An Efficient Formal Synthesis of the Human Telomerase Inhibitor (±)-γ-Rubromycin†

(1, Scheme 1), the prototypical member of astructurally related family of antibiotics known as therubromycins, consists of a densely oxygenated naphthazarinring and an isocoumarin moiety linked through a uniquearomatic 5,6-spiroketal ring system (Scheme 1). The rubro-mycins exhibit a wide range of biological activity includingantimicrobialandanticancerproperties.