Pentacyclic coumarin-based blue emitters – the case of bifunctional nucleophilic behavior of amidines
作者:Yevgen M. Poronik、Daniel T. Gryko
DOI:10.1039/c4cc01106f
日期:——
Esters of coumarin-3-carboxylic acids undergo addition to DBU and DBN leading to the formation of a 6-membered ring.
香豆素-3-羧酸酯经DBU和DBN加成反应,形成一个6元环。
Role of Configuration at C6 in Catalytic Activity of <scp>l</scp>-Proline-Derived Bifunctional Organocatalysts
作者:Hui Jin、Soo Min Cho、Juyeol Lee、Do Hyun Ryu
DOI:10.1021/acs.orglett.7b01000
日期:2017.5.5
chiral bifunctional (thio)urea organocatalysts epi-PTU and epi-PU were newly synthesized, and their catalytic performances were compared with their C6 epimeric catalysts PTU and PU in various Michael reactions of nitrostyrene in terms of reactivities and stereoselectivities. The experimental results indicate that a proper relative stereochemistry at C2 and C6 in l-proline-derived bifunctional organocatalysts
Synthesis of 3-Arylated 3,4-Dihydrocoumarins: Combining Continuous Flow Hydrogenation with Laccase-Catalysed Oxidation
作者:Sanel Suljić、Jörg Pietruszka
DOI:10.1002/adsc.201300990
日期:2014.3.24
laccase‐catalysed oxidation/Michael addition sequence is applied using commercially available laccase from Agaricus bisporus. 3,4‐Dihydrocoumarins were obtained in a rapid and facile two‐step sequence starting from salicylaldehydes: The corresponding coumarins were synthesised through a Knoevenagel condensation in up to 83% yield followed by a quantitative reduction performed in a flow system. Combining the reductive
Asymmetric hydrogenation of esters through homogeneous catalysis is a significantly important transformation in organic synthesis. The systems developed so far mainly focused on chiral iridium and ruthenium catalysts, which required a base to facilitate the activity. Herein, we present a palladium-catalyzed asymmetric hydrogenation of lactones under base-free conditions through dynamic kinetic resolution
Construction of 3,4-Dihydrocoumarin Derivatives with Adjacent Quaternary and Tertiary Stereocenters: Organocatalytic Asymmetric Michael Addition of 2-Oxochroman-3-carboxylate Esters to<i>trans</i>-<i>β</i>-Nitroolefins
作者:Hui Jin、Soo Min Cho、Geum-Sook Hwang、Do Hyun Ryu
DOI:10.1002/adsc.201600825
日期:2017.1.4
An asymmetric Michael addition of 2‐oxochroman‐3‐carboxylate esters to trans‐β‐nitroolefins is described. This strategy can give direct access to dihydrocoumarin derivatives bearing adjacentquaternary and tertiarystereocenters with up to >99% yield, >20:1 dr, and >99% ee. The adduct was further transformed to a spiro‐dihydrocoumarin compound in three steps with good yield.