Several new phospholipid-ara-C conjugates have been prepared and tested as prodrugs of the parent ara-C. The new derivatives include ara-CMP-L-dipalmitin, ara-CDP-L-distearin, ara-CDP-L-dimyristin, ara-CDP-L-diolein, and the radioactively labeled derivative ara-CDP- L-di [l-'4C] palmitin. In addition, the unusually stable ara-CMP-L-dipalmitin-N- phosphoryldicyclohexylurea adduct was isolated as a crystalline solid (two diastereomers) ...