NHC-Catalyzed Aza-Benzoin Condensation of N,N'-Dipyridin-2-yl Aminals with Aldehydes.

α-Amino ketones are useful compounds because of their synthetic utility and bioactivities. After observing the ability of N,N'-dipyridin-2-yl aminals to form imines in situ, the synthesis of α-amino ketones using N,N'-dipyridin-2-yl aminals was proposed. Through the NHC-catalyzed aza-benzoin reaction between aromatic/aliphatic aldehydes and N,N'-dipyridin-2-yl aminals, α-amino ketones, including aromatic, heterocyclic, and aliphatic versions, were synthesized with yields up to 99%. A direct route toward N-Boc-protected α-amino ketones from N,N,N'-tris-Boc aminals was also discovered, yielding the desired N-Boc-protected α-amino ketones in yields up to 73%.