PYRIMIDINES-19. RING TRANSFORMATION OF 5-NITROURACIL INTO NITRORESORCINOLS

Article abstract of DOI:10.1016/0040-4020(82)80220-2

The first intermolecular ring transformation of a uracil derivative into benzene system is reported.Treatment of 1,3-dimethyl-5-nitrouracil (1) with acetone in NaOMe/MeOH afforded 6-acetonyl-5,6-dihydro-1,3-dimethyl-5-nitrouracil (6) wich was converted into 4-nitroresorcinol (5) upon treatment with NaOEt/EtOH at reflux.Reaction of 1 with butanone gave two major products, 3-(5,6-dihydro-1,3-dimethyl-5-nitrouracil-6-yl)-butanone (7) and 1-(uracil-6-yl)butanone isomer (8).Prolonged treatment of 7 with NaOEt/EtOH afforded 4-methyl-6-nitro-resorcinol (9) whereas 8 was converted into 2-methyl-4-nitro-resorcinol (10).Treatment of 1 with diethyl acetonedicarboxylate in NaOEt/EtOH afforded diethyl-2-(5,6-dihydro-1,3-dimethyl-5-nitrouracil-6-yl)-acetonedicarboxylate (2).Prolonged treatment of 2 with NaOEt/EtOH at reflux afforded (5,6-dihydro-1,3-dimethyl-6-nitrouracil-6-yl)acetic acid (3).Apparently, 2 underwent a retroClaisen reaction to give 3.Reaction of 1 with ethyl acetoacetate in NaOEt/EtOH gave adduct isomers 4 which underwent transformation reaction to give eventually 6-nitroresorcinol (5).