Silyl Fluoride Electrophiles for the Enantioselective Synthesis of Silylated Pyrrolidine Catalysts
作者:Kaleb I. Jentzsch、Taewoo Min、Jennifer I. Etcheson、James C. Fettinger、Annaliese K. Franz
DOI:10.1021/jo200991q
日期:2011.9.2
Chiral silylated pyrrolidine catalysts are obtained in high yield and enantioselectivity by sparteine-mediated lithiation of N-Boc-pyrrolidine and addition to silyl fluoride electrophiles. The activity and enantioselectivity of a new tert-butyldiphenylsilylpyrrolidine catalyst has been demonstrated for various asymmetric Michael reactions at 5 mol % catalyst loading and affords up to 99% ee for asymmetric
手性甲硅烷基化的吡咯烷催化剂是通过斯巴丁胺介导的N -Boc-吡咯烷的锂化反应以及添加到氟硅烷亲电子试剂中而获得的,具有高收率和对映选择性。新的活性和对映选择性叔丁基丁基二苯基甲硅烷基吡咯烷催化剂已在5摩尔%的催化剂负载量下用于各种不对称迈克尔反应,并为与醛和硝基烯烃的不对称迈克尔反应提供了高达99%ee。乙醛供体的产率高达77%,对映选择性高达ee的96%,避免了通常会降低产率的常见副反应。通过证明通过与催化剂胺形成氢键加合物来活化硝基受体的ESI质谱证据,可以深入了解吡咯烷基催化剂的机理。使用质谱分析反应中间体提供了吡咯烷催化剂在通过氢键活化硝基烯烃中也起作用的证据。