Synthesis, spectroscopic characterization and DFT calculations of monohydroxyalkylated derivatives of 1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione

Synthesis of new derivatives with an imidazo[1,5-c]quinazoline-3,5-dione ring has been presented. Two new alcohols with the imidazo[1,5-c]quinazoline-3,5-dione ring were obtained and characterized by spectral (1H, 13C NMR, IR and UV) and crystallography methods. A reaction chemoselectivity has been observed with a formation of monohydroxyalkyl derivatives of 1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione substituted at the 2. nitrogen atom. The absence of derivatives substituted at the 6. nitrogen atom was proven experimentally. The synthesis with chemoselectivity over 99% without control of the substituent effect happens very rarely. The HOMOeLUMO mappings are reported which reveals the different charge transfer possibilities within the molecule of 1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione in the region of the 2. and the 6. nitrogen atoms. Quantum-mechanical DFT calculations proved to be very useful to explain the reason of selectivity reaction of 1-phenyl-2H,6H-imidazo[1,5-c] quinazoline-3,5-dione with oxiranes.