6 93 mmol are added and stirred at 25 u00b0 c for 5 h the solvent is removed 10 ml water is then added and the aqueous layer is extracted with etoac the crude mixture is then subjected to column chromatography on silica gel using hexane dcm mixtures to afford the product 10a as a viscous liquid 1 25 g in 69 yield 1 h nmr 200 mhz cdcl 3 u03b4 7 40 7 34 m 5h 6 97 6 83 m 2h 6 58 bs 1h 5 17 s 2h 3 26 t j 6 19 hz 4h 0 85 t j 6 19 hz 4h 0 09 s 6h 13 c nmr 50 mhz cdcl 3 u03b4 159 04 dd j 246 9 hz 9 4 hz 153 24 135 83 133 56 t j 13 5 hz 128 66 128 47 128 35 126 36 t j 14 6 hz 102 79 d j 29 5 hz 67 24 51 88 15 54 u2212 2 94 to a solution of 10a 1 10 g 2 81 mmol and s tert butyl 3 chloro 2 hydroxypropylcarbamate 1 06 g 5 06 mmol in dmf 10 ml lio t bu 675 mg 8 43 mmol is added at 0 u00b0 c the mixture is stirred at 25 u00b0 c for.