Enantio- and Diastereoselective Asymmetric Addition of 1,3-Dicarbonyl Compounds to Nitroalkenes in a Doubly Stereocontrolled Manner Catalyzed by Bifunctional Rosin-Derived Amine Thiourea Catalysts

Starting from commercially available natural rosin derivatives, a class of bifunctional rosin-derived amine thiourea catalysts were designed and synthesized. The doubly stereocontrolled asymmetric addition of a variety of 1,3-dicarbonyl compounds to nitroalkenes was investigated. These rosin-derived chiral thioureas have been shown to serve as effective catalysts for this double-sterecontrolled organocatalytic process by the investigation of the efficacy of the thiourea catalysts in comparison with other thiourea catalysts reported. In addition, these chiral thiourea. ligands are easily available. Furthermore, the rosin-derived tertiary amine-thiourea was also revealed to be highly efficient for construction of contiguous stereogenetic centers containing an asymmetric quaternary carbon by the Michael reaction of alpha-substituted beta-ketoesters to nitroalkenes.