HETEROCYCLIC STUDIES .9. SYNTHESIS AND COVALENT HYDRATION OF 4-TRIFLUOROMETHYLPTERIDINE AND SOME METHYL DERIVATIVES

Syntheses of 4-trifluoromethylpteridine and its 7-methyl and 6,7-dimethyl derivatives are described. The first two are essentially completely hydrated across the 3,4-bond, at equilibrium in neutral aqueous solution, and the last is partly hydrated. The isolation of all the 3,4-hydrates as stable solids is described. Dissolution of 4-trifluoromethylpteridine in aqueous acid led largely to 5,6:7,8-dihydrated cations which rearranged to 3,4-hydrated cations, but its methyl derivatives gave 3,4-hydrated cations directly. The factors which influence the ease and position of hydration are discussed. 1H N.m.r. and u.v. spectra are tabulated.