Purification by flash column chromatography, eluting with 1-4% 7N methanolic ammonia solution in dichloromethane afforded a pale brown solid. This solid was dissolved in acetic acid and heated to reflux for 2 hours, after which the reaction mixture was cooled, concentrated under reduced pressure, and successively reconcentrated from ethyl acetate (100 mL) and then heptane (3 x 300 mL). The residue was dissolved in ethyl acetate (300 mL) and poured into saturated aqueous sodium hydrogen carbonate solution (400 mL). The organic phase was collected and washed with brine (500 mL), dried over anhydrous magnesium sulfate and concentrated under reduced pressure. Purification by flash column chromatography, eluting with 3-7% 7N methanolic ammonia solution in dichloromethane afforded a beige solid. This solid was dissolved in