Metal-free direct biaryl coupling reaction of heteroaromatic compounds via iodonium intermediate.

Biaryl compounds are versatile building blocks in the synthesis of natural products, pharmaceuticals, agricultural chemicals and π-conjugated organic materials. This review describes a recent progress for the biaryl cross-coupling reaction of heteroaromatic compounds using hypervalent iodine reagent. Our novel biaryl coupling reaction is a unique method for constructing various heteroaromatic biaryls without use of transition metal catalysts. From mechanistic point of view, the coupling reaction was realized through stable iodine intermediate generated from heteroaroamatic compound and iodine (III) reagent.