Ruthenium‐Catalyzed Dehydrogenation Through an Intermolecular Hydrogen Atom Transfer Mechanism

Abstract

The direct dehydrogenation of alkanes is among the most efficient ways to access valuable alkene products. Although several catalysts have been designed to promote this transformation, they have unfortunately found limited applications in fine chemical synthesis.H ere,w er eport ac onceptually novel strategy for the catalytic,intermolecular dehydrogenation of alkanes using aruthenium catalyst. The combination of ar edox-active ligand and as terically hindered aryl radical intermediate has unleashed this novel strategy.I mportantly,m echanistic investigations have been performed to provideaconceptual framework for the further development of this new catalytic dehydrogenation system.

Direct Synthesis of Enamides via Electrophilic Activation of Amides

“…Whereas routes for the direct desaturation to form enecarbamates have recently become well established, pathways leading from carboxamides to enamides remain elusive (Scheme A). Gevorgyan reported a photoinduced palladium-catalyzed dehydrogenation protocol enabled by hydrogen abstraction and starting from prefunctionalized 2-iodobenzamides, while Morandi et al recently published a ruthenium-catalyzed variant of this reaction . Additionally, an electrochemical approach for such an oxidation has been developed.…”

Cobalt-catalyzed chemoselective dehydrogenation through radical translocation under visible light

“…In general, highly reactive radical species are the key intermediates for intra- or intermolecular selective HAT efficiently. 3,4 In 2012, Baran et al developed a TEMPO-mediated remote dehydrogenation with aryltriazenes as aryl radical precursors. 3 b Recently, Gevorgyan et al have developed elegant strategies which employed reactive C-radical species produced from aryl or alkyl iodides to mediate the remote dehydrogenation by palladium photocatalysis.…”

Selective desaturation of amides: a direct approach to enamides

“…2 Thus, the synthesis of enamides has attracted great interest from chemists for several decades. 3 Recently, selective C(sp 3 )–H bond desaturation has been widely used in organic synthesis, including oxidative desaturation, 4 transition-metal catalyzed desaturation, 5 photochemical desaturation 6 and electrochemical desaturation. 7 However, compared to the dehydrogenation reaction of carbonyl compounds, 7 a , b , e , g ,8 such as ketones, 9 the regioselective dehydrogenation of N -alkanoylamides on the N -alkyl side with higher C–H bond dissociation energy (BDE) 10 is still a tremendous challenge (Scheme 1a).…”