5-Fluorouracil Derivatives. IV. Synthesis of Antitumor-Active Acyloxyalkyl-5-fluorouracils

The toxicity and tumor affinity of 5-fluorouracil (1) have been modified by the introduction of acyloxyalkyl group (s) at the 1-, 3- or 1, 3-position (s) of 1. 1-Acyloxyalkyl-5-fluorouracil (3), 3-acyloxyalkyl-5-fluorouracil (4) and 1, 3-bis (acyloxyalkyl)-5-fluorouracil (5) were obtained by three methods : i) the reaction of α-chloroalkyl carboxylate (2) with 1, ii) the reaction of alkylidene diacylate with 2, 4-bis (trimethylsilyloxy)-5-fluoropyrimidine, iii) partial hydrolysis of 5. Compounds 3, 4 and 5 showed antitumor activity.