Acid catalyzed stereoselective rearrangement and dimerization of flavenes: synthesis of dependensin

A Practical Access to Highly Enantiomerically Pure Flavanones by Catalytic Asymmetric Transfer Hydrogenation

“…Our approach to ( S )‐ and ( R )‐glabrol ( 4 ) is shown in Scheme . Racemic 4 26 was prepared from commercially available liquiritigenin ( rac ‐ 11 )27 by formation of the double isoprenyl ether through reaction with carbonate 13 28 followed by a highly regioselective europium(III)‐catalyzed4, 29 twofold Claisen rearrangement preferably under microwave irradiation. Formation of diacetate rac ‐ 14 set the stage for the crucial asymmetric transfer hydrogenation, which proceeded with excellent enantioselectivity using catalyst III .…”

Ein praktischer Zugang zu hoch enantiomerenreinen Flavanonen durch katalytische asymmetrische Transferhydrierung

“…Unser Zugang zu ( S )‐ und ( R )‐Glabrol ( 4 ) ist in Schema gezeigt. Racemisches 4 26 wurde aus kommerziell erhältlichem Liquiritigenin ( rac ‐ 11 )27 durch doppelte Isoprenyletherbildung mit dem Carbonat 13 28 mit nachfolgender, hoch regioselektiver Europium(III)‐katalysierter4, 29 zweifacher Claisen‐Umlagerung vorzugsweise unter Mikrowellenbestrahlung hergestellt. Die Bildung des Diacetats rac ‐ 14 bereitete die entscheidende asymmetrische Transferhydrierung vor, die unter Nutzung des Katalysators III mit exzellenter Enantioselektivität verlief.…”

Synthesis and Anti-Tumor Activity of Novel Aminomethylated Derivatives of Isoliquiritigenin

“…Therefore, it is very significant for scientists to screen active compounds from plants and synthesized new derivatives with similar molecular structures as potential anti-tumor drugs or pro-drugs [1][2][3]. As a common active ingredient of many Chinese herbal medicines [4,5], flavonoids reveal little side effects in clinical research [6,7]. Among numerous flavonoids, isoliquiritigenin (ISL) attracted the attention of many scientists.…”