ortho -C(sp 3 )-H arylation of aromatic aldehydes using 2-amino- N -methyl-acetamide as a L,L-type transient directing group.

Pd-catalyzed ortho -C(sp 3 )-H arylation of aromatic aldehydes using 2-amino- N -methyl-acetamide as a simple, efficient and commercially available L,L-type transient directing group (TDG) is reported. The reaction exhibited excellent substrate compatibility and generated the desired products in moderate-to-high yields up to 78%. Further acid-catalyzed cyclization and dehydrative aromatization were also tested, and furnished some polycyclic aromatic hydrocarbons with excellent yields up to 96%. The X-ray crystal structure of a 2-methylbenzaldehyde ortho -C(sp 3 )-H palladation intermediate was obtained. Then, a plausible reaction mechanism involving the formation of a [5,6]-fused palladacycle was proposed. This approach offers valuable insights for exploiting novel L,L-type TDGs.