The PL-100 compound (product of step F, 203 mg, 0.325 mmol) was dissolved in dry tetrahydrofuran (3 mL) and 0.2 mL triethylphosphate under N2 atmosphere. The mixture was stirred at this temperature for 15 min, followed by the addition of diethyl chlorophosphate (0.061 mL, 0.423 mmol). Sodium hydride (60% in mineral oil) (17 mg, 0.423 mmol) was added at 0° C. The solution was stirred for 1 h at 0° C. and 12 h at room temperature. 20 mL of Amberlite XAD-2 was added to the solution and the beads were thoroughly mixed with the solvent. To the mixture was added ice water 2 mL, and the THF evaporated off. The beads were then washed with distilled water 6 times 100 mL then extracted three times with ethyl acetate (30 mL). The combined phase was evaporated and the residue was dried under high vacuum. The crude product was purified by flash chromatography using ethyl acetate/hexane (8/2), then EtOAc 100% as eluent. The yield of this reaction is 152 mg 61%.
