An Attractive and Comprehensive Review on C-O Bond Formation: Nanomagnetic Recoverable Catalysts to Access Diaryl Ethers via C-O Cross-coupling Reactions

: The simple separation of magnetic nanocatalysts from the reaction mixture using only an external magnet caused a huge revolution in catalysis, particularly in organic synthesis. Diaryl ethers (compounds containing (Ar-O-Ar linkages) are one of the most important and prominent compounds and are widely found in natural products and pharmaceutical and biological molecules. The C-O cross-coupling or O-arylation reactions of aryl halides with aromatic alcohols, especially phenols, is an important and straightforward strategy for the preparation of diaryl ethers. Due to the high importance of diaryl ethers in the pharmaceutical, chemical and medical fields, many efforts have been made for the synthesis of diaryl ethers through C-O cross-coupling aryl halides with aromatic alcohols, especially phenols based on using non-magnetic reusable catalysts. In this review, we carefully reviewed the synthesis of diaryl ethers and discussed the reaction conditions and product yields in each method.