Isoaurostatin: total synthesis and structural revision

Metal‐Free Tandem Rearrangement/Lactonization: Access to 3,3‐Disubstituted Benzofuran‐2‐(3H)‐ones

“…Benzofuran‐2‐(3 H )‐ones are interesting oxygen‐containing heterocycles that are found in several biologically active natural products such as yuccaols, rosmadial, (−)‐fumimycin, and abiesinol A (Figure ). Benzofuran‐2‐(3 H )‐ones can also be used as building blocks for the synthesis of sesquiterpenes such as aplysins and isolaurinterol, and the flavonoid‐related aurones . Due to their quaternary carbon at the C‐3 position, 3,3‐disubstituted benzofuranones represent challenging synthetic targets.…”

“…Benzofuran-2-(3H)ones can also be used as building blocks for the synthesis of sesquiterpenes such as aplysins and isolaurinterol, [5] and the flavonoid-related aurones. [6] Due to their quaternary carbon at the C-3 position, 3,3-disubstituted benzofuranones represent challenging synthetic targets.Arecent popular approach towards such structures is the late-stage functionalization of benzofuranones,e ither metal-catalyzed or promoted by organocatalysts. [7] Methods for the synthesis of the lactone framework have also been investigated, such as metalcatalyzed CÀHa ctivation/CÀOb ond formations, [8] tandem Friedel-Crafts/lactonization, [9] Reppe-type cyclocarbonylation, [10] and the condensation of phenol derivatives.…”

Metallfreie Tandem‐Umlagerung/Lactonisierung: Zugang zu 3,3‐disubstituierten Benzofuran‐2‐(3H)‐onen

“…Benzofuran-2-(3H)-one kçnnen auch als Bausteine fürd ie Synthese von Sesquiterpenen wie Aplysine und Isolaurinterol [5] und den mit Flavonoiden verwandten Auronen verwendet werden. [6] Aufgrund ihres quartären Kohlenstoffatoms in C-3-Position sind 3,3-disubstituierte Benzofuranone anspruchsvolle Syntheseziele.Ein neuer,populärer Ansatz zur Synthese solcher Strukturen ist die spätere Funktionalisierung von Benzofuranonen, die entweder metallkatalysiert oder mithilfe von Organokatalysatoren erfolgen kann. [7] Es wurden auch Methoden zur Synthese des Lactongerüsts untersucht, z.…”

“…Benzofuran‐2‐(3 H )‐one sind interessante sauerstoffhaltige Heterocyclen, die in mehreren biologisch aktiven Naturstoffen wie in Yuccaolen, Rosmadial, (−)‐Fumimycin und Abiesinol A vorkommen (Abbildung ). Benzofuran‐2‐(3 H )‐one können auch als Bausteine für die Synthese von Sesquiterpenen wie Aplysine und Isolaurinterol und den mit Flavonoiden verwandten Auronen verwendet werden . Aufgrund ihres quartären Kohlenstoffatoms in C‐3‐Position sind 3,3‐disubstituierte Benzofuranone anspruchsvolle Syntheseziele.…”

Antitumor agents. 271: Total synthesis and evaluation of brazilein and analogs as anti-inflammatory and cytotoxic agents

“…Treatment of 5 with iodomethane in the presence of K 2 CO 3 /acetone gave 6 (60%). Acid catalyzed17 condensation of 6 with 3,4-dimethoxybenzaldehyde afforded 7 (78%). Epoxidation of 7 with alkaline hydrogen peroxide gave epoxy ketone 8 (90%), which was reduced to the diol 9 (89%) with LiAlH 4 3.…”