Anil K. Mandadapu

Gold-Catalyzed Sequential Alkyne Activation: One-Pot Synthesis of NH-Carbazoles via Cascade Hydroarylation of Alkyne/6-Endo-Dig Carbocyclization Reactions

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.

Cascade intermolecular Michael addition-intramolecular azide/internal alkyne 1,3-dipolar cycloaddition reaction in one pot.

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.

Synthesis of Iodo-Indoloazepinones in an Iodine-Mediated Three-Component Domino Reaction via a Regioselective 7-endo-dig Iodo-Cyclization Pathway±CDRI Communication No. 8094

An efficient and rapid synthetic strategy for the naturally occurring indoloazepinone scaffold via a three-component reaction of indole-2-carboxamides, 1,3-disubstituted propargyl alcohols, and I(2) is described. The strategy involves a C-H functionalization-alkyne activation-intramolecular hydroamidation-deprotonation domino sequence. The salient feature of this sequence is regioselective electrophilic 7-endo-dig iodo-cyclization during the intramolecular hydroamidation to afford a seven-membered azepinone ring annulated to the indole.

Unprecedented Cu-Catalyzed Coupling of Internal 1,3-Diynes with Azides: One-Pot Tandem Cyclizations Involving 1,3-Dipolar Cycloaddition and Carbocyclization Furnishing Naphthotriazoles†

A one-pot protocol for the synthesis of triazole-annulated polyheterocycles via metal-catalyzed coupling of internal 1,4-disubstituted 1,3-diynes and organic azides has been described. The mechanistic rationale for the reaction suggests tandem cyclizations involving copper-catalyzed cycloaddition and 6-endo carbocyclization reactions. The cascade cyclization leads to an increase in molecular complexity to furnish naphtho[1,2-d]triazoles in satisfactory yields. The generality of the method has been demonstrated by using a series of aromatic/aliphatic azides and symmetrical internal 1,3-diynes.

Pictet-Spengler Reaction Revisited: Engineering of Tetherd Biheterocycles into Annulated Polyheterocycles

This micro review focuses on the application of the modified Pictet-Spengler reaction to the synthesis of diverse polyheterocy- cles with structural resemblance to natural products. The modified Pictet-Spengler reaction takes use of tethered biheterocycles compris- ing nucleophilic partner and a source for electrophilic partner followed by their condensation with aldehydes/ketones to furnish annulated polyheterocycles. Using this strategy engineering of numerous tethered biheterocycles into annulated polyheterocycles has been success- fully carried out using both 6-endo as well as 7-endo cyclizations.