Nitrogen bridgehead compounds. Part 19. Synthesis of polymethylenepyrimidin-4-ones

Reaction of five-, six-, seven-, and eight-membered cyclic amidines ( 1 n = 0-3) with diethyl ethoxy-methylenemalonate ( 2 ) yields isomeric 2,3-polymethylene-4(3H]- and 1,2-polymethytlene-4(1H)-pyrimidinones ( 3 and 4 ) respectively, n = 0-3). With 2-aminopyrroline the isomer ratio was dependent upon the reaction conditions. The structure of the isomers 3 and 4 was studied by uv, ir and ¹H-nmr spectroscopy. Both isomers contain an active methylene group which can be deuterated. Deuteration was investigated with ¹H-nmr spectroscopy.