On the basis of the information obtained from our previous studies on relationship between structure and sweet taste of 3, 4-dihydroisocoumarins, 5-hydroxyflavanones and related dihydrochalcones were synthesized. Compounds (2, 3, 4, and 7) had a sweet taste while the others were tasteless. The relationship of structure-sweet taste of 5-hydroxy-flavanones was similar to that of 3, 4-dihydroisocoumarins.