The Clinically used antitumor agent, 5-(3,3-dimethyl-1-triazeno)-imidazole- 4-carboxamide (DTIC), is well known for its instability and its tendency toward photodecomposition. It has been suggested that these products, of photodecomposition, might be responsible for severe side effects (such as nausea and vomiting), observed in various cancer patients. Attempts to circumvent this problem have resulted in several-investigators synthesizing more stable analogues, of DTIC, by replacing the imidazole ring with other aryl groups. Several of these compounds have antitumor activities comparable to that of DTIC and appear to be less toxic. The recent discovery, of an unusual decarboxylation of thiophene diazonium carboxylates, has opened an indirect pathway, to the possible synthesis of a new series of compounds, which might be expected to have a wide range of antitumor properties. Accordingly, a specific objective of this proposed research, is to replace the imidazole ring of DTIC with the, previously unused, thienopyrimidine system. Significant antitumor activities have been observed, from other derivatives of this system. The usual direct approach to the synthesis of these triazenes can not be taken, due to the elusive nature of the unsubstituted thiophene diazonium salt precursors. By employing the use of diazonium carboxylates, the synthesis, and studies on the chemical, and biological activities of several 6-(3,3-dialkyl-1- triazeno)-thieno-[2,3-d]pyrimidine-2,4-(1H,3H)-diones, and a series of 3- (3,3-dialkyl-1-triazeno)thiophenes, are proposed. These new series, of potential tumor inhibitory triazenes, will be submitted to the National Cancer Institute to be tested against human cancer cell lines; and to be included in the broad-based screening program for the identification of potential AIDS antiviral agents.
