Rhodium-catalysed enantioselective synthesis of 4-arylchroman-2-ones
作者:Joseph C. Allen、Gabriele Kociok-Köhn、Christopher G. Frost
DOI:10.1039/c1ob06586f
日期:——
The rhodium-catalysed enantioselective 1,4-addition of organoboron reagents to arylidene Meldrum's acids as acceptors, allows convenient access to 4-arylchroman-2-ones with good to excellent levels of enantioselectivity. The use of silyl-protected dioxaborinanes as donors was found to be advantageous to achieving good yields of product under anhydrous conditions.
A palladium-catalyzed enantioselective hydroesterification of alkenylphenols with phenyl formate. A facile approach to optically active dihydrocoumarins
作者:Jingfu Li、Wenju Chang、Wenlong Ren、Wei Liu、Haining Wang、Yian Shi
DOI:10.1039/c5ob01431j
日期:——
An effective palladium-catalyzed enantioselective hydroesterification of alkenylphenols with phenyl formate as a CO source is described.
描述了一种有效的钯催化的对映选择性氢甲酯化反应,该反应以烯基酚和苯甲酸酯作为一氧化碳源。
Organic Solvent‐free Asymmetric 1,4‐Addition in Liquid‐ or Solid‐State using Conventional Stirring Catalyzed by a Chiral Rhodium Complex Developed as a Homogeneous Catalyst
Organic solvent‐free asymmetric 1,4‐addition of arylboronicacids to enone substrates was performed by using a chiral rhodium complex catalyst developed as a homogeneous catalyst. Reactions catalyzed by [RhOH(cod)]2 with chiral diphosphine ligands in liquid‐ or solid‐state proceeded to give chiral 1,4‐adducts in high yield with enantioselectivities up to ca. 100 % ee by conventional stirring without
Palladium and a simple chiral amine are used as co‐catalysts for the enantioselective conjugate addition of aryl boronic acids to α,β‐unsaturated aldehydes (see scheme). The synthetic utility of this co‐catalyzed reaction was demonstrated in the short total syntheses of (R)‐(−)‐curcumene and 4‐aryl‐2‐ones.
carried out at 0–25 °C in the presence of a dicationic palladium(II) catalyst, [Pd(S,S-chiraphos)(PhCN)2](SbF6)2. Addition of a silver salt such as silvertetrafluoroborate [AgBF4] or silver hexafluoroantimonate [AgSbF6] (5–10 mol %) was effective to achieve high enantioselectivities at low temperatures (92–99 % ee) and to reduce the catalyst loading to 0.05 mol %. The protocol provided a simple access to