Hydrogenation of Esters to Alcohols Catalyzed by Defined Manganese Pincer Complexes

Elangovan, Saravanakumar; Garbe, Marcel; Jiao, Haijun; Spannenberg, Anke; Junge, Kathrin; Beller, Matthias

doi:10.1002/anie.201607233

Cited by 277 publications

(131 citation statements)

References 61 publications

(24 reference statements)

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“…Amore sustainable approach would be the use of catalysts based on abundantly available 3d metals,s uch as Co,F e, and Mn (nonprecious or base metals), to additionally conserve our rare noble metal resources.M ilstein and co-workers recently introduced ac obalt-catalyzed synthesis of pyrroles from diols and amines [10] (Scheme 1, top). [11] We recently introduced av ariety of nonprecious metal catalysts for reactions involving (de)hydrogenation steps [11d, 12-15] and report here on am anganese-catalyzed version of the multicomponent reaction of alcohols and amidines to form pyrimidines [7] (Scheme 1, bottom). [5a] Thenonprecious metal manganese,the third most abundant metal in the earthscrust, has been overlooked in recent years with regard to catalysis involving a( de)hydrogenation step.…”

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confidence: 99%

Manganese‐Catalyzed Multicomponent Synthesis of Pyrimidines from Alcohols and Amidines

2017

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The development of catalytic reactions for synthesizing different compounds from alcohols to save fossil carbon feedstock and reduce CO emissions is of high importance. Replacing rare noble metals with abundantly available 3d metals is equally important. We report a manganese-complex-catalyzed multicomponent synthesis of pyrimidines from amidines and up to three alcohols. Our reaction proceeds through condensation and dehydrogenation steps, permitting selective C-C and C-N bond formations. β-Alkylation reactions are used to multiply alkylate secondary alcohols with two different primary alcohols to synthesize fully substituted pyrimidines in a one-pot process. Our PN P-Mn-pincer complexes efficiently catalyze this multicomponent process. A comparison of our manganese catalysts with related cobalt catalysts indicates that manganese shows a reactivity similar to that of iridium but not cobalt. This analogy could be used to develop further (de)hydrogenation reactions with manganese complexes.

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confidence: 99%

Manganese‐Catalyzed Multicomponent Synthesis of Pyrimidines from Alcohols and Amidines

2017

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“…[15] Fort he last decade,t he implementation of cheap,e arth abundant, non-noble metals for (de)hydrogenation reactions has attracted significant interest in homogeneous and heterogeneous catalysis. [16] As acomplement to molecularly defined organometallic complexes,heterogeneous materials based on iron and cobalt are also applied in advanced organic synthesis. [17] Fore xample,w ed eveloped novel nanostructured heterogeneous catalysts modified by N-doped graphene for several redox reactions;i ncluding hydrogenation of nitroarenes,k etones,n itriles,a nd oxidations of alcohols.…”

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A Biomass‐Derived Non‐Noble Cobalt Catalyst for Selective Hydrodehalogenation of Alkyl and (Hetero)Aryl Halides

et al. 2017

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Hydrodehalogenation is astraightforwardapproach for detoxifications of harmful anthropogenic organohalidebased pollutants,aswell as removal of halide protecting groups used in multistep syntheses.An ovel sustainable catalytic material was prepared from biowaste (chitosan) in combination with an earth-abundant cobalt salt. The heterogeneous catalyst was fully characterized by transmission electron microscope,X -rayd iffraction, and X-ray photoelectron spectroscopym easurements,a nd successfully applied to hydrodehalogenation of alkyla nd (hetero)aryl halides with broad scope (> 40 examples) and excellent chemoselectivity using molecular hydrogen as ar eductant. The general usefulness of this method is demonstrated by successful detoxification of non-degradable pesticides and fire retardants.M oreover,t he potential of the catalyst as adeprotection tool is demonstrated in am ultistep synthesis of (AE)-peronatin B( alkaloid).Hydrodehalogenation constitutes an important organic transformation where ahalogen atom is formally substituted with ahydrogen atom. It has become an enabling technology for degradation of anthropogenic and environmentally deleterious chemicals into their less noxious congeners.T he former are often produced in industrial processes and can include polyhalogenated organic pollutants (such as,p olychlorodioxins and polychlorophenols), toxic and persistent pesticides,and fire retardants.[1, 2] Furthermore,hydrodehalogenation reactions are often used in organic synthesis for deprotection chemistry,s ince halides can selectively block one of two reaction sites with similar reactivity without strongly influencing the electronics of the system. [2,3] Additionally,s tereoselective hydrodehalogenation of prochiral gem-dihalo-organic compounds affords chiral halo-organic compounds. [4] Hydrodehalogenation reactions have been performed with various methods,s uch as metal-halogen exchange, [2, 5] metal-mediated reduction, [2,6] photochemical reduction, [7] and reductive radical dehalogenation.[8] Some of these reactions are marred by the use of toxic and explosive reagents, production of stoichiometric metal waste,poor selectivity,and low functional-group tolerance.Nevertheless,there has been an intense research interest in developing more efficient and reliable transition-metal-catalyzed hydrodehalogenation processes (mostly involving,Pd, [9] Rh, [10] Ru, [11] Ni, [4,12] and Fe [13] ) using Grignard reagents, [12c,13] alcohol and base, [9a, 10c, 11a,c] hydrides, [4,9b,c, 12b,d,14] formic acid [9h] or its salt, [9e] hydrazine, [9d] and molecular hydrogen. [9c,f,g,10a,b, 11b,12a] Obviously,f rom an ecological perspective,t he later reagent is considered to be the most efficient, clean, and atom-economical reductant. [15] Fort he last decade,t he implementation of cheap,e arth abundant, non-noble metals for (de)hydrogenation reactions has attracted significant interest in homogeneous and heterogeneous catalysis.[16] As acomplement to molecularly defined organometallic complexes,heter...

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“…So far, all these cobalt catalysts have been tested for a relatively small number of esters with a limited tolerance of functional groups leaving space for improvements. Here, based on our experiences in non‐noble‐metal‐catalyzed reductions, we report the development of a more general applicable cobalt catalyst for the hydrogenation of various carboxylic acid esters.…”

Section: Figurementioning

confidence: 99%

Cobalt Pincer Complexes for Catalytic Reduction of Carboxylic Acid Esters

Junge

Wendt

Cingolani

et al. 2017

Chemistry A European J

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Hydrogenation of Esters to Alcohols Catalyzed by Defined Manganese Pincer Complexes

Cited by 277 publications

References 61 publications

Manganese‐Catalyzed Multicomponent Synthesis of Pyrimidines from Alcohols and Amidines

Manganese‐Catalyzed Multicomponent Synthesis of Pyrimidines from Alcohols and Amidines

A Biomass‐Derived Non‐Noble Cobalt Catalyst for Selective Hydrodehalogenation of Alkyl and (Hetero)Aryl Halides

Cobalt Pincer Complexes for Catalytic Reduction of Carboxylic Acid Esters

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