The D-threonine (I) is converted into the azetidinone (II), and into the enol (III) according to (Tsubouchi, H., et al. Tetrahedron Assimetry, 1944, 5: 441). The tosylation of (III) with tosyl chloride and N-methylpyrrolidine yielded the tosylated enol (IV), which was cyclized with H2S and triethylamine to the isocephem derivative (V). The chlorination of (V) with N-bromosuccinimide (NBS) and AIBN affords the bromomethyl derivative (VI), which is treated with 2-(4-methyl-2-sulfanylthiazol-5-yl)acetic acid (VII) and triethylamine or NaHCO3 and then esterified with diphenyldiazomethane to give the expected condensation product (VIII). The reaction of (VIII) with methylhydrazine cleaves the phthalimide group affording (IX), which is then amidated wih the acetic acid derivative (X) by means of dicyclohexylcarbodiimide (DCC) givig the fully protected final product (XI). Finally, this compound is treated with trifluoroacetic acid to eliminate the diphenyl nad triphenyl protecting groups.