A Synthesis of α-Lithiated Enol Ethers from α-Arenesulfinyl Enol Ethers: Ni(0)- and Pd(0)-Catalysed Coupling of Enol Triflates and Phosphates Derived from Lactones with Sodium Arenethiolates Gives α-Arenesulfanyl Enol Ethers

Abstract

A three-step synthesis of stable and storable α-benzenesulfinyl enol ethers from lactones entails (a) conversion of a lactone to an enol triflate or phosphate; (b) Ni(0) and Pd(0) cross-coupling of the enol triflate or phosphate with a sodium arenethiolate to give an α-arenethio enol ether; and (c) oxidation of an arenethio group to a sulfoxide. The α-benzenesulfinyl enol ethers undergo sulfoxide-lithium exchange on reaction with n-BuLi to give α-lithiated enol ethers thus making the α-benzenesulfinyl group a surrogate for the trialkylstannyl group which has hitherto served as the most common precursor to α-lithiated enol ethers.