To a suspension of the product of Example 27 Step B (195 mg) in N,N-dimethylformamide (2 mL) was added triethylamine (0.12 mL) and the mixture cooled to 0° C. 3-chloropropanesulfonyl chloride (0.11 mL) was added dropwise and the mixture stirred for 1.5 hours before the addition of H2O (2 mL). The reaction mixture was partitioned between H2O (15 mL) and ethyl acetate (15 mL). The aqueous layer was brought to pH=9–10 with saturated sodium bicarbonate solution and extracted with ethyl acetate (2×). The combined organic layers were dried over magnesium sulfate, decanted, and evaporated. The residue was purified via silica gel chromatography (dichloromethane/methanol) to give the title compound (210 mg).
