Silver-Catalyzed Chemo- and Regioselective Nitration of Anilides

Decarboxylation of paraconic acids using silver(I) nitrate/persulfate combination: An entry to β-nitro- and β-hydroxy γ-butyrolactones

Decarboxylative transformations of paraconic acids, a class of γ-butyrolactones containing a carboxylic acid group at the β position as their characteristic functionality, using a combination of AgNO3/K2S2O8 was investigated. The dual function of AgNO3 as an initiator for decarboxylation process and a nitrogen dioxide radical source that reacts with aliphatic carboxylic substrates of this study was reported for the first time. Starting from paraconic acids, β-nitro- and β-hydroxy γ-butyrolactones were obtained in good combined yields (41-85% yields) with moderate selectivity in one-pot operation. The reactions completed within acceptable reaction time (2 h) under mild reaction conditions that γ-butyrolactone core could be tolerated. The present study represents the direct and site-specific entry to β-nitro- and β-hydroxy γ-butyrolactones which are important precursors in organic transformations.

K2S2O8 activation by glucose at room temperature for the synthesis and functionalization of heterocycles in water

While persulfate activation at room temperature using glucose has primarily been focused on kinetic studies of the sulfate radical anion, the utilization of this protocol in organic synthesis is rarely demonstrated. We reinvestigated selected K₂S₂O₈-mediated known organic reactions that invariably require higher temperatures and an organic solvent. A diverse, mild functionalization and synthesis of heterocycles using the inexpensive oxidant K₂S₂O₈ in water at room temperature is reported, demonstrating the sustainability and broad scope of the method. Unlike traditional methods used for persulfate activation, the current method uses naturally abundant glucose as a K₂S₂O₈ activator, avoiding the use of higher temperature, UV light, transition metals or bases.

Silver-catalysed C–H bond activation: a recent review

Transition metal catalysed C–H activations are efficient, simple, mild, cost-effective and stereoselective, and many of them are environmentally sustainable transformations.

Steering Site-Selectivity in Transition Metal-Catalyzed C-H Bond Functionalization: the Challenge of Benzanilides

Selective C-H bond functionalization catalyzed by metal complexes have completely revolutionized the way in which chemical synthesis is conceived nowadays. Typically, the reactivity of a transition metal catalyst is the key to control the site-, regio- and/or stereo-selectivity of a C-H bond functionalization. Of particular interests are molecules that contain multiple C-H bonds prone to undergo C-H bond activations with very similar bond dissociation energies at different positions. This is the case of benzanilides, relevant chemical motifs that are found in many useful fine chemicals, in which two C-H sites are present in chemically different aromatic fragments. In the last years, it has been found that depending on the metal catalyst and the reaction conditions, the amide motif might behave as a directing group towards the metal-catalyzed C-H bond activation in the benzamide site or in the anilide site. The impact and the consequences of such subtle control of site-selectivity are herein reviewed with important applications in carbon-carbon and carbon-heteroatom bond forming processes. The mechanisms unraveling these unique transformations are discussed in order to provide a better understanding for future developments in the field of site-selective C-H bond functionalization with transition metal catalysts.