Catalytic Enantioselective Synthesis of Flavanones and Chromanones
摘要:
The enantioselective synthesis of flavanones and chromanones is described. Bifunctional thiourea catalysts promote an asymmetric oxo-conjugate addition to a beta-ketoester alkylidene in high yields with excellent enantioselectivity (80-94% ee) for aryl and alkyl substrates. Decarboxylation of the beta-ketoester proceeds smoothly in a one-pot procedure to afford the enantioenriched flavanones and chromanones.
Catalytic asymmetric conjugate addition of Grignard reagents to chromones
作者:Carlos Vila、Valentín Hornillos、Martín Fañanás-Mastral、Ben L. Feringa
DOI:10.1039/c3cc43105c
日期:——
highly regio- and enantioselective copper catalysed direct conjugateaddition of Grignard reagents to chromones has been developed taking advantage of the reduced reactivity of the resulting magnesium enolates. This methodology tolerates a broad scope of alkyl Grignards including secondary alkyl magnesium reagents as well as functionalised chromones.
Chiral chromanols and their derivatives have been synthesized via a RuPHOX–Ru catalyzedasymmetrichydrogenation of chromones in high yields, >20 : 1 drs and with up to 99.9% ee. Control experiments show that the reaction undergoes two sequential asymmetrichydrogenation steps of the CC and CO double bonds. The reaction could be performed on a gram-scale with a relatively low catalyst loading (up to
通过RuPHOX-Ru催化色酮的不对称氢化,以高产率,> 20:1 drs和最高99.9%ee合成了手性苯甲酚及其衍生物。对照实验表明,该反应经历了C C和C O双键的两个连续的不对称氢化步骤。该反应可以以克级进行,具有相对较低的催化剂负载量(最高1000 S / C),并且所得产物可以转化为几种生物活性化合物。
A Facile Enantioselective Alkynylation of Chromones
作者:Lindsey G. DeRatt、Mukesh Pappoppula、Aaron Aponick
DOI:10.1002/anie.201902405
日期:2019.6.17
The first catalytic enantioselective alkynylation of chromones is reported. In this process, chromones are silylated to form silyloxybenzopyrylium ions that lead to silyl enol ethers after Cu‐catalyzed alkyne addition using StackPhos as a ligand. The outcome of the reaction is impacted by distal ligand substituents with differing electronic character and it was found that successful reactions could
Copper Bis(oxazoline)‐Catalyzed Enantioselective Alkynylation of Benzopyrylium Ions
作者:Yong Guan、Jonathan W. Attard、Anita E. Mattson
DOI:10.1002/chem.201904822
日期:2020.2.6
stereocontrolled construction of biologically relevant chromanones and tetrahydroxanthones has been achieved through the addition of alkynes to benzopyrylium trilfates under the influence of copper bis(oxazoline) catalysis. Excellent levels of enantiocontrol (63-98 % ee) are achieved in the addition of a variety of alkynes to an array of chromenones with a hydrogen in the 2-position. Promising levels of