通过使用双功能奎尼丁衍生的尿素作为催化剂,实现了3-乙酰基-2 H-色烯-2-酮和靛红的不对称醛醇反应。以良好的产率和高对映选择性获得了相应的含有 2 H -chromen-2-one 部分的3-羟基羟吲哚衍生物。当 ( Z )-乙基 2-亚苄基乙酰乙酸乙酯用作底物时,由于双键在反应条件下异构化,得到两种非对映异构体(Z和E)的混合物。
Asymmetric chroman synthesis via an intramolecular oxy-Michael addition by bifunctional organocatalysts
作者:Ryota Miyaji、Keisuke Asano、Seijiro Matsubara
DOI:10.1039/c3ob41938j
日期:——
organocatalysts facilitate the catalytic asymmetric synthesis of chroman derivatives via an intramolecular oxy-Michael addition reaction. Phenol derivatives bearing an easily available (E)-α,β-unsaturated ketone or a thioester moiety are useful substrates for the title transformation. This method represents a facile synthesis of various optically active 2-substituted chromans in high yield.
An efficient enantioselective aryloxylation of cyclic β-ketoesters with a selection of substituted o-quinones catalyzed by a bifunctional cinchona alkaloid derivative, giving entry to tricyclic dioxin adducts with high enantio- and diastereoselectivity, is described. aryloxylation - quinones - β-ketoester - organocatalysis - dioxins
Asymmetric Indoline Synthesis via Intramolecular Aza-Michael Addition Mediated by Bifunctional Organocatalysts
作者:Ryota Miyaji、Keisuke Asano、Seijiro Matsubara
DOI:10.1021/ol401538b
日期:2013.7.19
A novel method for the asymmetric synthesis of 2-substituted indolines, employing bifunctional amino(thio)urea catalysts, was developed. The reaction proceeded via an intramolecular aza-Michael addition mediated by activation through hydrogen bonding. The catalytic process was shown to be highly versatile and applicable to a wide range of substrates due to the flexible catalytic mechanism utilizing a noncovalent interaction.
Bifunctional Organocatalysts for the Enantioselective Synthesis of Axially Chiral Isoquinoline <i>N</i>-Oxides
作者:Ryota Miyaji、Keisuke Asano、Seijiro Matsubara
DOI:10.1021/jacs.5b04151
日期:2015.6.3
Bifunctional catalysts bearing amino and urea functional groups have been applied for a novel, highly enantioselective synthesis of axially chiral isoquinoline N-oxides, which are promising chiral ligands or organocatalysts in organic synthesis. This is the first example of highly enantioselective synthesis of axially chiral biaryls by bifunctional organocatalysts. Good-to-excellent enantioselectivities were obtained with a range of substrates.