ChemInform Abstract: Synthesis and anti‐Acetylcholinesterase Properties of Novel β‐ and γ‐Substituted Alkoxy Organophosphonates.

Abstract Activated organophosphate (OP) insecticides and chemical agents inhibit acetylcholinesterase (AChE) to form OP-AChE adducts. Whereas the structure of the OP correlates with the rate of inhibition, the structure of the OP-AChE adduct influences the rate at which post-inhibitory reactivation or aging phenomena occurs. In this report, we prepared a panel of β-substituted ethoxy and γ-substituted propoxy phosphonoesters of the type p- NO 2 PhO-P(X)(R)[(O(CH 2 ) n Z] (R = Me, Et; X = O, S; n  = 2, 3; Z = halogen, OTs) and examined the inhibition of three AChEs by select structures in the panel. The β-fluoroethoxy methylphosphonate analog (R = Me, Z = F, n  = 2) was the most potent anti-AChE compound comparable ( k i ∼6 × 10 6  M −1  min −1 ) to paraoxon against EEAChE. Analogs with Z = Br, I, or OTs were weak inhibitors of the AChEs, and methyl phosphonates (R = Me) were more potent than the corresponding ethyl phosphonates (R = Et). As expected, analogs with a thionate linkage (P S) were poor inhibitors of the AChEs.