 Reaction of aryl aldehyde 26 with two equivalents of 2-acetylpyridine (27) yielded terpyridines of the form 28.In addition to variations on the original method, a number of combinatorial studies using the Kröhnke synthesis and its variations have been employed to synthesize vast libraries of highly functionalized pyridines.Janda and co-workers utilized the general Kröhnke reaction scheme to generate a 220 compound library.