1 427 mg 1 05 mmol in ethyl acetate was washed with 5 potassium bisulfate three times water and brine dried over sodium sulfate filtered concentrated stripped with dichloromethane twice and dried in vacuo overnight to give the free acid as a crystalline solid the free acid was dissolved in anhydrous dichtoromethane 4 ml cooled to 0 u00b0 c in an ice bath and treated with triethylamine 134 u03bcl 0 96 mmol then compound a 237 mg 0 88 mmol in anhydrous dichloromethane 5 ml and finally bop reagent 465 mg 1 05 mmol the resultant solution was stirred at 0 u00b0 c for 1 hour and then at room temperature for 4 hours the reaction mixture was concentrated diluted with ethyl acetate 75 ml washed with 5 potassium bisulfate 40 ml saturated sodium bicarbonate solution 40 ml 50 brine 40 ml and brine 40 ml dried over sodium sulfate filtered and evaporated to dryness the crude product 462 mg was absorbed onto celite u00ae and chromatographed on a silica gel column 5 u00d7 10 cm eluting with 30 2 l ethyl acetate hexane the desired fractions were combined and concentrated affording 368 mg 87 from compound h from example 1 of pure compound b tlc r f 0 49 silica gel 1 1 ethyl acetate hexane uv and pma detection a solution of compound b 469.