With the aim of diminishing the toxicity of 5-fluorouracil (1) and obtaining biologically active derivatives of 1 suitable for oral administration, α-alkoxyalkyl groups were introduced at the 1-, 3-and 1, 3-positions of 1. Alkoxyalkylation can be effected by four methods : (i) reaction of 1-alkoxyalkyl chloride (2) with 1, (ii) reaction of acetal with 2, 4-bis (trimethylsiloxy)-5-fluoropy-rimidine, (iii) addition reaction of α-unsaturated ether with 1, (iv) aminolysis of 1-alkylthio-carbonyl-3-(1-alkoxyalkyl)-5-fluorouracil. The toxicity of the products was less than that of 1, and some of these compounds showed moderate antitumor activity against L-1210 leukemia.
Novel N-phthalidyl-5-fluorouracil derivatives represen- led by the following formula:
wherein one of R, and R2 represents a phthalidyl group of
(wherein R3 represents a hydrogen atom, a halogen atom, an alkoxy group or an alkyl group) and the other represents a hydrogen atom, an acyl group or a cyclic ether group of
(n: 1 or 2), or R, and R2 represent the same phthalidyl group of
(wherein R3 is the same as defined above). They have antineoplastic effects with less toxicity, thus used as carcinostatic agents.