SPD Silyl Ether-Catalyzed Asymmetric Friedel-Crafts Type Michael Addition Reaction

Azepine and indolizine,as important structural motifs,are embedded in many natural products,pharmaceuticals and synthetic building blocks.In recent years,the preparation of these frameworks has attracted much attention of organic chemists.Chiral secondary amine,one of the most commonly used organocatalysts for asymmetric reactions,has been applied for the construction of azepine and indolizine frameworks.It could simplify the process of synthesis and improve its atom economy efficiently with the employment of Friedel-Crafts type Michael addition reaction to construct these frameworks.Asymmetric catalysis is one of the most direct and effective method to construct a chiral center.In recent years,our group has designed a novel chiral SPD(spiro-pyrrolidine)silyl ether catalyst.Its asymmetrically catalytic effect and stereocontrol ability have been demonstrated by the Michael addition reaction and its cascade reactions.To further explore the unique advantages of the SPD-type catalysts,more reactions have being researched.Aimmed at this target,a catalytic asymmetric intramolecular Friedel-Crafts type Michael addition reaction therefore was selected in this dissertation by use of a mild SPD silyl ether for construction of azepine and indolizine derivatives.Initially this catalysis system was demonstrated to afford the excellent enantioselectivity and good yield.Subsequently,a wide range of substrates were surveyed to explore the generality of this reaction.As a result,substrates with both electron-withdrawing and electron-donating groups were tolerable and gave good yields and excellent enantioselectivities.