A new type of dihydroquinazoline-based inhibitor of acetylcholinesterase (AChE) is described. These compounds were designed to interact with the catalytic site of AChE in a manner similar to the known inhibitor tacrine. In a manner analogous to the potency enhancement obtained by addition of chlorine atoms to the tacrine molecule, a 3-chloro derivative of the parent hexahydroazepino [2, 1-b] quinazoline structure was found to be ...