Asymmetric construction of quaternary stereocenters by magnesium catalysed direct amination of β-ketoesters using in situ generated nitrosocarbonyl compounds as nitrogen sources
Ethynyl-1,2-benziodoxol-3(1 H)-one (EBX): An Exceptional Reagent for the Ethynylation of Keto, Cyano, and Nitro Esters
作者:Davinia Fernández González、Jonathan P. Brand、Jérôme Waser
DOI:10.1002/chem.201001539
日期:2010.8.16
Hot alkyne! The in situ generation of ethynyl‐1,2‐benziodoxol‐3(1H)‐one (EBX) from a silyl‐protected reagent by using TBAF is reported. EBX displayed exceptional acetylene transfer ability onto stabilizedenolates (see scheme), even at −78 °C. The mild reaction conditions allowed the first ethynylation reactions of linear keto, cyano, and nitro esters in high yields to give all‐carbon quaternary centers
Organocatalytic Asymmetric Direct α-Alkynylation of Cyclic β-Ketoesters
作者:Thomas B. Poulsen、Luca Bernardi、José Alemán、Jacob Overgaard、Karl Anker Jørgensen
DOI:10.1021/ja067289q
日期:2007.1.1
The first organocatalyticenantioselective direct α-alkynylation of β-ketoesters and 3-acyl oxindoles is described. It is demonstrated that activated β-halo-alkynes undergo nucleophilic acetylenic substitution catalyzed by chiral phase-transfer compounds to afford the alkynylated products in high yields and excellent enantioselectivities. The potential of the reaction is first demonstrated for various
Asymmetric construction of quaternary stereocenters by magnesium catalysed direct amination of β-ketoesters using in situ generated nitrosocarbonyl compounds as nitrogen sources
作者:Biplab Maji、Mahiuddin Baidya、Hisashi Yamamoto
DOI:10.1039/c4sc01272k
日期:——
An oxophilic magnesium salt in combination with a chiral N,N′-dioxide ligand switches the chemoselectivity of an ambident nitrosocarbonyl species to nitrogen for the highly enantioselective α-amination of β-ketoesters.