Synthesis and properties of 7-hydroxyxanthine and its derivatives
Use of an improved procedure for the synthesis of 7-hydroxyxanthine has enabled the synthesis of 7-hydroxy-1-methylxanthine and several 8-alkyl derivatives. The reactivity of 7-hydroxyxanthine and 7-hydroxy-1-methyl-xanthine towards acetic anhydride has been compared with that of 3-hydroxyxanthine. The 8-alkyl derivatives, which have the same electronic and tautomeric properties as the 8-unsubstituted compounds were more soluble in organic solvents. Reduction of the N-hydroxy-group in these derivatives gave xanthines soluble in organic solvents. U.v. and n.m.r. spectra and dissociation constants are discussed.