The N-protected pyrimidine moieties of bleomycin (pyrimidoblamic acid, 1) and epibleomycin are reported. In addition to a complete description of a synthetic route outlined earlier (Arai, H.; Hagmann, WK; Suguna, H.; Hecht, SM J. Am. Chem. SOC 1980, 102, 6631), a new route is also presented that provides access to multigram quantities of pyrimidoblamic acid. Because bleomycin and epibleomycin, which differ only in the orientation of the ...