Regiodivergent CDC reactions of aromatic aldehydes with unactivated arenes controlled by transient directing strategy.

The regiodivergent catalytic dehydrogenative cross-coupling reactions at both sp and sp hybridized carbons of aromatic compounds are particularly challenging. Herein, we report the finding of transient directing group controlled regiodivergent C(sp)-C(sp) and C(sp)-C(sp) cross-coupling in the -methyl benzaldehyde frameworks. Catalyzed by palladium, using KSO or [F] reagents as by-standing oxidants and unactivated arenes as substrates/solvents, various benzyl benzaldehydes or phenyl benzaldehydes were prepared. A mechanism study indicated that the regiospecificity is dominated by the [5,6]-fused palladacycle or [6,5]-fused palladacycle intermediates, which are generated from Pd-chelation with specified transient directing groups and further C-H activations.