Yb(OTf)3 (0.20 mmol, 5.0 mol%) and homotrimethylbenzene (5.0 mL) were added to a 20 mL Pyrex flask equipped with a magnetic stirring bar and a reflux condenser under argon protection, using 2-amino-5-chlorobenzamide (1, 4.0 mmol) and formamide (2, 6.0 mmol). The reaction mixture was stirred at 120-165 °C (bath temperature) for 6 hours. After completion of the reaction, the mixture was cooled to room temperature and analyzed by GLC, GC-MS (EI) and LC-MS (ESI). After removal of homotrimethylbenzene by evaporation under vacuum, the product 6-chloroquinazolin-4-one (3) was separated by recrystallization from MeOH/hexanes and/or silica gel medium pressure column chromatography (eluent: EtOAc/hexanes = 50/50 to 100% EtOAc. for 3j, eluent: MeOH/CHCl3 = 50/50). The structures of the products were confirmed by 1H NMR (400 MHz, DMSO-d6) and 13C NMR (100 MHz, DMSO-d6) spectra. The analytical and spectral data of compounds 3a-e, 3f, 3g, 3h and 3j were in agreement with literature reports. The characterization data of product 3i are given below.
