Ruthenium-Catalyzed Amide-Bond Formation

Abstract

The amide functionality is one of the most important functional groups in organic and biological chemistry. Classical synthetic strategies of amides involve the stoichiometric, and poor atom efficient, reaction of amines with carboxylic acid derivatives. Transition-metal-catalyzed reactions have emerged in recent years as more atom-economical and powerful tools for preparing amides, opening previously unavailable routes from substrates other than the carboxylic acids and their derivatives. Ruthenium-based catalysts have been at the heart of these advances, and this chapter pretends to give an overview of the field. Among others, the following ruthenium-catalyzed synthetic approaches of amides will be discussed: the hydration of nitriles, the hydrolytic amidation of nitriles with amines, the rearrangement of aldoximes, the coupling of aldehydes with hydroxylamine, and the dehydrogenative amidation of alcohols, aldehydes and esters.

Rhodium-catalyzed oxidative amidation of allylic alcohols and aldehydes: effective conversion of amines and anilines into amides

“… 2 While these reactions are versatile and widely employed, there are significant drawbacks associated with them: they generate super-stoichiometric quantities of high molecular weight byproducts and are not functional group tolerant. 3 The transition metal-catalyzed oxidative amidation of alcohols 4 and aldehydes 5 is a promising alternative to traditional coupling methods, 6 , 7 as it allows for the generation of amides along with molecular hydrogen as the only by-product ( Scheme 1 ). For example, Misltein and Madsen reported an acceptorless oxidative amidation of alcohols using Ru catalysis with pincer 4 c and NHC 4 e ligands, respectively.…”

Editorial of Special Issue Ruthenium Complex: The Expanding Chemistry of the Ruthenium Complexes

“…In an innovatory undertaking, graphene oxide was used to support ruthenium catalysts in order to activate self-healing in multifunctional materials that are able to simultaneously integrate the healing process with the advantageous properties of graphene-based materials [159]. Part of a large body of work concerns fundamental reactions studied anew with Ru complexes including hydrogenation and transfer hydrogenation; oxidation and hydroxylation; C–C, C–X and N–X bond formation; olefin metathesis and related C–C couplings; alkylation; arylation; isomerization; epimerization; condensation; cyclization; atom transfer radical reactions; oligomerization and polymerization [160,161,162,163,164,165,166,167,168,169,170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186,187,188,189,190,191,192,193]. Among non-metathetical reactions, the versatile and easy to handle transfer hydrogenation is often chosen as standard method for appraising and comparing the catalytic activity of ruthenium promoters [167,168,169,170,171,172,173].…”

Near-Ambient-Temperature Dehydrogenative Synthesis of the Amide Bond: Mechanistic Insight and Applications

“… The reaction proceeds upon refluxing the alcohol and amine in toluene in the presence of a Ru–PNN catalyst. Since then, many research groups including the groups of Madsen, Crabtree, Hong, Hazari and Bernskoetter, Prakash, and others have reported efficient catalysts that can catalyze the acceptorless dehydrogenative coupling of alcohols and amines under various conditions . Importantly, first-row transition-metal-based complexes have also been reported for this transformation by the groups of Bernskoetter (iron) and ours (manganese).…”