The Chemoselective Fischer’s Synthesis of Indolenine Derivatives By iso-Butyric Acid As A Weak Organic Acid Catalyst

Iso-butyric acid as a new, simple, and expensive solvent/catalyst was successfully used for the chemoselective Fischer’s synthesis of indolenines derivatives 3a-r by one-pot condensation reaction of various phenylhydrazines 1a-e with the substituted acetophenones 2a-c at reflux conditions. In this protocol, all products 3a-r were obtained in high yields and short reaction time. The structures of the product were established with spectroscopic data of 1H NMR, 13C-NMR, and FT-IR.