Abstract
Ring expansion reaction and dehydrochlorination reaction of substituted-2-chloromethyl-3-aryl-4-oxo-1, 2, 3, 4-tetrahydroquinazolines (2a-g) were investigated. The required starting materials 2a-g were prepared from the corresponding 4 (3H) quinazolines (1a-g) by NaBH4 reduction in excellent yields. 2a-f were easily converted to dehydrochlorination products 3a-f in CHCl3 at room temperature. On the other hand, treatments of 2a-f with EtONa in EtOH afforded ring expansion products 4a-f. The mechanism of the ring expansion reaction was proved by the isolation of an intermediate, azirinoquinazoline (7). The investigation was extended to the reactions of azirinoquinazoline (7) with nucleophiles. The reactions with NaBH4, MeOH, AcOH, PhSH, and EtSH proceeded analogously to give benzodiazepines (8, 9, 10, 11, and 12).
