Coupling Catalytic Alkene Hydroacylation and α-Arylation: Enantioselective Synthesis of Heterocyclic Ketones with α-Chiral Quaternary Stereocenters
作者:Avipsa Ghosh、James A. Walker、Arkady Ellern、Levi M. Stanley
DOI:10.1021/acscatal.6b00365
日期:2016.4.1
strategy that combines alkene hydroacylation and enantioselective α-(hetero)arylation reactions to form a wide variety of nitrogen-containing heterocyclic ketones bearing α-chiral quaternary stereogenic centers. Exo-selective, intramolecular Ni-catalyzed hydroacylations of N-homoallylindole- and N-homoallylpyrrole-2-carboxaldehydes form α-substituted six-membered heterocyclic ketones in up to 95% yield
我们报告了一种策略,结合了烯烃加氢酰化和对映选择性的α-(杂)芳基化反应,形成了多种含α-手性季立体中心的含氮杂环酮。N-烯丙基烯丙基和N-烯丙基吡咯-2-羧酸的分子外选择性Ni催化加氢酰化反应可形成高达95%产率的α-取代的六元杂环酮,而N杂环卡宾(NHC)催化N的加氢酰化反应-烯丙基-和N-烯丙基吡咯-2-羧醛形成α-取代的五元杂环酮,产率高达99%。Ni和NHC催化的加氢酰化反应的外消旋五元和六元产物易于通过对映选择性Ni催化的α-芳基化和α-杂芳基化反应转变为含有α-手性季立体中心的杂环酮。通过烯烃加氢酰化和α-(杂)芳基化反应的组合形成的手性,非外消旋产物,以中等至高产率(44–99%)形成,并具有出色的对映选择性(通常> 95%ee)。Ni催化的α-(杂)芳基化反应的前催化剂的身份由α-取代的杂环酮起始原料的身份决定。2和(R)-BINAP或(R)-DIFLUORPHOS。的五