Three dihydrocoumarins and one benzodipyran have been prepared via reactions of phloroglucinol with acrylic acids or substituted ones catalyzed by strongly acidic ion-exchange resin, of which the 5-hydroxy-3,4,6,7-tetrahydrobenzo[1,2-b;5,4-b']dipyran-2,8-dione and 3,4-dihydro-5,7-dihydroxy-3-methylcoumarin are the firstly reported compounds. Itwas found that the substituted acrylic acids were less reactive than the acrylicacids, and the yields of 2a rised from 20%to 66% when the mixed solvent tulene-THF was used in place of single solvent toluene.

Key words: acidic ion-exchange resin, phloroglucinol, dihydrocoumarins, benzodipyrans, synthesis