关键词: 芳磺酸酯, 芳基烷基醚, 二芳基醚, 化学键, 酚, 醇

Aryl alkyl ethers and diaryl ethers represent ubiquitous structural motifs in natural products, medicinally relevant compounds, biologically active compounds, agrochemicals and organic materials, and they are also useful building blocks in organic synthesis. Therefore, many transformations have been reported for the synthesis of these two kinds of compounds. Among these versatile methods, transition-metal-free approaches using different reagents as starting materials have been developed as promising and alternative protocols. Although one example for transition-metal-catalyzed transformation of arenesulfonates into aryl alkyl ethers and diaryl ethers has been reported, there are no reports about the formation of aryl ethers utilizing arenesulfonates as starting materials via a transition-metal-free protocol, and existing methods for providing sterically hindered ortho-substituted diaryl ethers using electrophiles substituted by electron-deficient groups, particularly by a bulky one at the ortho-position as starting materials are very rare. We will report a K₂CO₃-mediated method for the synthesis of aryl alkyl ethers using arenesulfonates as starting materials via two alternative paths. One path is the cross-coupling of aryl arenesulfonates with alcohols through their S―O bond cleavage, and the other uses the reactions of alkyl arenesulfonates with phenols via their C―O bond cleavage. Additionally, we also report the K₃PO₄-promoted preparation of bulky ortho-substituted diaryl ethers via the C―S bond cleavage of aryl arenesulfonates or arenesulfonyl chlorides bearing electron-withdrawing groups at 2-, 2,4- or 2,6-position of the phenyl ring in the presence of phenols, respectively. General procedure for the reactions of aryl arenesulfonates with various alcohols: to an oven-dried glass tube, aryl arenesulfonate 1 (0.2 mmol), K₂CO₃ (2 equiv.) and 0.5 mL alcohol 2 were added in turn. The reaction system was then stirred at 65 ℃ until the aryl arenesulfonate 1 was completely consumed as determined by thin layer chromatography. Finally, the reaction mixture was purified by silica gel column chromatography to afford the desired product 3. General procedure for the reactions of aryl o-substituted arenesulphonates with the corresponding phenols: to an oven-dried glass tube, aryl o-substituted arenesulfonate 7 (0.2 mmol), K₃PO₄ (3 equiv.), the corresponding phenol 5 (1.2 equiv.) and 1.0 mL toluene were added in turn. The reaction system was then stirred at 100 ℃ until the reaction was over as determined by TLC. Finally, the reaction mixture was purified by silica gel column chromatography to afford the desired product 8.

Key words: arenesulphonate, aryl alkyl ether, diaryl ether, chemical bond, phenol, alcohol