Syntheses of differentially protected isocoumarins

Syntheses of an isocoumarin subunit suitable for the completion of purpuromycin are outlined. Specifically, work targeting an orthogonally protected isocoumarin (eventually 12% yield over 12 steps) and an improved synthesis of a symmetrically protected isocoumarin (18% over 10 steps) are described. A new modification for selective catechol protection as mediated by potassium bicarbonate is also presented along with insights into oxidative and reductive functionalization of isocoumarins.