Structures of Dnacin A1 and B1: New Naphthyridinomycin‐Type Antitumor Antibiotics.

Dnacin A1 and B1 were revealed to be new naphthyridinomycin-type antitumor antibiotics with formulae of C20H23N5O4 and C19H24N4O5, respectively. The gross structure of dnacin A1 was elucidated by the spectroscopic analyses. Conversion of dnacin B1 into A1 by treatment with potassium cyanide indicated the presence of an α-carbinolamine moiety in dnacin B1. The relative stereochemistry of dnacins was clarified by analysis of the NOESY spectra.