Synergistic Palladium-Phosphoric Acid Catalysis in (3 + 2) Cycloaddition Reactions between Vinylcyclopropanes and Imines

Catalysts

Martina Mamone¹  Vasco Corti¹  Alessandro Giungi¹  Mariafrancesca Fochi¹  Enrico Marcantonio¹  Luca Bernardi¹ 

[1] Department of Industrial Chemistry “Toso Montanari” and INSTM RU Bologna, Alma Mater Studiorum—University of Bologna, V. Risorgimento 4, 40136 Bologna, Italy;

关键词: (3 + 2) cycloaddition;    vinylcyclopropane;    palladium catalysis;    h-bond catalysis;    imine;    stereoselective synthesis;    pyrrolidine;    synergistic catalysis;   

DOI  :  10.3390/catal10020150

来源: DOAJ

【 摘 要 】

The palladium-catalyzed (3 + 2) cycloaddition reaction between vinylcyclopropanes (VCPs) bearing geminal EWG’s and imines represents a straightforward and flexible entry to polysubstituted pyrrolidine derivatives. In this paper, we demonstrate that using a synergistic catalysis approach, based on the combination of phosphoric acid and palladium catalysts, it is possible to engage for the first time N-aryl and N-benzyl imines in this cycloaddition reaction. A range of polysubstituted pyrrolidines is obtained with moderate to good yields and diastereoselectivities, using a simple palladium species (Pd(PPh₃)₄) and an archetypical phosphoric acid as catalyst combination. A two-step scheme which exploits the same palladium catalyst for two consecutive and mechanistically distinct reactions (the cycloaddition and a Suzuki−Miyaura cross-coupling) is also presented. This synergistic catalysis approach is well posited for the development of the enantioselective version of this reaction. A screening of common BINOL-derived chiral phosphoric acids as catalyst component identified a species giving the product with moderate, yet promising, enantioselectivity (64% ee).

【 授权许可】

Unknown