Abstract
The condensation of homophthalic acid 6 with the appropriate acid chlorides 7a-c yield the respective isocoumarins 8a-c, which are converted to keto-acids 9a-c by alkaline hydrolysis. The 3,4-dihydroisocoumarins 12a-c are obtained by reduction of the keto-acids 9a-c to hydroxy-acids 11a-c followed by cyclodehydration using acetic anhydride.