Effect of α‐Hydrazino Acids on the Performance of H‐Pro–Pro‐Xaa Catalysts in the Conjugate Addition of Aldehydes to Nitroolefins

We demonstrated that tripeptides with the general structure H‐Pro–Pro‐ d ‐hVal‐R (R = OMe, OH, NH 2 ) are efficient stereoselective catalysts for the asymmetric conjugate addition of aldehydes to nitroolefins. The catalyst Pro–Pro‐ d ‐hVal‐OMe, which lacks an acidic group afforded γ‐nitroaldehydes in 79%–97% yield and 88:14–93:7 e.r. The assumed reaction mechanism relies on active role of hydrazide NH β or NH α protons in hydrogen bonding with the reacting species.