Synthesis of some polycyclic noncondensed pyrimidine structures

α,ω-Bis(3,6-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-yl)alkanes and products of their cyclization, pyrimidinophanes: intra- and intermolecular interaction in crystals and in solutions

“…It should be noted that intensities of the molecular ion peaks of "open" bis(pyrimidinyl)alkanes of various structure sel dom exceed 25%. 16,17 In the mass spectra of pyrimi dinophanes, the [M -CH 3 ] + fragment ion is the only one in the region of high weights. In addition, formation of a double charged ion (z = 2) is characteristic of pyrimidino phanes 2a,b,d.…”