反应详情

In 28 ml of ethanol was dissolved 1.82 g (10 mmol.) of 2,3-dimethoxy-5-methyl-1,4-benzoquinone. To the solution was portionwise added at room temperature 240 mg (6.3 mmol.) of sodium borohydride. The mixture was stirred for 15 min. The mixture was then made acidic by addition of 3-N hydrochloric acid. To the mixture were added 50 ml of water and 100 ml of ether for performing extraction. The ether portion waswashed with water and a saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, and placed under reduced pressure to distill off the solvent to give 1.72 g of 2,3-dimethoxy-5-methylhydroquinone as a yellow oil, yield 93.5%. To the resulting oil were added 1.65 g (9.3 mmol.) of methyl 1-piperazinecarbodithioate and 280 mg (9.3 mmol.) of paraformaldehyde. Themixture was added to 17 ml of chloroform, and the resulting mixture was refluxed under heating for 6 hours. To the heated mixture was added water.The aqueous mixture was then extracted with chloroform. The chloroform extract was washed with water and a saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, and placed under reduced pressure to distill off the solvent. The residue was dissolved in 10 ml ofethanol. Insolubles were removed by filtration. The filtrate was placed under reduced pressure to distill off ethanol. The residue was then purified by means of silica gel column, to give 1.1 g of a pale yellow oil, yield 31.8%. The oil was crystallized from ethanol. The crystals werecollected by filtration to give 790 mg of the desired compound as a yellow crystalline proudct, m.p. 135°-136° C.

1. extractionextraction
2. dry with materiala saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate
3. distillationto distill off the solvent