1 1 g 79 hplc tr 0 405 min ymc s5 combiscreen ods 4 6 u00d7 50 mm 10 90 aqueous methanol containing 0 2 h 3 po 4 4 min gradient monitored at 254 nm 1 h nmr 400 mhz dmso d 6 u03b4 10 4 s 1h 8 13 br s 2h 7 31 br s 1h 7 10 br s 1h 6 88 t 1h j 2 0 hz 6 75 dd 1h j 1 6 4 0 hz 6 05 t 1h j 3 6 hz a solution of 1b 1 1 g 6 0 mmol in 1n naoh 35 9 ml 35 9 mmol was treated with cu oac 2 u2014 h 2 o 1 3 g 6 8 mmol and heated to 85 u00b0 c for 90 minutes the resulting suspension was cooled to ambient temperature and filtered through a pad of celite the celite pad was washed with 1n naoh 10 ml and the filtrate was collected the clear filtrate was treated with glacial acetic acid until ph 6 was reached and the resulting suspension was cooled to 0 u00b0 c for one hour the precipitated product was collected via vacuum filtration and dried under high vacuum to afford 1c 780 mg 87 hplc tr 1 228 min ymc s5 combiscreen ods 4 6 u00d7 50 mm 10 90 aqueous methanol containing 0 2 h 3 po 4 4 min gradient monitored at 254 nm 1 h nmr 400 mhz dmso d 6 u03b4 10 6 s 1h 7 22 t 1h j 2 0 hz 6 69 dd 1h j 1 2 4 0 hz 6 30 dd 1h j 2 4 4 4 hz.