Catalytic Hydrogenation of Carboxylic Acid Esters, Amides, and Nitriles with Homogeneous Catalysts

Abstract

This review describes the catalytic reduction of amides, carboxylic acid esters and nitriles with homogeneous catalysts using molecular hydrogen as an environmental friendly reducing agent.

Catalytic Hydrogen Production by Ruthenium Complexes from the Conversion of Primary Amines to Nitriles: Potential Application as a Liquid Organic Hydrogen Carrier

“…[21,22] The futureo fl iquid organich ydrogen carriers (LOHC) depends on ar eversiblec hemical reactionb ased on the release and uptake of hydrogen. [30][31][32][33][34][35] Nitriles are versatile intermediates in organic synthesis owing to their direct conversion into av arietyo ff unctionalg roups.C onventional organic procedures requiren ucleophilic displacemento fs uitable leaving groups producing stoichiometrica mounts of waste and with limited selectivity. [28] The acceptorless dehydrogenation of primary amines generates the corresponding nitrile and two moles of hydrogen.…”

Ruthenium‐Catalyzed Deaminative Hydrogenation of Aliphatic and Aromatic Nitriles to Primary Alcohols

“…General procedure for Tables 2a nd 3 An approximately 80 mL Fischer-Porter-type glass autoclave was charged with RuHCl(CO)(PPh 3 ) 3 (0.03 mmol, 28.6 mg), the nitrile (3.0 mmol), degassed 1,4-dioxane (3.0 mL), and degassed water (3.0 mL) in air.A fter closing the reaction vessel, the system was purged first with nitrogen (3-5 )a nd then with hydrogen (3)(4)(5). Finally,t he autoclave was pressurized with hydrogen (10 bar) and placed into ap reheated oil bath (120 or 140 8C).…”

Hydrogen

“…This chemistry has been recently reviewed. 73 Hydrogenation of esters is a more developed technique 73-75 with selected examples including reduction of aryl and alkyl carboxylic esters, and selective reduction of esters without concomitant reduction of pendant alkene functionality, and reduction of lactones to give diols (eqs 29 and 30). 75 The hydrogenation of trifluoroacetic esters to alcohols has been achieved under mild and selective conditions using iron-pincer complexes as catalysts.…”

“…Subsequent reduction provides either the amine or the alcohol (eq 31). 73 Reductive cleavage of amides can be catalyzed with dearomatized Ru-pincer complexes and provides an amine and an alcohol. 73, 77 The more interesting reduction of the carbonyl of the amide to a methylene, has also been achieved although aggressive conditions are required and mixtures of primary, secondary, and tertiary amines may be formed.…”