under reduced pressure to a residue 3 63 g chromatography on 350 g of silica gel packed with acetone and methylene chloride 3 97 and eluted with 3 5 acetone in methylene chloride yields pure 16 phenoxy 17 18 19 20 tetranor pge 2 methyl ester 11 15 bis tetrahydropyranyl ether 2 8 g silica gel tlc r f is 0 5 in acetone and methylene chloride 1 19 c under a nitrogen atmosphere with exclusion of moisture 2 52 g of methylphenyl n methylsulfoximine in 30 ml of tetrahydrofuran is cooled to 0 u00b0 c and treated with 4 9 ml of 3 m methylmagnesium chloride in tetrahydrofuran after 15 min at 0 u00b0 c the sulfoximine containing solution is cooled to 78 u00b0 c and added over 15 min to a stirred solution 78 u00b0 c of the reaction product of part b 2 8 g in 15 ml of tetrahydrofuran the reaction mixture is stirred for 1 hr at 78 u00b0 c then stirred into an ice saturated ammonium chloride water solution extracted with ethyl acetate washed successively with sodium bicarbonate and brine dried over anhydrous sodium sulfate and concentrated under reduced pressure to a residue 3 67 g this residue is then dissolved in a mixture of 12 ml of tetrahydrofuran 24 ml of water and 60 ml of acetic acid after stirring for 18 hrs at 35 u00b0 c the reaction mixture is then poured into brine extracted over ethyl acetate washed successively with brine aqueous sodium bicarbonate and brine dried over anhydrous sodium sulfate and concentrated under reduced pressure to a residue 4 9 g this residue in 160 mg of tetrahydrofuran 24 ml of water and 24 ml of acetic acid is added at 15 u00b0 c to aluminum amalgum.