Reductive condensation of 1,4-butanediamine (I) with glyoxylic acid (II) affords 3,8-diazaoctanoic acid (III). Subsequent acylation of diamino acid (III) with 2,3-diacetoxybenzoyl chloride (IV) provides diamide (V). After activation of (V) as the corresponding mixed anhydride with either methyl or isobutyl chloroformate, condensation with ampicillin (VI) yields the title compound.