2.3 -Dimethyl-1,4-dihydroxy benzene

The reaction mixture from acidified dihydroxyacetone also included a series of seven di- and tri-hydroxybenzenes (see Scheme 4), namely, 2,3-dihydroxytoluene (16), pyrocatechol (17), 3,4-dihydroxy toluene (19), 3,5-dimethyl-l,2-benzenediol (20), 1,2,3-trihydroxybenzene (pyrogallol) (21), 1,2,4-trihydroxy benzene (22), 3,4,5,6-tetrahydroxy-2-methy 1-acetophe-none, and 2,3-dihydroxy-5,6-dimethyl-p-benzoquinone. Many of these same phenolic compounds are present after hexoses are similarly treated... 

Firstly, the more hydroxylated compound, dihydroisopomiferin has been prepared as the dimethyl ether by a semi-synthetic route (ref. 89) from orobol dimethyl ether (5,7-dihydroxy-4 ,5 -dimethoxyisoflavone) by the drastic conditions of prenylation in benzene containing zinc chloride with prenylbromide. 

Reaction of the ArC,o unit with 1-pentynylmagnesium bromide occurred smoothly in tetrahyrofuran containing cuprous chloride without formation of alienic impurities. An analogous type of route was used for the synthesis of 1,3-dimethoxy-5-[(ZZ)-pentadec-8,11-dienyl]benzene, (15 2)-cardol dimethyl ether (ref. 105). For the synthesis of (15 2)-urushiol, 1,2-dihydroxy-3-[(ZZ)-penta-dec-8.11-dienyl]benzene and its dimethyl ether, 7-(2,3-dimethoxyphenyl)heptyl bromide and the corresponding 2,3-dihydroxy compound, obtained by demethylation with boron tribromide, have been used (ref. 149). 

The 5,6-dihydroxyindoles, including the parent system 1, are usually white-to-grey crystalline solids that melt with extensive decomposition and darkening. They are soluble in alcoholic solvents and acetone, less in acetonitrile, ethyl acetate, dimethyl sulphoxide (DMSO), tetrahydrofuran (THF), and water, and only sparingly soluble in hydrocarbons, e.g. benzene and light petroleum. A detailed physicochemical characterization of compound 1 was described by Murphy and Schultz (85JOC5873) (85JOC2790). The values for the first and second ionizations of indole 1 were determined as 8.9 and > 10.2, respectively. 5,6-Dihydroxy-1-methylindole 3 has values of 8.4 and 10.7 in water. 

A soln. of osmium tetroxide in dry benzene added at room temp, under Ng during 10 min. to a stirred soln. of 7,12-dimethylbenz [a] anthracene in dry benzene containing pyridine, allowed to stand 2 days, the benzene removed in vacuo, the residue dissolved in methylene chloride, then shaken 2 hrs. with 5 N NaOH and 1 M D-mannitol 5,6-dihydroxy-5,6-dihydro-7,12-dimethylbenz-[a]anthracene (Y 78%) dissolved in methanol-water, treated with Na-periodate in the same solvent mixture, and the product isolated after 2 days 1,4-dimethyl-2-phenylnaphthalene-3,2 -dicarboxaldehyde (startg. m. f. 206) (Y ca. 100%). H. I.Hadler and A. G. Kryger, J. Org. Ghem. 25, 1896 (1960). 

C5H8N2, Pyrazole, 3,5-dimethyl-, complexes with tungsten, 33 219 C6H8N2O2, Catechol, 4,5-diamino-, 33 112 C6HgBrN202, Benzene, l,2-dihydroxy-4,5-diamino-, hydrobromide, 33 115 C8H12N2O2, Benzene, l,2-dimethoxy-4,5-diamino-, 33 115... 

A mixture of 4-triphenylmethyl-l,2-benzoquinone, dimethyl phosphite, and dry benzene refluxed 2 hrs. dimethyl (5,6-dihydroxy- ,-a, -triphenyl-m-tolyl)phos-phonate. Y 90%. F. e., also reaction at oxygen with trialkyl phosphites, s. M. M. Sidky and F. H. Osman, Tetrahedron 29, 1725 (1973). 

Also obtained by partial methylation of 3,6-dihydroxy-2,4-dimethoxypropiophenone with dimethyl sulfate in the presence of potassium carbonate in refluxing benzene for 12 h [7542], (43%) [7405],... 

A soln. of 9,10-diketo-3,5-dimethoxy-1,4,4a, 9,9a, 10-hexahydroanthracene in 10-15 times the amount of anhydrous benzene added gradually with stirring at 5-7° to 5 moles ethereal methyl-magnesium iodide, and stirred without cooling for a further 3-5 hrs. 3,5-di-methoxy-9,10- dihydroxy -9,10- dimethyl-1,4,4a,9,9a, 10-hexahydroanthracene (Y 56%)... 

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