Studies On Transition Metal-catalyzed Cyanation Of (Hetero) Aromatic Compounds Via The Cleavage Of C-C Bonds

In recent years, nitriles and their derivatives have played an important role inorganic synthesis due to the special functional group of "-CN", which have beenalways used as the intermediates in the synthesis of natural products, medicines,agricultural chemicals and organic dyes etc. Furthermore, they could also be easilyconverted to some other derivatives such as amines, acylamides, aldehydes, ketonesand carboxylic acids under the mild reaction conditions. Thus, an efficient way for thesynthesis of these compounds is of particularly importance and highly desired.In the present study, we investigated the transition metal catalyzed the cyanationof N-protected indoles and their derivatives through the C-C cleavage of acetonitrile.Moreover, the aromatic nitriles could be also efficiently generated by employingphenylacetic acids and their derivatives as the starting materials and ammonia as the“N” source through the copper catalyzed decarboxylation of phenylacetic acids underthe oxygen atmosphere. The corresponding experimental products confirmed by GC,GC-MS, and NMR analysis, respectively.(1) We first investigated the reactivities of this rection by employing N-protectedindoles and their derivatives as the substrates and acetonitrile as the nitrile sourceunder the different reaction conditions. Under the optimal reaction conditions, we alsosynthesized lots of N-protected indole derivatives, and found that they have a moderatereactivity in this reaction, and can approach the cyanation selectively.(2) We further studied the reaction of copper catalyzed cyanation of phenylaceticacids, by using ammonia as the nitrile source and oxygen as the oxidant. It is noted thatThe cyanation reaction of phenylacetic acids could proceed smoothly in the presenceof copper acetate (20mol%) and oxygen (50mL,1atm), via using TEMPO (5mol%)as the pro-oxidant and2,2-bipyridine (5mol%) as the ligand at100oC. The reactionshows highly selectivity and different N-substituted substrates could be survive in thereaction.