A series of novel substituted thiochromones and thiochroman-4-ones was synthesized. Compounds were designed as analogues of naphthoquinone and as potential "bioreductive alkylating agents" and were tested for antitumor activity. The lead compound, 3-(chloromethyl)thiochromone 1,1-dioxide (4), inhibited Ehrlich ascites tumor growth by 100% in CF1 male mice at 10 (mg/kg)/day ip. Similarly, 18 of the 29 related compounds demonstrated good activity in this tumor screen. Few definitive structure-activity correlations were evident regarding the nature of the 3-substituent. However, the 2,3 double bond and a sulfone or sulfoxide were required for activity. Four of the compounds synthesized showed marginal but significant activity against P-388 lymphocytic leukemia.

To test the effect of changes in electronegativity within the alicyclic N-1 substituent 5-fluorouracil analogues on cytotoxic activity, a series of derivatives of ftorafur, 1-(2'-tetrahydrofuranyl)-5-fluorouracil, was synthesized and tested for antitumor activity in the P388 lymphocytic leukemia screen and cytotoxic activity in the L1210 cell culture screen. Two compounds of N-1 substituent with high electronegativity, the 2'-tetrahydrothiophene 1'-oxide and the 2'-tetrahydrothiophene 1',1'-dioxide derivatives, demonstrated the highest in vitro L1210 cell inhibition (84.5% and 92.0%, respectively). Furthermore, against P388 lymphocytic leukemia in vivo, the 2'-tetrahydrothiophene 1'-oxide derivative showed significant activity (T/C = 143). Other compounds of similar or lower electronegativity within the N-1 cyclic substituent were inactive against P388 lymphocytic leukemia and less active against L1210 cells.

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Cultured L1210 murine lymphocytic leukemia cells were used to compare metabolic activation and cytotoxicity of 5-fluorouracil (FU), Ftorafur (FT), and three novel FU-sulfur analogues. These analogues, 1-(2'-tetrahydrothienyl)-5-fluorouracil (FUS), 1-(2'-tetrahydrothienyl)-5- fluorouracil-1'-oxide (FUSO), and 1-(2'-tetrahydrothienyl)-5-fluorouracil-1'-1'-dioxide (FUSO2), have yet to be fully evaluated for potential therapeutic value based on in vitro cytotoxicity. The role of these FU analogues as prodrugs was evaluated by comparing metabolism of normal pyrimidine pathways and activation by hepatic mixed function oxidases (MFO). Significant differences in biochemical activity and cytotoxicity were measured between FU and FU analogues. FU and FU analogues were cytotoxic to L1210 cells (63-92% growth inhibition of 100 microM concentrations after 72 hr of incubation). However, at equimolar concentration cytotoxicity of the FU analogues after MFO activation (56-66% growth inhibition) was greater than FU (47% growth inhibition). Hypoxanthine, a purine precursor, did not significantly alter fluoropyrimidine cytotoxicity with or without MFO. Thymidine and uridine, pyrimidine precursors, reduced FT and FUS cytotoxicities in the presence (27, 40%) and absence (25, 15%) of MFO but did not modify FU, FUSO, or FUSO2 cytotoxicities.

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Ausgehend vom Thiochromanon (Ia) wird über das Thiochromondioxid (IIIb) die Chlormethylverbindung (IV) hergestellt, die zu den Substitutionsprodukten (VI)‐(XI) umgesetzt wird.