Cholinesterase inhibitory activity and regioselective synthesis of spiropyrrolidinoindole integrated ferrocene hybrid heterocycles via multicomponent cycloaddition reaction

A novel spiroheterocyclic hybrid comprising several privileged structures comprising pyrrolidine, quinoxaline, indole and ferrocene moieties were synthesized in good yields in sustainable fashion using [Bmim]Br augmented four component cycloaddition process. A relatively less explored ylide prepared from quinoxalinone and L-tryptophan with diverse ferrocenyl derivatives in ionic liquids afforded spiropyrrolidinoindole tethered ferrocene hybrids. The reaction provides highly regioselective fashion thus created five new bonds and four adjoining stereocenter in single synthetic transformation, thus created with complete diastereomeric control. The cholinesterase inhibitory potency was performed for synthesized compounds against AChE/BChE enzymes. Among them, compound bearing with fluorine substituted heterocycles showed significant activity which is comparable activity with reference standard, galantamine.