Bis-N-heterocyclic Carbene Aminopincer Ligands Enable High Activity in Ru-Catalyzed Ester Hydrogenation

Filonenko, Georgy A.; Aguila, Mae Joanne B.; Schulpen, Erik N.; Putten, Robbert van; Wiecko, Jelena; Müller, Christian; Lefort, Laurent; Hensen, Emiel J. M.; Pidko, Evgeny A.

doi:10.1021/jacs.5b04237

Cited by 94 publications

(47 citation statements)

References 32 publications

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“…Fig. 21 [109][110][111]. It is striking that also for the displayed catalysts, a wide range of aromatic and aliphatic esters is transformed to its respective alcohols.…”

Section: Table 16mentioning

confidence: 99%

Current advances on ruthenium(II) N-heterocyclic carbenes in hydrogenation reactions

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et al. 2018

Coordination Chemistry Reviews

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This review provides a brief overview of advances on ruthenium(II) N-heterocyclic carbene complexes 30 (NHCs) applied for hydrogenation reactions undertaken during the last five years. Several structural 31 motifs, containing mono-, bi-, tri-and tetradentate binding modes of the NHCs are discussed in combi-32 nation with a variety of different wingtip substituents to provide active catalysts for hydrogenation reac-33 tions. While bidentate ligands are the more active catalysts than their monodentate analogues, pincer 34 ligands must be chosen carefully to enable the formation of a free coordination site in catalysis. 35 Transfer hydrogenation and direct hydrogenation of ketones and aldehydes, olefins, nitriles, imines 36 and esters are summarized, showing the trend towards hydrogen transfer from other sources than hydro-37 gen gas. Recently developed chiral NHCs offer the opportunity for asymmetric transformations as a pos-38 sible pathway to access natural products.

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“…Fig. 21 [109][110][111]. It is striking that also for the displayed catalysts, a wide range of aromatic and aliphatic esters is transformed to its respective alcohols.…”

Section: Table 16mentioning

confidence: 99%

Current advances on ruthenium(II) N-heterocyclic carbenes in hydrogenation reactions

Hey

Reich

Baratta

et al. 2018

Coordination Chemistry Reviews

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“…41 A significant recent advance in this area is the development of active Ni(II) CNC pre-catalysts. 42 Well defined platinum-metal-based CNC and CCC pincers have been used to promote a variety of other transformations, including hydrogenation (Ru, Rh), 14,20,30,33,44,45 hydrosilylation (Rh, Pd), 33,35 hydroamination (Rh, Ir, Pd, Pt), 28,46 hydrovinylation (Pt), 47 acceptorless alkane dehydrogenation (Ir, e.g. 2), 48,49 and aryl C-H bond borylation (Ir).…”

Section: Applicationsmentioning

confidence: 99%

NHC-based pincer ligands: carbenes with a bite

2016

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“…[11] In addition, very recently ah ighly active bis-NHC amino pincerR uc omplexh as been developed for ester hydrogenation. [12] Despite the recent progress with these Ru-based materials,t he development of inexpensive,e arthabundant metal catalysts is desirable.I nt his context, iron-based catalysts are of special interest due to their low cost, low toxicity and high abundance. [13] In the past year, significant advancesh ave been achieved in our group [14] ando thers [15] using well-defined ironbased pincerc omplexes (Figure 1), which were successfullya pplied in selective hydrogenation and dehydrogenation reactions.…”

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Improved Second Generation Iron Pincer Complexes for Effective Ester Hydrogenation

et al. 2016

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Hydrogenation of esterst oa lcoholsw ith aw ell-definedi ron iPr2 PNP pincerc omplexh as been recently reported by us and other groups.W en ow introduce an ovel and sterically less hindered Et2 PNP congener that provides superior catalytic activity in the hydrogenation of various carboxylic acid esters and lactones comparedt ot he known complex. Successful hydrogenation proceeds under relatively mild conditions (60 8 8C) with lower catalyst loadings.Keywords: alcohols;c atalytic hydrogenation;esters; iron;p incer complexes Thec atalytic hydrogenation of esterst ot he corresponding alcohols represents an interesting methodology of paramount importance for organic synthesis and fine chemical processes.[1] In the past, this transformation relied on the use of stoichiometrica mounts of inorganic metal hydridess uch as LiAlH 4 ,N aBH 4 and related compounds resulting in the formation of stoichiometrica mounts of waste products followed by complexw ork-upp rocedures .[2] In contrast, catalytic hydrogenation of esters and lactonese mploying H 2 constitutes ac ompletely atom economic, waste-free and environmentally benign transformation. Heterogeneousc atalysts are applied in the hydrogenation of fatty estersb ut these catalysts require high temperature andp ressure.[3] Hence,t he development of milder and more selective catalytic protocols for ester hydrogenation facilitated by well-defined homogeneous complexes constitutes an actual and highly desired research goal. [4] In the early 2000s av ariety of seminal reportso n homogeneous catalysts for the hydrogenation of estersa ppeared in the literature. [5][6][7] Major developments in this field were madeb yt he groups of Milstein, [8] Saudan, [9] Kuriyama, [10] andG usev. [11] In addition, very recently ah ighly active bis-NHC amino pincerR uc omplexh as been developed for ester hydrogenation. [12] Despite the recent progress with these Ru-based materials,t he development of inexpensive,e arthabundant metal catalysts is desirable.I nt his context, iron-based catalysts are of special interest due to their low cost, low toxicity and high abundance. [13] In the past year, significant advancesh ave been achieved in our group [14] ando thers [15] using well-defined ironbased pincerc omplexes (Figure 1), which were successfullya pplied in selective hydrogenation and dehydrogenation reactions.[16] Based on our experience in this redox catalysis, [17] we became interested in the development of similar applications using an iron-based catalyst.Inspired by our recent worko nt he hydrogenation of esters to alcohols [14b] conducted with the isopropyltaggedi ron-PNP pincerc omplex 1,w ef ocused on the preparation of two novelc ongeners 2 and 3 bearing phosphinem otifsw ith different stericd emands (Figure 2). Herein, we address the influence of the alkyl substituents at the phosphorus binding site on

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Bis-N-heterocyclic Carbene Aminopincer Ligands Enable High Activity in Ru-Catalyzed Ester Hydrogenation

Cited by 94 publications

References 32 publications

Current advances on ruthenium(II) N-heterocyclic carbenes in hydrogenation reactions

Current advances on ruthenium(II) N-heterocyclic carbenes in hydrogenation reactions

NHC-based pincer ligands: carbenes with a bite

Improved Second Generation Iron Pincer Complexes for Effective Ester Hydrogenation

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