Synthesis of 3-arylisocoumarins, including thunberginols A and B, unsummetrical 3,4-disubstituted isocoumarins, and 3-ylidenephthalides via iodolactonization of methyl 2-ynylbenzoates or the corresponding carboxylic acids

3-Aryl-4-iodoisocoumarins, which were readily and efficiently prepd. by regioselective iodolactonization of Me 2-ynylbenzoates or the corresponding carboxylic acids, were used as precursors either to 3-arylisocoumarins, including naturally-occurring thunberginols A and B, or to unsym. 3,4-disubstituted isocoumarins. On the other hand, (Z)- and (E)-3-iodomethylidenephthalides, which were regioselectively prepd. by iodolactonization of Me 2-ethynylbenzoate, were employed as starting materials for the stereospecific synthesis of (Z)- and (E)-3-ylidenephthalides, resp. Some 3-arylisocoumarins and unsym. 3,4-disubstituted isocoumarins showed certain cytotoxic activity against human cancer cell lines in vitro.