Olefin Metathesis in the Ionic Liquid 1‐Butyl‐3‐methylimidazolium Hexafluorophosphate Using a Recyclable Ru Catalyst: Remarkable Effect of a Designer Ionic Tag

Abstract

Designer labels: Ruthenium carbene complex 1 bearing an ionic tag was shown to be a highly reactive catalyst for the ring-closing metathesis of various diene and enyne substrates in minimally ionic solvent systems (see scheme; Bmim=1-butyl-3-methylimidazolium, Ts=toluene-4-sulfonyl). The catalyst can be repeatedly recycled and reused (up to at least 10 cycles) without significant loss of its activity, whereas other catalysts tested exhibited a dramatic diminishment in their activity upon recovery from the ionic layer.