Several easy, efficient and convenient procedures to access indoles fused heterocyclic systems are described in this review. These heterocyclic systems were synthesized from several cyclic or acyclic molecules via a variety of reactions such as Diels-Alder reaction, Michael addition, Morita- Baylis-Hillmann reaction and many other domino/Cascade approaches with high selectivity. Most of the given protocols in this review proceed through organocatalytic pathways; however, some underwent different catalytic and non-catalytic reactions.
