A new versatile synthesis of xanthines with variable substituents in the 1-, 3-, 7- and 8-positions

Article abstract of DOI:10.1055/s-1995-4082

A new convenient procedure for the synthesis of a wide range of xanthines has been developed starting from 3-substituted 6-aminouracils. Nitrosation and reduction yields the corresponding 5,6-diaminouracils, which are condensed with carboxylic acids. The resulting amides can be selectively alkylated at the uracil ring nitrogen N-1 (corresponding to xanthine N-3) under mild conditions. Ring closure and, if desired, alkylation at the 7-position, yields di-, tri-, or tetrasubstituted xanthines in high yields. Sensitive substituents, such as prop-2-ynyl, can be introduced in the 1-position. Variation of the 3-substituent is considerably facilitated in comparison with the standard procedure for the preparation of xanthines.