1) The reaction of benzhydryl 2alpha-methyl-2beta-(chloromethyl)penam-3alpha-carboxylate (I) with sodium azide in DMF gives the corresponding azidomethyl derivative (II), which is oxidized with KMnO4 in aqueous acetic acid to the dioxide (III). The cyclization of (III) with trimethylsilylacetylene (IV) at 95 C yields benzhydryl 2a-methyl-2B-(4 trimethylsilyl-1,2,3-triazol-1 ylmethyl)penam 3a-carboxylate-1,1-dioxide (V), which is desilylated with KF and 18-crown-6 in hot DMF affording the benzhydryl ester of YTR-830 (VI). Then this compound is submitted to hydrogenolysis with H2 over Pd/C in ethyl / acetate / water.

2) The ester (VI) can also be obtained by cyclization of (III) with vinyl acetate (VII) at 110 C.

The title amide is obtained by condensation of 6-methylpyridine-3-carboxylic acid (I) with 4-ethoxy-2-nitroaniline by means of cyanuric chloride and TEA in dichloromethane.