Novel thiophosphonodiamides as efficient hydrogen bond donor catalysts in tandem Michael addition–cyclization of malononitrile and 2-(E)-2-nitrovinylphenols
摘要:
From L-amino acid, three chiral thiophosphonodiamides were prepared as new hydrogen bond donor organocatalysts. Under the mediation of the catalyst derived from L-valine, a tandem Michael addition/cyclization reaction between (E)-2-(2-nitrovinyl)phenols and malononitrile proceeds smoothly, giving pharmaceutically valuable 2-amino-4H-chromene-3-carbonitriles in high yields with 66-95% ee within 2 h. (C) 2013 Elsevier Ltd. All rights reserved.
Enantioselective synthesis of 2-amino-4-(nitromethyl)-4<i>H</i>-chromene-3-carbonitriles from 2-iminochromenes
作者:Gamze Koz、Omer Koz、Necdet Coskun
DOI:10.1080/00397911.2016.1177728
日期:2016.5.18
ABSTRACT A series of medicinally important 2-amino-4-(nitromethyl)-4H-chromene-3-carbonitriles were synthesized using enantioselective conjugateaddition of nitromethane to 2-iminochromenes. The reactions were performed using L8-Cu (II) catalytic system and moderate to good enantioselectivities (62–88%) and yields (66–96%) were obtained. GRAPHICAL ABSTRACT
摘要 利用硝基甲烷与 2-亚氨基色烯的对映选择性共轭加成,合成了一系列具有药用价值的 2-氨基-4-(硝基甲基)-4H-色烯-3-腈。使用 L8-Cu (II) 催化体系进行反应,获得了中等至良好的对映选择性 (62-88%) 和产率 (66-96%)。图形概要
Chiral bifunctional squaramide catalyzed asymmetric tandem Michael-cyclization reaction: efficient synthesis of optically active 2-amino-4H-chromene-3-carbonitrile derivatives
We have developed an efficient bifunctional squaramide catalyst for the asymmetric tandem Michael addition-cyclization of malononitrile to functionalized nitroolefins. This organocatalytic asymmetric reaction provides convenient and valuable access to highly functionalized 2-amino-4H-chromene derivatives, which possess important biological activities, in good yields with moderate to high enantioselectivities (up to 95% ee). (C) 2013 Elsevier Ltd. All rights reserved.
C3-Symmetric cinchonine-squaramide as a recyclable efficient organocatalyst for tandem Michael addition–cyclisation of malononitrile and nitrovinylphenols
The tandem enantioselective Michael addition/cyclisation reaction of malononitrile and nitrovinylphenols was catalysed by a recoverable C-3-symmetric cinchonine-squaramide organocatalyst la to afford the 2-amino-4H-chromene-3-carbonitrile derivatives in excellent yields (up to 95%) and with excellent enantioselectivities (up to 98% ee) under mild reaction conditions. Furthermore, this catalyst can be easily recovered four times without loss in activity or enantioselectivity. (C) 2016 Elsevier Ltd. All rights reserved.