Novel N-benzylpiperidine carboxamide derivatives as potential cholinesterase inhibitors for the treatment of Alzheimer's disease

A series of fifteen acetylcholinesterase inhibitors were designed and synthesised based upon the previously identified lead compound 5,6-dimethoxy-1-oxo-2,3-dihydro-1H-inden-2-yl 1-benzylpiperidine-4-carboxylate (5) which showed good inhibitory activity (IC50 0.03 ± 0.07 μM) against acetylcholinesterase. A series of compounds were prepared wherein the ester linker in the original lead compound was exchanged for a more metabolically stable amide linker and the indanone moiety was exchanged for a range of aryl and aromatic heterocycles. The two most active analogues 1-benzyl-N-(5,6-dimethoxy-8H-indeno[1,2-d]thiazol-2-yl)piperidine-4-carboxamide (28) and 1-benzyl-N-(1-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl) piperidine-4-carboxamide (20) afforded in vitro IC50 values of 0.41 ± 1.25 and 5.94 ± 1.08 μM, respectively. In silico screening predicts that 20 will be a blood brain-barrier permeant, and molecular dynamic simulations are indicative of a close correlation between the binding of 20 and the Food and Drug Administration-approved cholinesterase inhibitor donepezil (1). [Display omitted] •Series of carboxamide's prepared exchanging the indanone ring system of donepezil.•Two selective AChE inhibiting scaffolds identified with IC50 values below 6 μM.•Molecular docking shows binding interactions comparable with donepezil.•Molecular dynamics simulations reveal subtle differences in interactions.•ADME predictions suggest most scaffolds will be blood brain barrier permeants.