Reaction of methyl (2E)-3-dimethylamino-2-(1H-indol-3-yl)-propenoate with ureas: facile entry into the polycyclic meridianin analogues with uracil structural unit
propenoate with various (thio)ureas in the presence of an acid 2-(1H-indol-3-yl)-3-(3-substituted(thio)ureido)propenoates were obtained in high yields. A base promoted cyclization of these (thio)ureidopropenoate derivatives afforded 5-(indol-3-yl)-3-substituted-pyrimidine-2,4-diones which represent a new family of meridianine analogues.