College of Chemistry, Beijing Normal University , Beijing 100875, China.
J Org Chem. 2018 Feb 16;83(4):1913-1923. doi: 10.1021/acs.joc.7b02849. Epub 2018 Jan 26.
The cascade catalysis involving N-heterocyclic carbene (NHC) and palladium/ligand was demonstrated. In the presence of a triazolium salt, palladium catalyst, and base, the reaction of 3-(2-formylphenoxy)propenoates and allylic esters proceeded efficiently under mild conditions to afford 2-allylbenzofuran-3-one-2-acetates in moderated to good yields. An asymmetric cascade catalysis was achieved when (R)-BINAP was employed as a chiral ligand, producing enantiomerically enriched 2,2-disubstitiuted benzofuran-3-one derivatives with an ee up to 81%.
展示了涉及 N-杂环卡宾（NHC）和钯/配体的级联催化。在三唑鎓盐、钯催化剂和碱的存在下，3-(2-甲酰基苯氧基)丙烯酸酯和烯丙基酯在温和条件下反应，以中等至良好的收率得到 2-烯丙基苯并呋喃-3-酮-2-乙酸酯。当（R）-BINAP 用作手性配体时，实现了不对称级联催化，生成对映体富集的 2,2-二取代苯并呋喃-3-酮衍生物，ee 值高达 81%。
