Solid phase synthesis of biologically important indoles

Combinatorial chemistry has become an important tool in the area of modern drug discovery and its success is partly dependent on further advances of solid phase organic synthesis (SPOS). Indoles are an important class of compounds with a broad spectrum of biological activities. Therefore, considerable attention is given for the development of effective methodology for the substituted indoles not only in solution phase but also on solid phase. In this review, indole forming classical reactions such as Fisher, Nenitzescu, Bartoli, Modified Madelung, Modified Bischler, and Wittig type reactions on solid support are summarized. In addition, metal mediated cyclizations such as palladium, and rhodium catalyzed cyclizations along with microwave-assisted solid phase synthesis of indoles have been discussed. Also, the most relevant biological properties of indoles have been reported.