CO[C:3](=[O:19])[CH2:4][C@H:5]([OH:18])[CH2:6]OS(C1C=CC(C)=CC=1)(=O)=O.C(OC(=O)C[C@H](O)CI)C.C(OC(=O)C[C@H]1CO1)C.C(O)(=O)[C@H](CC(O)=O)O.[CH2:48]([NH2:51])[C:49]#[CH:50]>>[OH:18][C@@H:5]1[CH2:6][N:51]([CH2:48][C:49]#[CH:50])[C:3](=[O:19])[CH2:4]1In accordance with Scheme I, (S)-3-hydroxy-4-[[(4-methylphenyl)sulfonyl]oxy]butanoic acid methyl ester 2, (S)-3-hydroxy-4-iodobutanoic acid ethyl ester 3 and (S)-oxiraneacetic acid ethyl ester 4 are prepared from (S)-malic acid 1 using previously described methods [S. Saito et. al. Chem. Lett. 1389, (1984) and M. Larcheveque et. al. Tetrahedron Lett. 1781, 28 (1987)]. The esters 2, 3 and 4 are individually reacted with propargylamine in an alcohol solvent at temperatures ranging from room temperature to the reflux temperature of the solvent, preferably in the presence of an alkali metal carbonate, to produce (S)-4-hydroxy-1-(2-propynyl)-2-pyrrolidinone 5. Compound 5 is then reacted with an aryl or a (C1 -C6) carboxylic acid anhydride such as acetic anhydride in the presence of pyridine and preferably dimethylaminopyridine in an ether or a chlorohydrocarbon solvent, such as dichloromethane, to give the intermediate of general formula 6, for example, (S)-4-(acetyloxy)-1-(2-propynyl)-2 -pyrrolidinone.
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