To a stirred solution of dimethyl methylphosphonate (1.9 mL, 17.08 mmol) in THF (20 mL) at −78° C. was added nBuLi (10.94 mL, 17.5 mmol). After 30 minutes, 4-9 (1 g , 4.27 mmol) in THF (5 mL) was added. After 1 hour, the reaction was quenched with saturated NH4Cl (10 mL) and warmed to ambient temperature. The mixture was diluted with ethyl acetate, washed with sat. NaHCO3, brine, and dried over MgSO4. Following evaporative removal of the solvent, the residue was chromatographed (silica gel, 70/25/5 CHCl3/EtOAc/MeOH) to give 4-10 as a yellow oil.
