to that reported by compemolle tetrahedron 1993 49 3193 in 70 ml of methanol and 20 ml of water under a nitrogen atmosphere was added 0 55 g 13 11 mmol of lithium hydroxide the reaction was allowed to stir at room temperature for 2 hours the solvent was removed under reduced pressure the residue was diluted with water and washed with ethyl acetate the aqueous phase was acidified with 1n hydrochloric acid and extracted with ethyl acetate the organic phase was dried over magnesium sulfate filtration and removal of solvent afforded 2 0 g 98 2 of the title compound fab ms m h m z calcd 252 found 252 to a solution containing 1 04 g 4 14 mmol of 6 4 fluorophenyl 6 carboxymethylene 2 piperidinone in 25 ml of anhydrous dichloromethane under a nitrogen atmosphere at 0 u00b0 c was added 1 10 g 4 32 mmol of bopci and 0 80 ml 4 59 mmol of diea after stirring for 30 minutes a solution containing 1 1 g 3 53 mmol of 1 2 5 3 methylbenzyl 1 3 4 oxadiazolyl 2 s amino 3 methylbutan 1 ol hydrochloride in 10 ml of dichloromethane and 1 10 ml 6 31 mmol of diea the reaction was allowed to stir at 0 u00b0 c overnight the reaction was diluted with dichloromethane and washed with a saturated sodium bicarbonate solution the organic phase was dried over magnesium sulfate filtration removal of solvent under reduced pressure and column chromotography of the residue on silica gel with 10 methanol dichloromethane afforded 736 mg 41 0 of the title compound fab ms m h m z calcd 509 found.