ABSTRACT
Heterocycles have contributed to the understanding of life processes as well as to the development of society from an industrial and biological point of view. This chapter describes the approaches for the preparation of fused five-membered nitrogen heterocycles through metal- and non-metal-assisted reactions. Q. Cai et al. reported a tandem synthesis of fused heterocyclic scaffolds 4-oxo-indeno[1,2-b] pyrroles using cuprous iodide catalyst by reacting alkynyl decorated acetophenones and isocyanides. W. F. Bailey et al. reported a method involving intramolecular carbolithiation of aryllithium (formed from (N,N-diallylamino)bromopyridine) for the synthesis of 3-substituted 4-, 5-, 6-, and 7-azaindolines (2,3-dihydro-1H-pyrrolopyridines). J. Boivin et al. and S. Z. Zard reported N-radical formation through the reactions of oxime derivatives with nickel powder and stannane and their addition to intramolecular alkenes. However, both these reactions had some disadvantages in the operation procedure and the generality.
