ipso-Annulation represents an attractive approach to synthesize a variety of spirocyclic compounds having a quaternary carbon center. Furthermore, these compounds also serve as a handy synthon for the construction of various complex molecules. This review presents various useful approaches for the intramolecular ipso-cyclization to afford a wide range of spirocyclohexadienones. In addition, the utility of spirocyclic compounds towards the synthesis of complex molecules is also included.

A novel methodology for the synthesis of 5-selenyl/sulfenyl nicotinates involving copper-catalyzed organochalcogenyl aza-annulation of enynyl azide with diorganyl-dichalcogenides has been described. This method offers difunctionalization of alkynes via regioselective intramolecular chalcogenoamination in one pot to provide substituted 5-chalcogenyl nicotinates in good to excellent yields. The resulting nicotinates provide access to their oxides, sulfones, and acid derivatives.

Novel Δ2-isoxazoline fused cyclopentane derivatives have been synthesized and evaluated for their antimicrobial and anticancer activities.

An unprecedented copper-catalyzed aminative aza-annulation of enynyl azide using commercially available N-fluorobenzenesulfonimide (NFSI) as an amination reagent is described. The reaction proceeds via regioselective inter-/intramolecular diamination, incorporating one nitrogen from the NFSI and the other from the azide, to provide amino-substituted nicotinate derivatives in a single step with moderate to high yield. This method represents an efficient way to access diverse aminonicotinates through direct C-N bond-coupling processes.

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Novel triazole-linked indole and oxindole glycoconjugates as inhibitors of the Akt/PKB signaling pathway.

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A strategy to functionalized spiro[4.5]­trienones, by domino silver-catalyzed decarboxylative acylation or alkylation/ ipso-cyclization of N-arylpropiolamides with α-keto acids/alkyl carboxylic acids, is presented. This transformation offers a wide range of substituted 3-acyl/alkyl-spiro[4.5]­trienones in high yields with a broad substrate scope. The approach was further extended to access fused tricyclic frameworks, 6,7-dihydro-3H-pyrrolo­[2,1-j]­quinoline-3,9­(5H)-diones.