Lewis Acid Promoted, Nickel Cyanide Catalyzed Double Insertion of Carbon Monoxide in Reaction with Alkynols Using PEG-400 as a Phase-Transfer Agent. Role of Phase-Transfer Catalysts in Determining the Stereochemistry of the Reaction

Abstract

Alkynols can be converted to 2-alkylidenebutanedioic acids in excellent yield by Ni(CN)2-catalyzed reactions in toluene and 5.0 M aqueous NaOH under atmospheric pressure of CO at 95 °C, with polyethylene glycol (PEG-400) as the phase-transfer agent. This process is accelerated by the addition of certain Lewis acids, including CeCl3·7H2O, FeCl3, and LaCl3· 7H2O. The extent of conversion and the selectivity of the reaction are sensitive to the concentration of base. The stereochemistry for the formation of diacids using PEG-400 as the phase transfer agent is opposite to that found with quaternary ammonium salts. E-unsaturated diacids are the dominant products in all cases when PEG-400 is used as the phase-transfer agent.