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

•New monohydroxyalkyl derivatives of 1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione were prepared.•Structure of single crystal of 2-(2-hydroxypropyl)-1-phenyl-6H-imidazo[1,5-c]quinazoline-3,5-dione was determined.•High chemoselectivity of reaction was explained by quantum-mechanical calculation (DFT).

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 HOMO–LUMO 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.

Graphical abstractCompounds with imidazoquinazoline ring are widely used in pharmacy and medicine due to their versatile biological properties. These compounds also exhibit high thermal stability which makes them potential substrates for synthesis of thermally stable polymers. In this work two new hydroxyalkylated derivatives of 1-phenyl-2H,6H-imidazo[1,5-c]quinazoline-3,5-dione are presented. The synthesis of the potential modifiers of the thermal properties of polymers proceeds with chemoselectivity over 99% without control substituent effect. The quantum-mechanical calculations allowed to explain this phenomenon.Figure optionsDownload full-size imageDownload as PowerPoint slide