Synthesis Of Organocatalyst Library And Its Application In The Asymmetrica-selenenylation Reaction

Part 1: Synthesis of Organocatalyst libraryOrganocatalyst is one of the research hotspots in the field of asymmetric catalysis,and chiral crown ether catalysts have been widely used in various asymmetric reactions such as kinetic resolution of silyl-protected secondary alcohols,β-elimination reaction,Michael addition,Mannich reaction et.al.In this part,a series of multifunctional chiral crown ether catalysts with different backbones was prepared and the catalytic activity was also tested.Moreover,various cinchona alkaloid derived amine-thiourea and squaramide catalysts was also synthesized.Establishment of catalysts library will make the research of subsequent enantioselective reactions more feasible.Part 2: Organocatalytic asymmetrica-selenenylation of α,β-unsaturated ketonesBased on the organocatalyst library,an organocatalytic asymmetrica-selenenylation of α,β-unsaturated ketones was developed.With a chiral squaramide as an efficient catalyst,the desired α-selenylated ketones were obtained in a good yield with the high enantioselectivity up to 89% ee,and good results could be obtained on a gram scale.The reaction condition is well tolerated to a wide range of substrates,including α,β-Unsaturated ketones with a range of aryl groups,heterocyclic units and alkyl groups.The product also could be efficiently transformed into useful building blocks with a propenylic stereocenter,the strategy presented in the study may suggest further applications in organic synthesis.