Synthesis of Some New Dihalophenyl- and Dihalobenzylisocoumarins and Their (dl)-3,4-Dihydroderivatives

摘要

3-Dihalophenyl- and dihalobenzylisocoumarins (3a-c) were synthesized by condensation of homoph-thalic acid (1) with dihalobenzoyl- and dihalophenylacetyl chlorides (2a-c),respectively.The alkaline hydrolysis of these isocoumarins (2a-c) afforded keto-acids (4a-c).(dl)-3-(Dihalophenyl)- and (dl)-3-(dihalobenzyl)-3,4-dihydroisocoumarins (6a-c) were obtained by reduction of keto-acids (4a-c) to racemic hydroxy-acids (5a-c) followed by cyclodehydration using acetic anhydride.