As of 2018,[update] at least two such catalysts were commercially available: DMAPC5Ph5, a 1,2,3,4,5-pentaphenylferrocene-fused DMAP derivative, and PPY*, a 1,2,3,4,5-pentamethylferrocene-fused 4-pyrrolidinylpyridine derivative.:5578:542–543 A drawback of these catalysts is their limited production volume, as the 1996 synthesis route produces a racemate, requiring resolution via chiral HPLC. In 2020, a high-yield enantioselective synthesis of the two commercial catalysts, amongst other ferrocene-fused 4-dialkylaminopyridines, was achieved.