LAUSR

Mono-, di-, and tetramethylglycolurils were synthesized, isolated, and purified. For the first time, the cis- and the trans-isomers of N,N-dimethylglycoluril were isolated as individual substances by semi-preparative HPLC method. The structures of the synthesized compounds were confirmed by 1H NMR, 13C NMR, and HR–HPLC–MS. The EI mass spectra of individual substances were obtained by the GC–MS. Retention and resolution of N-methyl glycolurils were investigated in the reversed-phase HPLC mode for different stationary phases: C18, SB–Aq, and Luna 5u PFP(2). The retention of N-methyl glycolurils depended on the amount of CH3 groups and distance between the CH3 groups in the structure. The stationary phases provided different selectivity for glycoluril and its N-methyl derivatives due to different shape selectivity. Complete separation of the N-methyl derivatives of glycoluril was achieved in 4.5 min on the stationary phase with pentafluorophenyl propyl ligand in a gradient mode.Graphical abstract