Synthesis of an N-mesityl substituted chiral imidazolium salt for NHC-catalyzed reactions.

A new synthetic approach to chiral imidazolium salts makes possible the first synthesis of an N-mesityl substituted, aminoindanol-derived N-heterocyclic carbene precursor, 1.ClO4. The successful synthesis allows the first direct comparison of otherwise identical imidazolium and triazolium precursors across a number of NHC-catalyzed processes. These studies confirm striking differences in reactivity and mechanism between the two classes.