To a 0° C. solution of 0.10 g of the product of Example 3 (0.30 mmols) in DMF (1.0 mL) was added 0.041 mL of triethylamine (0.30 mmols) and 0.056 g of 4-methoxybenzoylchloride (0.33 mmols). The reaction mixture was allowed to warm to rt and stirred for 23 h. The reaction mixture was diluted with 1 mL of water and 5 mL of EtOAc. The layers were separated, and the aqueous layer was extracted with EtOAc. The combined organics were washed with water and concentrated to a partial volume. Methanol was added, and a solid precipitated from the solution. The precipitate was filtered off and dried and the crude product was purified by silica gel chromatography to provide the title compound as a white powder (0.029 g, 21%). MS (ES+) m/e 473 [M+H]+.
