SELECTIVE ARYL RADICAL TRANSFERS INTO N-HETEROAROMATICS FROM DIARYLIODONOIUM SALTS WITH TRIMETHOXYBENZENE AUXILIARY

摘要

We have found that a series of trimethoxybenzene-based diaryl-iodonium(III) salts I (ArI+Ar'X-, where Ar = various aryl groups, Ar' = 2,4,6-trimethoxyphenyl, X- = counterion) can exclusively cause Ar-transfers during the base-induced radical couplings with N-heteroaromatic compounds 1 by working the trimethoxybenzene ring (Ar') as an inert coupling auxiliary. By the treatment with N-heteroaromatics 1 as the solvent, the metal-free arylations utilizing the specific salts I initiated by solid NaOH upon heating selectively produced the corresponding biaryls 2 in good yields without the formation of the trimethoxybenzene (Ar') coupling product.