Pteridines. Part XLII. Synthesis and Properties of 8-Substituted 2,4-Dithiolumazines

Article abstract of DOI:10.1002/hlca.19890720415

Condensation reactions of the 5-amino-6-(subst. amino)-2,4-dithiouracils 12 and 13 with diacetyl or benzyl led to the 6,7,8-trisubstituted 2,4-dithiolumazines 14-16.Methylation of these compounds affected both thio functions forming various types of 2,4-bis(methylthio)lumazine derivatives depending on the nature of the substituents at C(7) and N(8).The 6,7,8-trimethyl-2,4-dithiolumezine (14) was converted into 7,8-dihydro-6,8-dimethyl-7-methylidene-2,4-bis(methylthio)-pteridine (17), whereas the 8-methyl-6,7-diphenyl-(15) and the 8-(2-hydroxyethyl)-6,7-diphenyl-2,4-dithiolumazine (16) yielded the corresponding covalent inter- or intramolecular 7,8-adducts 18-21.The unusual structures were proven by spectroscopic means and those of the alcohol adducts 20 and 21, furthermore, confirmed by X-ray analysis.