methyl ester formulae x and xi r 1 3 trifluoromethylphenyl m 1 ch 3 w 2 dimsyl sodium in dmso 80 ml was generated with 60 sodium hydride 1 60 g at 60 u00b0 65 u00b0 c during 2 hours cooled to 10 u00b0 c and 4 carboxybutyltriphenylphosphonium bromide 8 86 g was added the aldehyde from example 53 f 2 94 g was added to the ylide solution and reacted at ambient temperature for 18 hours the solution was poured into water neutral products were extracted with ethyl acetate and the aqueous phase was acidified the precipitated acids 3 51 g were filtered and esterified with 4 methanolic hydrogen chloride 200 ml for 2 hours to yield a mixture of the title compounds 3 7 g fractionation of 2 7 g of the geometric isomer mixture on silica gel 150 g with 9 1 skelly b ethyl acetate gave pure e isomer 1 81 g and pure z isomer 0 79 g as viscous oils the isomers were separately hydrolyzed in methanolic 50 ml sodium hydroxide for 6 5 hours concentrated in vacuo and acidified to yield 0 91 g of the z hexenoic acid m p 108 u00b0 c and 0 69 g of the e hexenoic acid m p 105 u00b0 c 5 1 3 trifluoromethylphenyl 4 5 6 7 tetrahydro.