Sycnthesis of quinazoline analogues of folic acid modified at postion 10.

The quinazoline couterpart of folic acid (5,8-deazafolic acid) as well as its 10-methyl analogue has been shown to be an effective inhibitor of thymidylate synthetase from several different sources. This paper describes the synthesis of modifications in which the nitrogen atom at position 10 is replaced by sulfur, oxygen, or methylene affording 10-thia-5,8-deazafolic acid, 10-oxa-5,8-deazafolic acid, and 5,8,10-deazafolic acid, respectively. In preliminary testing, each of the target compounds displayed marginal activity against L1210 leukemia in mice.