Perspectives on metal-catalysed syntheses of carbolines (α/β/γ/δ): recent advances

from indole substrates. In addition, simultaneous formation of both pyrrole and pyridine rings is also adopted in the construction of carbolines. Among these methods, metal-catalysed synthesis has made remarkable advances in the recent past due to the unique reactivity and the flexibility in using different substrates. This review intends to provide a brief yet comprehensive account of these methods for the synthesis of carboline isomers, which have mostly appeared in the literature in the last two and a half decades, along with the mechanistic pathways involved therein.