An efficient and versatile method for the synthesis of indolebased polycyclic indolo-benzazepine and its derivatives through water-accelerated cationic π-cyclisation is described. The strategy involves condensation of arylamine moieties linked to C-4 in indole/azaindole systems with arylaldehydes in water containing catalytic amount of Brønsted acids. The

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A rapid one-pot protocol for the synthesis of indole-based polyheterocycles via a sequential Lewis acid catalyzed intermolecular Michael addition and an intramolecular azide/internal alkyne 1,3-dipolar cycloaddition reaction has been described. The generality of the method has been demonstrated by treating a series of aromatic/aliphatic 2-alkynyl indoles with substituted (E)-1-azido-2-(2-nitrovinyl)benzenes to furnish annulated tetracyclic indolo[2,3-c][1,2,3]triazolo[1,5-a][1]benzazepines in good yields.

A simple and efficient one-pot protocol for the synthesis of NH-carbazoles has been described. The strategy comprises a one-pot reaction involving the treatment of 2-alkynyl indoles with arylacetylenes in the presence of an Au-Ag combination catalyst. The salient feature of the strategy involves sequential activation of terminal and internal alkynes leading to the cascade hydroarylation of terminal alkynes and 6-endo-dig carbocyclization reactions. The generality of the method has been demonstrated by using a series of 2-alkynyl indoles and arylacetylenes.

A mild, efficient and versatile method has been developed for the two step synthesis of phenanthridine ring systems using the Suzuki and the modified Pictet-Spengler strategy. The strategy involves synthesis of a substrate in which an aryl amine is tethered to an activated arene ring at the carbon ortho to the activated carbon nucleophile so as to facilitate the formation of phenanthridine ring via pi-cyclization.