Dynamic resolution of N-alkyl-2-lithiopyrrolidines with the chiral ligand (−)-sparteine
作者:Iain Coldham、Samuel Dufour、Thomas F.N. Haxell、Graham P. Vennall
DOI:10.1016/j.tet.2005.01.096
日期:2005.3
dynamic resolution in the presence of the chiral ligand (−)-sparteine. Good yields of the electrophile-quenched products were obtained with enantiomer ratios up to 85:15 using branched N-alkyl derivatives. The major product was shown to have the opposite absolute configuration compared with that obtained in the asymmetric deprotonation of N-Boc-pyrrolidine with (−)-sparteine. The enantioselectivity arises
制备了具有不同N-烷基取代基的2-硫代吡咯烷的选择物,并在手性配体(-)-天冬氨酸存在的情况下测试了它们的动态拆分。使用支化的N-烷基衍生物,对映体比率高达85:15,得到了高亲电猝灭产物的收率。与N -Boc-吡咯烷与(-)-天冬氨酸的不对称去质子化反应相比,显示出主要产物具有相反的绝对构型。对映选择性来自动态热力学拆分,其中次要非对映异构体与亲电子试剂反应更快。