Mannich Reaction Catalyzed By Rosin-derived Thiourea Catalysts

These years the small molecular organic catalysts became more and more important because it's facile availability and enviroment benevolent. Among these catalysts, the thiourea catalyst, which control the stereoselectivity through H-bond between thiourea unit and substrate, showed its perfect catalytic activity in Michael, Henry, Mannich reaction and so on. Thus, more and more chemists pay their attention to the application of thiourea catalysts in the asymmetric synthesis. The Mannich reaction is one of the most versatile and attractive approaches for the construction of nitrogen-containing compounds in organic synthesis. Especially,/β-amino carbonyl derivatives represent a class of compounds that can be readily converted into valuable synthetic building blocks or biologically active molecules.An efficient doubly stereocontrolled organocatalytic method to access chiralβ-amino acids via asymmetric Mannich reaction with in situ generation of N-Boc imines by a new class of bifunctional rosin-derived tertiary amine thiourea catalysts has been established. These organocatalysts based on rosin have been proved to be the very effective promoters for this kind of catalytic asymmetric process and the reaction provides a convenient doubly stereocontrolled method to access synthetic usefulβ-amino acids with high optical purity.