Dieter R Karl, Guo Fenghai
Department of Chemistry, Hunter Laboratory, Clemson University, Clemson, South Carolina 29634-0973, USA.
J Org Chem. 2009 May 15;74(10):3843-8. doi: 10.1021/jo900327q.
N-carbamoyl-4-pyridones undergo conjugate addition reactions with organocuprates and organozincates to afford 2-substituted-2,3-dihydro-4-pyridones providing a direct synthetic approach to substituted piperidines and piperidones. Good to excellent yields of conjugate adducts are achieved with lithium dialkylcuprates, alkylcyanocuprates, RLi/CuCN (0.3 equiv), and trialkylzincates with copper catalysis. Copper catalysis in the conjugate addition of Grignard reagents affords modest yields of conjugate adducts. An enantioenriched phosphoramidite ligand promotes the copper catalyzed conjugate addition of Et(2)Zn to a N-carbamoyl-4-pyridone with an er of 91.5:8.5.
N-氨基甲酰基-4-吡啶酮与有机铜酸盐和有机锌酸盐发生共轭加成反应，生成2-取代的2,3-二氢-4-吡啶酮，为取代哌啶和哌啶酮提供了一种直接的合成方法。使用二烷基铜酸锂、烷基氰基铜酸盐、RLi/CuCN（0.3当量）以及在铜催化下的三烷基锌酸盐，可实现共轭加合物的良好至优异产率。在格氏试剂的共轭加成反应中，铜催化只能得到中等产率的共轭加合物。一种对映体富集的亚磷酰胺配体可促进铜催化的Et(2)Zn与N-氨基甲酰基-4-吡啶酮的共轭加成反应，对映体比例为91.5:8.5。
