3-perhydrodiazin- 5-ylpyridinium ylide (3) reacts with N,N-dimethylaniline to give 5-((1,3-dimethyl-2,4,6-trioxo-hexahydropyrimidin- 5-yl)methyl)-5-(4-(dimethylamino)benzyl)-1,3- dimethylpyrimidine- 2,4,6(1H3H5H)-trione (6) in good yield. The crystal structure of 6 is reported Graphical Abstract Reaction of a Zwitterionic Pyridinium Ylide with N,N-Dimethylaniline
resonance chemical shifts reveals the molecular structure of a dimer that was obtained by an unexpected dimerization of 1,3‐dimethyl‐5‐methylenebarbituric acid. Furthermore, the puckering angle of the cyclobutane unit linking the six‐membered rings is discussed in detail. The influence of substituents on 1,3‐position of the cyclobutane ring on the puckering angle is demonstrated based on 1,1,3,3‐tetramethylcyclobutane