Phosphoric Acid → (+/-)-2-p-Tolylchroman-4-one

Participants

Reaction Steps

The 2'-Hydroxy-4-methylchalcone of Example 13 (7.3 g.) was boiled under reflux with a solution of 85% phosphoric acid (22 ml.) in 2-methoxyethanol (219 ml.) for 8 hrs. The reaction mixture was diluted with water (1 liter) and the oily precipitate extracted into dichloromethane (300 ml.). The organic extract was separated and washed with water and saturated sodium bicarbonate solution. Filtration and evaporation gave a residue of 4'-methylflavanone contaminated with the starting chalcone.

Provenance & Evidence