Cobalt and Nickel Catalyzed Reactions Involving CH and CN Activation Reactions

Abstract

IntroductionHomogeneous transition metal catalyzed reactions have been very well studied over the past 50 years. The metal complexes used to accomplish these reactions have typically included noble transition metals or fi rst row metals. Due to the cost and pathogenicity of these noble metals, the development of new catalytic routes using non -precious metals is an active area of research. In this chapter, a review of the use of selected cobalt and nickel species towards catalytic reactions analogous to those seen with noble metals is presented. Catalysis with CobaltTransition metal catalyzed hetero -annulation provides a useful and convenient tool for the construction of N -heterocycles [1] . Quinolines are of special interest in that they display attractive applications in pharmaceuticals and are synthetic building blocks [2,3] . Catalytic processes employing palladium [4 -6] , rhodium [7 -9] , ruthenium [10 -14] , and iron [15] have been studied and developed to synthesize quinoline skeletons. There are fi ve common methods used to prepare substituted quinolines: the Skraup reaction [16] , the Doebner -Von Miller reaction [17] , the Conrad -Limpach reaction [18] , the Friedlaender reaction [19,20] , and the Pfi tzinger reaction [21,22] . All fi ve of the reactions require environmentally unfriendly acids or bases, high temperatures, or harsh conditions. Quinoline yields are usually low due to numerous side reactions. Even though much work has been done to fi nd catalytic routes to quinolines, the use of non -precious metals remains an active area of research.Recently, Jones et al. have published work on the conversion of diallylanilines and arylimines to quinolines [23,24] . It was found that N -allylaniline, when heated in the presence of 10 mol% Co 2 (CO) 8 and 1 atm of CO at 85 ° C, leads to the selective formation of 2 -ethyl -3 -methylquinoline (Equation (6.1) ). Aniline and propene 6 Catalysis Without Precious Metals. Edited by R. Morris Bullock