Carbon Dioxide → Benzopyran

Participants

Reaction Steps

In 50 cc of anhydrous ether was dissolved 2.78 g (0.01 mole) of the chromanone compound obtained in Example 2, represented by the following formula: ##STR72## and the solution was cooled to 0° C. and 0.012 mole of Grignard reagent CH3MgI newly prepared in 50 cc of anhydrous ether was dropped into the solution over a period of about 1 hour. After termination of the dropwise addition, the mixture was stirred at room temperature for 2 hours and was gradually poured into cold water to extract the product with ether. The ether extract was dried on magnesium sulfate and ether was removed under reduced pressure to form a chromanol compound from the chromanon compound. Then, the obtained chromanol compound was heated at 200° C. together with anhydrous copper sulfate in a carbon dioxide current for about 10 minutes, and the obtained brown viscous liquid was purified by the chromatography on silica gel to obtain 2.24 g of a chromene compound represented by the following formula: ##STR73##

Provenance & Evidence