The 5-fluorouracil derivatives of the present invention are novel compounds undisclosed in literature.
We carried out extensive research in an attempt to improve the antitumor action of known 5-fluorouracils and 2'-deoxy-5-fluorouridines and to render them less toxic, and succeeded in synthesizing a class of novel 2'-deoxy-5-fluorouridines which are substituted at the 3'- and/or 5'-position with a phenyl-lower alkyl group having a specific substituent, heterocyclic lower alkyl group optionally having a specific substituent or unsaturated heterocyclic group optionally having a specific substituent; and a class of novel 5-fluorouracils which are substituted at the 1-position with a lower alkyl group having a specific substituent and which have a specific acyl group introduced into the 3-position. We have found that these novel compounds are outstanding in anticancer action, absorption, long lasting effect and therapeutic index, low in toxicity, and therefore very useful as antitumor agents.
We have also successfully synthesized novel compounds which are usable as intermediates for synthesis of said novel compounds useful as antitumor agents.