Pd-Catalyzed C(sp 3 )-H Biarylation via Transient Directing Group Strategy.

Here, we describe a highly selective Pd-catalyzed C(sp ³ )-H biarylation of 2-methylbenzaldehydes using cyclic diaryliodonium salts as arylation reagents. The key strategy is the employment of tert -leucine as a bidentate transient directing group for the proximity-driven metalation to achieve reactivity and selectivity in C-H activation. Various functionalized biaryls bearing both aldehyde and iodine functional groups were prepared successfully, which could be further transformed into a wide range of compounds with potential applications in pharmaceutical chemistry and materials science.