A series of the novel C-5 alkynyl pyrimidine nucleoside analogues (1-14) in which the sugar moiety was replaced by the conformationally restricted Z- and E-2-butenyl spacer between the phthalimido and pyrimidine ring were synthesized by using Sonogashira cross-coupling reaction. Cytostatic activity evaluation of the novel compounds showed that E-isomers exhibited, in general, better cytostatic activities than the corresponding Z-isomers. E-isomer 14 exhibited the best cytostatic effect against all evaluated malignant cell lines, particularly against hepatocellular carcinoma (Hep G2, IC(50)=4.3microM). However, this compound was also cytotoxic to human normal fibroblasts (WI 38). Its Z-isomer 7 showed highly specific antiproliferative activity against Hep G2 (IC(50)=18microM) and no cytotoxicity to WI 38. Moreover, compounds 3, 4 and 14 expressed some marginal inhibitory activity against HIV-1 and HIV-2.

No abstract

The new pyrimidine derivatives of 2,3-O, O-dibenzyl-6-deoxy-L-ascorbic acid (8-10) were synthesized by condensation of uracil and its 5-fluoro- and 5-trifluoromethyl-substituted derivatives with 4-(5,6-epoxypropyl)-2, 3-O,O-dibenzyl-L-ascorbic acid (7), while pyrimidine derivatives of 4,5-didehydro-5,6-dideoxy-L-ascorbic acid (14-17) with free C-2' and C-3' hydroxy groups in the lactone ring were obtained by debenzylation of 11-13 with boron trichloride. Z-Configuration of the C4'=C5' double bond and position of the benzyl group in the lactone ring of 14 were deduced from their (1)H and (13)C NMR spectra and connectivities in COSY, ROESY, and HMBC spectra. The exact stereostructure of 13 was confirmed by its X-ray crystal structure analysis. Of all the compounds in the series, compound 16 containing a 5-fluoro-substituted uracil ring showed the most significant antitumor activities against murine leukemia L1210/0 (IC(50) = 1.4 microg/mL), murine mammary carcinoma FM3A/0 (IC(50) = 0.78 microg/mL), and, to a lesser extent, human T-lymphocyte cells Molt4/C8 (IC(50) = 31.8 microg/mL) and CEM/0 cell lines (IC(50) = 20.9 microg/mL).