Diastereoselective Ugi reaction without chiral amines: the synthesis of chiral pyrroloketopiperazines

The three-component Ugi reaction with chiral 2-(2-formyl-1H-pyrrol-1-yl)acetic acids prepared from natural l-aminoacids was investigated. The reaction opens a new route to chiral substituted pyrroloketopiperazines. One of the first examples of an asymmetric Ugi reaction without chiral amines is described. The reaction proceeds with moderate diastereoselectivity to give the target compounds in good yields. The scope and limitation of the approach are discussed.