ix solvent system used in thin layer chromatography is made up from ethyl acetate acetic acid 2 2 4 trimethylpentane water 90 20 50 100 according to m hamberg and b samuelsson j biol chem 241 257 1966 a solution of diethyl malonate 30 3 g in 600 ml of tetrahydrofuran is treated with potassium tertiary butoxide 10 52 g for 5 min at about 25 u00b0 c thereupon u03b1 u03b1 39 dibromo m xylene 25 0 g is added and the mixture stirred at ambient temperature for 2 5 hr the reaction is quenched by addition of 100 ml of water and 50 ml of 5 hydrochloric acid the mixture is extracted with diethyl ether and the organic phase is dried over sodium sulfate and concentrated to an oil the crude product 45 3 g is subjected to silica gel chromatography eluting with skellysolve b and then skellysolve b ethyl acetate 90 10 yield of title compound 20 2 g having nmr spectral peaks at 7 17 4 40 4 34 3 96 and 1 38 1 06 u03b4 the formula xxii m bromomethyl benzyl malonate diethyl ester preparation 1 20 9 g is treated with 20 ml of 48 hydrobromic acid on a steam bath for 20 hr the reaction mixture is diluted with 200 ml of water and extracted with diethyl ether.