Carbon Dioxide → Benzopyran

Participants

Reaction Steps

A solution was prepared by dissolving 10 g (0.054 mole) of 1-hydroxy-2-acetonaphthone, 6.6 g (0.06 mole) of norcamphor and 8 g (0.113 mole) of pyrrolidine in 300 cc of toluene. The solution was boiled for 10 hours and water was separated. After termination of the reaction, toluene was removed under reduced pressure, and the remaining chromanone compound was crystallized with acetone. Then, the chromanone compound was dissolved in 200 cc of methanol, and sodium boron hydride was gradually added to the solution to form a chromanol compound. Then, 7.47 g of the chromanol compound was heated at 150° C. to 160° C. together with 4.5 g of anhydrous copper sulfate in a carbon dioxide current for 10 minutes and the obtained viscous liquid was purified by the chromatography on silica gel to obtain 6.3 g of a chromene compound of the following formula: ##STR70##

Provenance & Evidence