To a solution of the compound prepared in Example 323 (555 mg) in dichloromethane (7.0 mL) at 0° C. was added diisopropylethylamine (0.59 mL) followed by methyl 2-chloro-2-oxoacetate (0.16 mL). The reaction was allowed to warm to room temperature and then stirred for 2 hours. The solution was diluted with ethyl acetate, washed with saturated aqueous sodium bicarbonate solution and brine. The organics were dried over magnesium sulfate, filtered and concentrated under reduced pressure to afford the crude material, which was purified by flash column chromatography (eluant: 80% ethyl acetate/hexane with 3% (9:1 methanol/concentrated ammonium hydroxide)) to furnish the title compound (392 mg) with the following physical properties.
