Parallel Microwave Synthesis of 2-Styrylquinazolin-4(3H)-ones in a High-Throughput, Platform Using HPLC/GC Vials as Reaction Vessels

The application of a high-throughput reaction platform for performing parallel microwave synthesis in sealed HPLC/GC vials contained in a strongly microwave-absorbing silicon carbide plate is described. The use of aluminum crimp caps with PTFE coated silicone septa in combination with an appropriate plate sealing mechanism allows processing of reaction volumes from 0.5-1.5 mL at temperatures of similar to 250 degrees C and pressures of up to similar to 20 bar. A library of 39 2-styrylquinazolin-4(3H)-one derivatives was prepared in a two-step/one-pot parallel fashion involving the initial three-component condensation of four anthranilic acids with acetic anhydride and ammonium acetate at 250 degrees C for 30 min. This was followed by catalyst-free condensation of the resulting 2-methylquinazolinones with a selection of 15 aromatic aldehydes. Compared to single-mode sequential microwave synthesis, the overall processing times for library synthesis could be significantly reduced.