Benzylamine → 11-(4S)-{2-[(benzylaminomethyl)-dimethylsilanyl]-ethyl}-4-ethyl-4-hydroxy-1,12-dihydro-4H-2-oxa-6,12a-diaza-dibenzo[b,h]fluorene-3,13-dione

A solution of Compound 3 (100 mg) and benzylamine (70 μL) in acetonitrile (2 mL) was heated at 110° C. over 8 hours. Solvent was removed under reduced pressure and the crude product was stirred in trifluoroacetic acid (1 mL) for 2 hours at room temperature. Finally, trifluoroacetic acid was removed under reduced pressure and the crude product was partitioned between chloroform (20 mL) and 7% aqueous NaHCO3 solution (10 mL). The chloroform layer was dried and concentrated and purified on a silica gel column using 4% ethanol in dichloromethane to obtain the product in 50% yield (57 mg).