Te(II)-Catalyzed Cross-Dehydrogenative Phenothiazination of Anilines.

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.

Cross-dehydrogenative N-N couplings.

The relatively high electronegativity of nitrogen makes N-N bond forming cross-coupling reactions particularly difficult, especially in an intermolecular fashion. The challenge increases even further when considering the case of dehydrogenative N-N coupling reactions, which are advantageous in terms of step and atom economy, but introduce the problem of the oxidant in order to become thermodynamically feasible. Indeed, the oxidizing system must be designed to activate the target N-H bonds, while at the same time avoid undesired N-N homocoupling as well as C-N and C-C coupled side products.

Cross-Dehydrogenative N-N Coupling of Aromatic and Aliphatic Methoxyamides with Benzotriazoles.

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.

-Selective Dehydrogenative Phenothiazination of Hydroquinolines and Indolines.

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, -selective C-N bond formation between phenothiazines and quinolines or indolines under extremely mild and user-friendly conditions.

Proline bulky substituents consecutively act as steric hindrances and directing groups in a Michael/Conia-ene cascade reaction under synergistic catalysis.

In this study, we report a highly stereoselective and versatile synthesis of spiro pyrazolones, promising motifs that are being employed as pharmacophores. The new synthetic strategy merges organocatalysis and metal catalysis to create a synergistic catalysis using proline derivatives and Pd catalysts. This protocol is suitable for late-stage functionalization, which is very important in drug discovery.