Compared with β-carbon elimination, oxidative addition of C-C bond is a more direct way of C-C bond activation. However, it is more challenging to do for the following reasons: 1) It forms two weak M-C bonds at the expense of breaking a stable C-C bond, so it is energetically unfavorable; 2) the C-C bond is usually hindered, which makes the metal center hard to approach. As a result, the cleavage of unstrained compounds that have been achieved is mainly focused on ketone substrates. This is because the C–C bond adjacent to the carbonyl of ketones is weaker and can be much more easily cleaved. It also benefits from the less steric hindrance from the planar structure of the carbonyl motif. Suggs and Jun are pioneers in this field. They found that an Rh(I) complex, [RhCl(CH)], can be oxidatively inserted into the C–C bond of 8-acylquinolines at the 8-position to form relatively stable 5-membered rhodacycles. Subsequently,  8-acylquinoline can be coupled with ethylene to afford 8-quinolinyl ethylketone, which represented the first transition-metal-catalyzed scission of C–C bonds via oxidative addition.