Carbon Dioxide → Benzopyran

Participants

Reaction Steps

In 50 cc of anhydrous ether was dissolved 3.06 g (0.01 mole) of the chromanone compound obtained in Example 32, represented by the following formula: ##STR163## and the solution was cooled to 0° C. and Grignard reagent CH3MgI (0.012 mole) 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 quietly poured into cold water to extract the product with ether. The ether extract was dried on magnesium sulfate to form a chromanol compound from the chromanone compound. Then, the chromanol compound was heated at 200° C. together with anhydrous copper sulfate in a carbon dioxide current for about 10 minutes. The obtained brown viscous liquid was purified by the chromatography on silica gel to obtain 2.47 g of a chromene compound represented by the following formula: ##STR164##

Provenance & Evidence