Cyanidation Of C - H Bond Catalyzed By Transition Metal

Aryl nitriles as key structural units exist in numerous dyes, pesticides,pharmaceuticals and natural products. Therefore, the preparation of nitriles has always been an attractive topic in organic synthesis. In the past decades,transition-metal-catalyzed direct C-H cyanation was still an appealing strategy to synthesize aromatic nitriles. It avoids the disadvantages of general methods such as harsh reaction conditions and the use of stoichiometric amounts of toxic metal cyanides.This paper developed a bidentate-chelation assistant palladium-catalyzed direct C-H cyanation of picolinamides with TMSCN.Amide was choosen as the directing group to synthesize monodentate N-(naphthalen-1-yl)benzamide, 2-chloro-N-(naphthalen-1-yl)nicotinamide, N-(quino-lin-8-yl)benzamide and N, O-bidentate chelated N-(naphthalen-1-yl)furan-2-carboxamide, N, N-bidentate chelated N-(naphthalen-1-yl)picolinamide. After comparison of their reactivity, we chose N-(naphthalen-1-yl)picolinamide as substrates and 17 derivatives have been synthesized.The reaction of N-(naphthalen-1-yl) picolinamide in the presence of Pd(PPh3)4 as catalyst and TMSCN as cyanide source was investigated. In order to improve the yield,the reaction was conducted by changing the reaction parameters, including catalyst,oxidant, cyanating reagent, solvent, temperature and atmosphere. Having established the optimized reaction conditions, the generality of the reaction was investigated by using various substrates. At last, 14 aromatic nitriles have been achieved. Moreover, a mechanism of this cyanation reaction was proposed.