In this study, we report a highly stereoselective and versatile synthesis of spiro pyrazolones, promising motifs that are being employed as pharmacophores.

Nitrogen–nitrogen bond containing motifs are ubiquitous in bioactive compounds and organic materials. However, intermolecular hetero-selective N–H/N–H oxidative coupling reactions remain very challenging and largely unexplored. Here, we report an unprecedented, simple and hetero-selective cross-dehydrogenative N–N coupling of amides and benzotriazoles, utilizing only a hypervalent iodine species as the terminal oxidant. The scope and mechanistic investigations are discussed.

Oxidative clicklike reactions are useful for the late-stage functionalization of pharmaceuticals and organic materials. Hence, novel methodologies that enable such transformations are in high demand. Herein we describe a tellurium(II)-catalyzed cross-dehydrogenative phenothiazination (CDP) of aromatic amines. A key feature of this method is a cooperative effect between the phenotellurazine catalyst and the silver salt, which serves as a chemical oxidant for the reaction. This novel catalysis concept therefore enables a considerably broader scope compared with previous chemical oxidation methods.

For more than a century, the dehydrogenative formation of N–N bonds has remained mostly confidential. Several cross-dehydrogenative N–N coupling methods have appeared recently, promising a soon to come broad applicability of the concept.

Nitrogen-containing heterocyclic systems, such as hydroquinolines, indolines, and phenothiazines, are prevalent in pharmaceuticals, natural products, and organic materials. It is therefore important to develop novel reaction strategies that give access to such biologically relevant scaffolds. This report demonstrates a novel robust, para-selective C–N bond formation between phenothiazines and quinolines or indolines under extremely mild and user-friendly conditions. Furthermore, we bring forward a surprising discovery arising from the homocoupling of indolines through an unprecedented C5-H functionalization.