Damp CuI from the first step (or commercial CuI) and potassium iodide were dissolved in acetonitrile with a small amount of ascorbic acid added to prevent the oxidation of Cu(I) to Cu(II). A solution of pyridine (1a) in acetonitrile was added, turning the clear yellow solution milky, due to the incipient formation of the insoluble cluster (Scheme 1)