THE PROCESS FOR THE PREPARATION OF PENEM COMPOUND

Novel phenem cpd., (5R, 6S, 8R, 2'R)-2-(2'tetrahydrofuryl)-6-(1-hydroxyethyl)-2-phenem-3-carboxylic acid, of formula (I) and its pharmaceutical salts are prepd. by : dissolving and heating oxalic imide cpd. of formula (III) in inactive organic solvent, then intramolecular wittig cycling-reacting that with arylphosphonos acid diester to prepare the phenem cpd. of formula (IV) to be protected with its each functional gp.; step by step forming the cpd. of formula (V), or at the same time deprotection; and converting to its salts form. In the formulas, R1 is hydroxyl protecting gp., esp. t-butyldimethylsilyl; R2 is carboxyl protecting gp., esp. aryl, P-nitrobenzyl or 2-(trimethylsilyl) ethyl; M is alkali metal, esp. Na or K. The obtd. phemen cpd. has good antibacterial property, then is useful as a antimicrobial drug.