Synthesis of Pyranonaphthoquinone Antibiotics Involving the Phthalide Annulation Strategy

The synthesis of the pyranonaphthoquinone antibiotic pentalongin was performed using the phthalide annulation strategy. Annulation of the cyanophthalide onto 6Hpyran-3-one resulted in a hongconin analogue, which upon further elaboration was converted into the natural product.