2,5-dimethylcyclohexa-2,5-diene-1,4-dione

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Under nitrogen atmosphere, 6 mL of THF was added to 1.22 g (2 mmol, 0.6 equivalent) of (BrZnCH2COOEt.THF)2. Under argon atmosphere, a solution of 0.45 g (3.33 mmol) of 2,5-dimethyl-p-benzoquinone in 3 mL of THF was added dropwise while stirring at. 0˜5° C. The mixture was stirred at 20˜25° C. for 1 hour. 5 mL of 1N hydrochloric acid was added dropwise at 20° C. or lower, followed by dilution with 25 mL of ethyl acetate. Then, the layers were separated. The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 5 mL (×2) of an aqueous saturated sodium bicarbonate solution, and 5 mL (×2) of an aqueous saturated sodium chloride solution. After washing, the organic layer was dried with anhydrous magnesium sulfate. After concentration under reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3, 1/2) afforded 0.65 g of the desired product (yield 87%). 0˜5° C The mixture was stirred at 20˜25° C. for 1 hour Then, the layers were separated The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 5 mL (×2) of an aqueous saturated sodium bicarbonate solution, and 5 mL (×2) of an aqueous saturated sodium chloride solution After washing the organic layer was dried with anhydrous magnesium sulfate After concentration under reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3, 1/2)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of 2,5-dimethyl-1,4-benzoquinone (68.1 g, 0.5 mol) in diethylether:THF (1:1, 800 ml) was added a solution of 80% sodium hydrosulfite (218 g, 1.0 mol) in water (800 ml) and the mixture was stirred for 30 minutes. The organic layer was separated, washed with saturated brine (800 ml), and then dried over anhydrous sodium sulfate. The organic layer was purified by silica gel chromatography with a small amount of silica gel and eluted with THF. The solvent was removed under reduced pressure to obtain 68.9 g as a yellow solid. The crystals were dissolved in ethanol (700 ml). To the solution were added dimethyl sulfate (189 ml, 2.0 mol) and 80% sodium hydrosulfite (21.8 g, 0.1 mol), and then added dropwise a 28% solution of sodium methoxide in methanol (482 ml, 2.5 mol) under reflux. After completion of the addition, the mixture was further stirred under reflux for 3 hours and then the solvent was removed under reduced pressure. The residue was poured into ice-cold water (2000 ml) and extracted with ethyl acetate. The organic layer was separated, washed with saturated brine and dried over magnesium sulfate, and then the solvent was removed under reduced pressure. The residue was purified by silica gel chromatography with a small amount of silica gel and eluted with ethyl acetate:hexane (1:4), and the solvent was removed under reduced pressure. The organic layer was separated washed with saturated brine (800 ml) dried over anhydrous sodium sulfate The organic layer was purified by silica gel chromatography with a small amount of silica gel eluted with THF The solvent was removed under reduced pressure to obtain 68.9 g as a yellow solid under reflux After completion of the addition the mixture was further stirred under reflux for 3 hours the solvent was removed under reduced pressure The residue was poured into ice-cold water (2000 ml) extracted with ethyl acetate The organic layer was separated washed with saturated brine dried over magnesium sulfate the solvent was removed under reduced pressure The residue was purified by silica gel chromatography with a small amount of silica gel eluted with ethyl acetate:hexane (1:4) the solvent was removed under reduced pressure

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Under nitrogen atmosphere, 6 mL of THF was added to 1.22 g (2 mmol, 0.6 equivalent) of (BrZnCH2COOEt.THF)2. Under argon atmosphere, a solution of 0.45 g (3.33 mmol) of 2,5-dimethyl-p-benzoquinone in 3 mL of THF was added dropwise while stirring at. 0˜5° C. The mixture was stirred at 20˜25° C. for 1 hour. 5 mL of 1N hydrochloric acid was added dropwise at 20° C. or lower, followed by dilution with 25 mL of ethyl acetate. Then, the layers were separated. The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 5 mL (×2) of an aqueous saturated sodium bicarbonate solution, and 5 mL (×2) of an aqueous saturated sodium chloride solution. After washing, the organic layer was dried with anhydrous magnesium sulfate. After concentration under reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3, 1/2) afforded 0.65 g of the desired product (yield 87%). 0˜5° C The mixture was stirred at 20˜25° C. for 1 hour Then, the layers were separated The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 5 mL (×2) of an aqueous saturated sodium bicarbonate solution, and 5 mL (×2) of an aqueous saturated sodium chloride solution After washing the organic layer was dried with anhydrous magnesium sulfate After concentration under reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3, 1/2)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Under nitrogen atmosphere, 6 mL of THF was added to 1.22 g (2 mmol, 0.6 equivalent) of (BrZnCH2COOEt.THF)2. Under argon atmosphere, a solution of 0.45 g (3.33 mmol) of 2,5-dimethyl-p-benzoquinone in 3 mL of THF was added dropwise while stirring at. 0˜5° C. The mixture was stirred at 20˜25° C. for 1 hour. 5 mL of 1N hydrochloric acid was added dropwise at 20° C. or lower, followed by dilution with 25 mL of ethyl acetate. Then, the layers were separated. The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 5 mL (×2) of an aqueous saturated sodium bicarbonate solution, and 5 mL (×2) of an aqueous saturated sodium chloride solution. After washing, the organic layer was dried with anhydrous magnesium sulfate. After concentration under reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3, 1/2) afforded 0.65 g of the desired product (yield 87%). 0˜5° C The mixture was stirred at 20˜25° C. for 1 hour Then, the layers were separated The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 5 mL (×2) of an aqueous saturated sodium bicarbonate solution, and 5 mL (×2) of an aqueous saturated sodium chloride solution After washing the organic layer was dried with anhydrous magnesium sulfate After concentration under reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3, 1/2)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To 2.24 g of thiourea were added 60 ml of ethanol and 2.5 ml of concentrated hydrochloric acid, followed by stirring. Then a solution of 8.0 g of p-xyloquinone in ethanol (120 ml) was slowly added dropwise thereto. The reaction mixture was stirred at room temperature for 24 hours and then concentrated to about one-half. The crystals thus precipitated were separated by filtering and washed with a small amount of ethanol. Thus 6.80 g of the title compound was obtained in the form of white crystals. The reaction mixture was stirred at room temperature for 24 hours concentrated to about one-half The crystals thus precipitated were separated by filtering washed with a small amount of ethanol

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To 2.24 g of thiourea were added 60 ml of ethanol and 2.5 ml of concentrated hydrochloric acid, followed by stirring. Then a solution of 8.0 g of p-xyloquinone in ethanol (120 ml) was slowly added dropwise thereto. The reaction mixture was stirred at room temperature for 24 hours and then concentrated to about one-half. The crystals thus precipitated were separated by filtering and washed with a small amount of ethanol. Thus 6.80 g of the title compound was obtained in the form of white crystals. The reaction mixture was stirred at room temperature for 24 hours concentrated to about one-half The crystals thus precipitated were separated by filtering washed with a small amount of ethanol

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2,5-Dimethylbenzoquinone (5 g) in ethyl acetate was shaken with an aqueous solution of sodium hydrosulfite. The organic layer was separated, washed, dried and evaporated to yield 2,5-dimethylhydroquinone. To a solution of 2,5-dimethylhydroquinone (5 g), prepared as described above, and 3-methyl-2-buten-1-ol (3.1 g) in dioxane (20 mL) was added BF3-ether (4.5 mL) at room temperature under nitrogen. The solution was stirred at room temperature for one hour, extracted with ethyl acetate, washed with water and dried. The mixture containing starting material and alkylated product was hydrogenated in methanol (100 mL) with 5 drops of concentrated HCl in the presence of Pd/C (10%, 200 mg) at60 psi for 18 hours. Workup and chromatography (silica gel hexane-ethyl acetate 5% to 12%) gave 2 g of the desired product, 2,5-dimethyl-3-(3-methyl-butyl)-hydroquinone. The organic layer was separated washed dried evaporated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Under nitrogen atmosphere, 6 mL of THF was added to 1.22 g (2 mmol, 0.6 equivalent) of (BrZnCH2COOEt.THF)2. Under argon atmosphere, a solution of 0.45 g (3.33 mmol) of 2,5-dimethyl-p-benzoquinone in 3 mL of THF was added dropwise while stirring at. 0˜5° C. The mixture was stirred at 20˜25° C. for 1 hour. 5 mL of 1N hydrochloric acid was added dropwise at 20° C. or lower, followed by dilution with 25 mL of ethyl acetate. Then, the layers were separated. The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 5 mL (×2) of an aqueous saturated sodium bicarbonate solution, and 5 mL (×2) of an aqueous saturated sodium chloride solution. After washing, the organic layer was dried with anhydrous magnesium sulfate. After concentration under reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3, 1/2) afforded 0.65 g of the desired product (yield 87%). 0˜5° C The mixture was stirred at 20˜25° C. for 1 hour Then, the layers were separated The organic layer was washed successively with 5 mL (×2) of 1N hydrochloric acid, 5 mL of water, 5 mL (×2) of an aqueous saturated sodium bicarbonate solution, and 5 mL (×2) of an aqueous saturated sodium chloride solution After washing the organic layer was dried with anhydrous magnesium sulfate After concentration under reduced pressure, purification with silica gel column (developing solvent; ethyl acetate/n-hexane=1/3, 1/2)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2,5-Dimethylbenzoquinone (10 g, 73.5 mmol) was dissolved in 300 mL of ether, which was mixed with an aqueous solution of sodium hydrosulfite (178 g in 150 mL of water, 85% pure, 870 mmol). The mixture was shaken until the ether layer became nearly colorless. The ether layer was separated, and the aqueous layer was extracted with ethyl ether (3×200 mL). The combined ether layers were washed with brine (2×150 mL) and dried over MgSO4. Filtration and solvent evaporation gave 10.03 g (72.6 mmol) of the hydroquinone as a white solid. The ether layer was separated the aqueous layer was extracted with ethyl ether (3×200 mL) The combined ether layers were washed with brine (2×150 mL) dried over MgSO4 Filtration and solvent evaporation

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 12.2 g of 2,5-dimethylphenol (0.1 mole), 1.98 g of cobalt di-(3-methylsalcylal)-3,3'-diimino-di-n-propylamine (0.0005 mole) and 0.5 g of N-methylpiperidine were dissolved in 200 ml of chloroform and then air was bubbled through the resulting solution at 15°C for 10 hours during which time the reaction was completed. After completion of the reaction, the reaction mixture was rendered basic by adding a 2% aqueous solution of sodium hydroxide to decompose peroxides present in the mixture followed by addition of dilute hydrochloric acid to render the solution acidic. The resulting solution was extracted with ether which was then distilled off to obtain 12.1 g of 2,5-dimethyl-parabenzoquinone (0.09 mole). air was bubbled through the resulting solution at 15°C for 10 hours during which time the reaction After completion of the reaction The resulting solution was extracted with ether which was then distilled off