Regiospecific synthesis of 3-(2,6-dihydroxyphenyl)phthalides: application to the synthesis of isopestacin and cryphonectric acid

DBU catalyzed condensation of phthalaldehydic acids and 1,3-diketones has been developed to be a general method for the synthesis of 3-substituted phthalides. This method, in combination with mercuric acetate mediated oxidative aromatization has been utilized for the regiospecific synthesis of isopestacin (9) and cryphonectric acid (10).