was charged boc 2 o 26 0 g 0 119 mol the reaction mixture was gradually warmed to 35 40 u00b0 c and aged at 35 40 u00b0 c for additional 14 hours the batch was cooled to ambient temperature and an aqueous solution of 7 5 wt nahco 3 50 ml the separated organic layer was solvent switched to heptane at final volume of u02dc 300 ml in vacuum while the internal temperature was maintained at 35 45 u00b0 c the resulting slurry was aged 2 hours at 20 u00b0 c before filtration the wet cake was washed with heptane 100 ml and vacuum oven dried at 40 u00b0 c to give 18 3g of the product compound i 2 1 h nmr 400 mhz cdcl 3 u03b4 5 09 s br 1h 4 74 s br 1h 2 43 m 2h 2 08 t j 2 8 hz 1h 2 04 m 2h 1 47 s 9h 13 c nmr 100 mhz cdcl 3 u03b4 154 4 118 5 81 4 70 9 41 8 32 1 28 4 15 1 the separated organic phase was concentrated to u02dc 50 ml in vacuum which was then added to a slurry of heptane 375 ml seeded with product 125 mg over several hours at 15 25 u00b0 c the batch was then solvent switched to heptane in vacuum at final volume of 250 ml maintaining.