Synthesis of Diverse Oxa‐Carbocycle‐Annulated Flavones Using the Combined Claisen Rearrangement and Ring‐Closing Metathesis

Abstract

A simple and efficient route for the synthesis of oxepine‐, oxocine‐, oxepinone‐, and dioxocine‐angularly annulated flavone skeletons has been developed. The combined Claisen rearrangement and the ring‐closing metathesis are used as key steps for the construction of C7/C8–C6–C6 tricyclic core structures.

Exciting progress in the transition metal‐catalyzed synthesis of oxepines, benzoxepines, dibenzoxepines, and other derivatives

“…Gogula and Yerrabelly in 2016 synthesized a library of potentially bioactive oxepinoflavones via Claisen rearrangement and the ring‐closing metathesis using Grubbs' catalysts (Schemes 56–58). [ 12 ]…”

“…Gogula and Yerrabelly in 2016 synthesized a library of potentially bioactive oxepinoflavones via Claisen rearrangement and the ring-closing metathesis using Grubbs' catalysts (Schemes 56-58). [12] da Rocha et al in 2014 reported the synthesis of the oxepin-1,4-naphthoquinones 305 through the C-and Oalkylation of lawsone 302 with allyl bromide 179 followed by ring-closing metathesis using Grubbs' catalyst (Scheme 59). [96] Several strategies have been reported for the synthesis of these type compounds, but there are various disadvantages such as low reaction yields and production of byproducts.…”

“…These compounds were found to have potential uses in pharmaceuticals [ 4–6 ] and also in polymers. The number of biological properties of these compounds is containing anti‐inflammatory, [ 7–9 ] antiproliferative, [ 10 ] antitumor [ 1 ] and anticancer, [ 10 ] antiplasmodial, [ 11 ] antihelminthic activity, [ 12 ] antibiotic activity, [ 13–16 ] antiestrogenic, [ 17 ] analgesic, [ 18 ] antipsychotic, [ 9,19–21 ] angiotensin II receptor antagonistic, [ 22 ] antioxidant, [ 23 ] antimycobacterial, [ 24 ] and antiapoptosis. [ 25 ] Some of oxepine, benzoxepine, and dibenzoxepine derivatives have been synthesized by Tishchenko‐like reaction, [ 26 ] Friedel–Crafts acylation reactions, [ 27 ] Suzuki coupling, [ 28 ] and Catellani reaction.…”