反应详情

A mixture of 20 ml of water, 5.2 g (30 millimole) of dibromo-methane and 0.5 g (1 millimole) of Adogen 464 (Aldrich) is heated to boiling under vigorous stirring. A solution of 4.2 g (20 millimoles) of 6,7-dihydroxy-2,2-dimethyl-4-chromanone and 50 ml of a 5% sodium hydroxide solution is added dropwise within 2 hours and heated to boiling for a further hour. The mixture is diluted with 100 ml of water and extracted twice with 50 ml of chloroform each. The organic layer is washed twice with 50 ml of water, dried over sodium sulfate, the solvent is removed and the residue crystallized from hexane. Thus 3.6 g of the desired compound are obtained, yield 85%. Mp: 61°-62° C.

1. temperatureis heated
2. temperatureheated
3. waitto boiling for a further hour
4. extractionextracted twice with 50 ml of chloroform each
5. washThe organic layer is washed twice with 50 ml of water
6. dry with materialdried over sodium sulfate
7. customthe solvent is removed
8. customthe residue crystallized from hexane