O-Annulation Leading to Five-, Six-, and Seven-Membered Cyclic Diaryl Ethers Involving C-H Cleavage

Cyclic diaryl ethers are present in multiple natural compounds, organic pollutants as well as in π-conjugated organic molecular materials. This short review aims at overviewing the main synthetic advances in the O-annulation methods for preparing five-, six-, and seven-membered rings through C-H cleavage. 1 Introduction 2 Five-Membered Rings: The Dibenzofuran (DBF) Motif 2.1 Palladium-Catalysed C-H Activation 2.2 Copper-Catalysed C-H Activation 2.3 Non-CH Activation Oxidant-Mediated Cyclisation 2.4 Light-Mediated Cyclisation 2.5 Acid-catalysed C-O Cleavage/C-O Formation 3 Six-Membered Rings: DBX, PXX, Xanthone, and Their Derivatives 3.1 Dibenzoxanthene (DBX) 3.2 Peri -Xanthenoxanthene (PXX) 3.3 Xanthones 3.4 Miscellaneous 4 Seven-Membered Rings: Cularine 5 Conclusion.