反应详情

A solution ob 304.4g. (2.0 mol) of trimethylhydroquinone in 1.2 liters of methanol and 300 ml. of trimethyl orthoformate was degassed, placed under N 2 and cooled in an ice bath to 3° centigrade. To the flask was added 5.0 ml. of concentrated aqueous sulfuric acid followed, dropwise over 3.0 hours, by 340 ml. (about 4.0 mol) of methyl vinyl ketone. The suspension was stirred without cooling for 44 hours. The mixture was worked up by extracting with diethyl ether, and washing with water, and saturated aqueous sodium bicarbonate and dried over sodium sulfate. The solvent was removed on a rotary evaporator at 30 to 50° centigrade to give (±)-6-hydroxy-2-methoxy-2,5,7,8-tetra-methylchroman as a light tan solid.

1. customof trimethyl orthoformate was degassed
2. temperaturecooled in an ice bath to 3° centigrade
3. additionTo the flask was added 5.0 ml
4. temperaturewithout cooling for 44 hours
5. extractionby extracting with diethyl ether
6. washwashing with water, and saturated aqueous sodium bicarbonate
7. dry with materialdried over sodium sulfate
8. customThe solvent was removed on a rotary evaporator at 30 to 50° centigrade