ortho-Olefination of Arylaldehyde O-Methyloximes through Palladium-Catalyzed C-H Activation

Palladium(II)-catalyzed ortho-olefination of arylaldehyde O-methyloximes by using O-methyloxime as a directing group gave 2-alkenylarylaldehyde O-methyloximes in moderate to good yields. After various reaction parameters (catalyst, oxidant, solvent, and reaction temperature) were examined, the optimal conditions for the reaction were identified. 2-Alkenylarylaldehydes could be obtained conveniently by hydrolysis of the coupling products. The kinetic isotope effect (kH/kD) for the CH bond activation was provided, and the possible mechanism of the reaction was proposed.