Novel "reverse Kahne-type glycosylation": access to O-, N-, and C-linked epipodophyllotoxin conjugates

[formula: see text] Exposure of epipodophyllotoxin C4-sulfoxides to triflic anhydride, followed by a silyl glycoside, provides a glycoconjugate of the etoposide variety via formal "reverse Kahne glycosylation." To our knowledge, this is the first example of this variant of the Kahne activation method wherein the activating functionality is positioned on the aglycon, rather than on the sugar. Phenols, anilines, or allyl silanes are also efficiently captured at C4, producing the corresponding O-, N-, and C-linked lignan conjugates.