Total Synthesis of AGI-7 and Sescandelin from Enol Esters

摘要

A silver salt-mediated aerobic approach to access 4-acetyl 3- unsubstituted isocoumarins from the reaction of ortho-iodobenzoic acid and enol ester in the presence of a base has been presented. The reaction proceeds through the base mediated initial cleavage of the enol ester followed silver-mediated Carylation reaction. Intramolecular annulation of the resulting intermediate followed by dehydration produces the 4-acyl isocoumarins. Selective demethylation of the 4-acylated isocoumarin affords biologically potent AGI-7, while selective reduction followed by demethylation enabled the sescandelin in good yield.