the solvent was removed by evaporation under vacuum the residue was partitioned between saturated sodium bicarbonate solution and dichloromethane the aqueous layer was extracted with dichloromethane the combined organic layers were washed with brine and dried over sodium sulfate evaporation of the solvent under vacuum provided crude 4 4 4 fluorophenoxy benzenesulfonylamino tetrahydropyran 4 carboxylic acid ethyl ester as an amber oil 21 05 grams flash chromatography on silica gel eluting with 25 ethyl acetate hexane followed by 50 ethyl acetate hexane provided 4 4 4 fluorophenoxy benzenesulfonylamino tetrahydropyran 4 carboxylic acid ethyl ester as an off white crystalline solid 12 15 grams 71 mp 116 117 u00b0 c 1 hnmr cdcl 3 u03b4 7 79 d 2h 7 09 t 2h 7 02 m 2h 6 97 d 2h 5 10 s 1h 4 01 q 2h 3 60 m 4h 2 08 m 2h 1 84 br d 2h 1 23 t 3h m s atmospheric pressure chemical ionization mass spectra 424 m 1 a solution of 4 4 4 fluorophenoxy benzenesulfonylamino tetrahydropyran 4 carboxylic acid ethyl ester 12 1 grams 0 0286 mole in tetrahydrofuran 190 ml was treated with aqueous 3 m sodium hydroxide solution 95 ml 0 286 mole and stirred at room temperature for 4 days the solvent was evaporated under vacuum and the residue partitioned between water and diethyl ether the aqueous layer was washed with diethyl ether acidified to ph 1 with 3n aqueous hydrochloric acid solution and extracted with dichloromethane after washing with water the organic extract was.