample 23) and 2-methoxy-p-benzoquinone (sample 24), did not show any Raman bands when studied using 514.5-nm laser excitation. These compounds were fluorescent and degraded in the laser beam. Nevertheless, such structures, if present, are not expected to survive various bleaching treatments. Quinones are easily attacked chemically and probably do not survive peroxide and borohydride bleaching [19, 31, 32]. 

Reagents for the syntheses were obtained from Aldrich Chemical Co. (organic) and MCB (CUCI2 2H2O). The six bis(9-aminoacridine) compounds were supplied by the Drug Synthesis and Chemistry Branch, Division of Cancer Treatment, National Cancer Institute. 3-Methoxy-o-benzoquinone was prepared by a published method , m.p. 114-116 C, reported 107-110 C27. 

To test the viability of 5a involvement in redox processes, we performed cyclic voltammetry on a model, namely, 3-methoxy-o-benzoquinone,... 

Table 1. Cyclic Voltammetry of 3-methoxy o-benzoquinone (5b) and Cu Dips .

An electron transfer mechanism is advanced for various classes of anticancer agents. The neoplasm is presumably destroyed by induction of oxidative stress. Cyclic voltammetry was performed on some of the main categories quinones (3-methoxy-o-benzoquinone, etoposide model), metal complexes [Cu(II)(3,5-diisopropylsalicylate)2] (Cu Dips) and iminium from bis(9-aminoacridines). Reduction potentials ranged from +0.28 to -0.88 V. Electrochemical behavior is related to structure and physiological activity. 

Diels-Alder reactions. Unhke p-benzoquinones, which are potent dieno-philes in Diels-Alder reactions, o-benzoquinones can function as either dienes or dienophiles. Danishefsky et al. reasoned that 4-methoxy-o-benzoquinones should serve predominantly as dienophiles. Indeed when heated in a sealed tube at 105° for 5 hr. with 1,3-butadiene, the quinone (1) gives (3) in 63% yield. This product is evidently formed by cycloaddition to the 5,6-double bond followed by enolization to the diosphenol. 

Alkaline hydrolysis of benzal acetone structures to the corresponding aldehyde (XIX) and acetone and subsequent oxidation of the aldehyde (XIX) to the corresponding benzoic acid (V) do not seem to represent an actual degradation stage since oxidizing the aldehyde (XIX) under our mild standard conditions yielded only traces of the corresponding benzoic acid (V). The aldehyde (XIX) was rapidly decomposed via Dakin reaction to formic acid and 3-methoxy-S-methyl-o-benzoquinone, which is immediately degraded to phenolic humic compounds. 

DIELS-ALDER REACTIONS Benzocyclopropene. 1,2-BisC3-tosyIethoxycarbonyl)-diazene. Cyclobutadiene iron tricarbonyl. 1,2-Dicyanocyclobutene. Diethyl ketomalonate. 1,3,4,6-Heptatetraene. 2-Hydroxy-5-oxo-5,6-dihydro-2/f-pyrone. 3-Hydroxy-2-pyrone. Isopropylidene isopropylidenemalonate. Lithium tetra-methylpiperidide. 4-Methoxy-5-acetoxymethyl-o-benzoquinone. 4-Methoxy-5-methyl-o-benzoquinone. frans-l-Methoxy-3-trimethyl-silyloxy-l,3-butadiene. Per-fluorotetramethylcyclopentadiene. 4-Phenyl-l, 2,4-triazoline-3,5-dione. Potassium f-butoxide. 

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)... 

AT-Formylnor-reticuline, on treatment with 2,3-dichloro-5,6-dicyano-l,4-benzoquinone in methanol, is oxidized to the 4-methoxy-compound (35), which can be cyclized to N-norbisnorargemonine (36) (converted by N- and O-methylation into argemonine) by mineral acid or to the isopavine N-formyl-northalidine (37) by treatment with methanesulphonic acid in acetonitrile. The N-formyl compounds can be reduced to AT-methyl by borane or converted into the secondary bases by hydrazinolysis.69... 

The regioselective nudeophUic attack of the arylamine at the 2-methoxy-substituted iron complex salt is controlled by the methoxy group, which directs the arylamine to the para-position. Moreover, electrophilic attack takes place at the sterically less-hindered orfho-amino position. Iron-mediated oxidative cyclization of the resulting iron complex to the carbazole followed by proton-catalyzed aimulation of the furan ring provides 8-methoxyfurostifoline. Oxidation with 2,3-dich]oro-5,6-dicyano-l,4-benzoquinone (DDQ) to O-methylfurodausine-A followed by deavage of the methyl ether provides furoclausine-A (five steps, 9 % overall yidd). 

Treatment of an (allyloxymethyl)cyclopropane derivative with butyllithium also resulted in alkylation accompanied by C-O bond cleavage,but other products predominated to a considerable extent, rendering the method synthetically useless. Another and more successful rearrangement took place on refluxing 4-(l-cyclopropylalkoxy)-5-methoxy-l,2-benzoquinones in acetic acid to give 3-alkyl-2-hydroxy-5-methoxy-l,4-benzoquinone in 25-40% yield. 

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