Efficient reversed-phase purification of a hydrophobic reaction product following Mitsunobu-mediated glycosylation

The Mitsunobu reaction was used to attach tetra-O-benzyl-d-glucopyranose to a monoindolylmaleimide, providing a key intermediate in the total synthesis of indolocarbazole topoisomerase I poisons. Using normal-phase silica gel chromatography, purification of the glycosylated product normally required multiple columns, resulting in poor recovered yields. Reversed-phase chromatography was used successfully to purify this highly hydrophobic material, rapidly and in high yield.