An efficient formal synthesis of the human telomerase inhibitor (±)-γ-rubromycin

Abstract

Balancing act: The correct balance of electronic factors in the naphthazarin and isocoumarin fragments facilitates the acid-mediated spiroketalization step to afford the key densely functionalized spiroketal (see picture; EOM=ethoxymethyl) in the formal synthesis of (±)-γ- rubromycin. A novel regioselective allyloxylation/Claisen rearrangement of 2-azido-1,4-naphthoquinone provides access to the highly oxygenated naphthazarin fragment. © 2009 Wiley-VCH Verlag.