A modular synthesis of highly substituted imidazolium salts.

A versatile and modular one-pot method for the preparation of differently substituted symmetrical and unsymmetrical imidazolium salts is reported, and 19 examples are given. In the key step, readily available formamidines and alpha-halo ketones are coupled to give imidazolinium salts 3, followed by imidazolium salt formation by acylation-induced elimination. For many substitution patterns of the imidazolium salt products, this efficient strategy compares favorably with well-known processes in terms of yield, ease of synthesis, and robustness.