Novel Benzylated (Pyrrolidin-2-one)/(Imidazolidin-2-one) Derivatives as Potential Anti-Alzheimer's Agents: Synthesis and Pharmacological Investigations

A series of N-benzylated (pyrrolidin-2-one)/(imidazolidin-2-one) derivatives were synthesized and evaluated for anti-Alzheimer's activity. The analogs were designed and synthesized on the basis of lead compound donepezil, which is currently prescribed as a major drug for the management of mild to severe Alzheimer's disease. Considering the structure activity relationship (SAR) of the lead compound, we first replaced the 5,6-dimethoxy-1-indanone moiety with N-benzylated (pyrrolidin-2-one)/(imidazolidin-2-one) (head) without depriving the key functionality interactions like carbonyl and dimethoxyphenyl and second substituted the spacer linkage (tail) in donepezil. The newly synthesized compounds were characterized by structural conformity and purity using various techniques. The compounds were then subjected to in vivo (behavioral studies) and in vitro (biochemical assays) evaluation using appropriate animal models against the standard drug. Compounds 3-(4-(4-fluorobenzoyl)-piperidin-1-yl)-1-(4-methoxybenzyl)-pyrrolidin-2-one (10b) and 1-(3,4-dimethoxybenzyl)-3-((1-(2-(trifluoromethyl)-benzyl)-piperidin-4-yl)-methyl)-imidazolidin-2-one (18c) displayed an excellent anti-Alzheimer's profile, while the rest of the compounds showed satisfactory results in comparison to donepezil.