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

The regiodivergent catalytic dehydrogenative cross-coupling reactions at both sp(2) and sp(3) hybridized carbons of aromatic compounds are particularly challenging. Herein, we report the finding of transient directing group controlled regiodivergent C(sp(3))-C(sp(2)) and C(sp(2))-C(sp(2)) cross-coupling in the o-methyl benzaldehyde frameworks. Catalyzed by palladium, using K2S2O8 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.

Automated summary

This study reports the regioselective cross-coupling reactions in the o-methyl benzaldehyde frameworks using palladium catalysis, K2S2O8 or [F+] reagents as oxidants, and unactivated arenes as substrates/solvents. The regiospecificity is controlled by [5,6]-fused or [6,5]-fused palladacycle intermediates formed from Pd-chelation with specific transient directing groups and C-H activations.