Methylpyrimidin—Pyridin-Umlagerung von Dihydro-6-methyl-2 (1H)-pyrimidinthionen bzw.-onen

1-Unsubstituted dihydro-6-methyl-2(1H)-pyrimidinethiones undergo an aminolysis in dialkylformamides or methylformamide resp., at higher temperature, and then are rearranged to 4-dialkylaminodihydro-2(1H)-pyridinethiones6 a, b or the 4-methylamino compound6 c. 1-Alkyl- and 1-aryldihydro-6-methyl-2(1H)-pyrimidinethiones1 b, c and tautom, methylenecompounds2b,c resp., react at the same conditions withDMF not only to 4-alkylamino-or 4-arylaminodihydro-2(1H)-pyridinethiones6 c, d but also to 4-dimethylaminodihydro-2(1H)-pyridinethiones6 a. From 3-substituted dihydro-6-methyl-2(1H)-pyrimidinethiones only the 3-aryl compound12 b is converted byDMF to the corresponding dihydro-4-dimethylamino-1-phenyl-2(1H)-pyridinethione14. Also 4-alkylamino- and 4-arylaminodihydro-2(1H)-pyridones18a, b are formed by heating inDMF at 230°C from 1-alkyl- and 1-aryldihydro-2(1H)-pyrimidinones15b, c and of methylene compounds16b, c resp. 2-Methylimino- and 2-phenyliminodihydro-1,3-thiazinethiones19a, b react inDMF viaDimrothrearrangement to the corresponding 1-alkyl- and 1-phenyl-dihydro-2(1H)-pyrimidinethiones1 b, 2 b, 1 c, 2 c and further to 4-alkylamino-and 4-arylaminodihydro-2(1H)-pyridinethiones6 c, d.