Copper‐Catalyzed Selective N‐Arylation of Oxadiazolones by Diaryliodonium Salts

Here, we report the method for copper‐catalyzed N‐arylation of diverse oxadiazolones by diaryliodonium salts under mild conditions in high yields (up to 92%) using available CuI as a catalyst. The developed method allows utilizing both symmetric and unsymmetric diaryliodonium salts bearing auxiliary groups such as 2,4,6‐trimethoxyphenyl (TMP). We found that the steric effects in aryl moieties determined the chemoselectivity of N‐ and O‐arylation of the 1,2,4‐oxadiazol‐5(4H)‐ones. Mesityl‐substituted diaryliodonium salts demonstrated the high potential as a selective arylation reagent. The structural study suggests that steric accessibility of N‐atom in 1,2,4‐oxadiazol‐5(4H)‐ones impact to arylation with sterically hindered diaryliodonium salts. The synthetic application of proposed method was also demonstrated on selective arylation of 1,3,4‐oxadiazol‐2(3H)‐ones and 1,2,4‐oxadiazole‐5‐thiol.

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