Highly Selective Iron‐Catalyzed Synthesis of Alkenes by the Reduction of Alkynes

Enthaler, Stephan; Haberberger, Michael; Irran, Elisabeth

doi:10.1002/asia.201000941

Cited by 80 publications

(34 citation statements)

References 97 publications

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“…This procedure was also applied to the hydrogenation reactions of 1,2‐diarylethynes, which were clean converted into their corresponding alkanes at 4 bar H 2 pressure (Table 5). 10b At lower temperatures and lower H 2 pressures, moderate chemo‐ and stereoselectivity for the formation of the ( Z )‐stilbene was observed ( Z / E =3:1, 78 % overall yield) 10e…”

Section: Hydrogenation Reactionsmentioning

confidence: 99%

Iron(0) Particles: Catalytic Hydrogenations and Spectroscopic Studies

et al. 2012

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Ironing it out: The simple pre‐catalyst system FeCl3/EtMgCl was applied to the hydrogenation of various alkenes and alkynes at room temperature. Domino iron‐catalyzed allylation/hydrogenation reactions were performed under 1–4 bar H2. Spectroscopic studies determined the heterogeneous nature of the active catalyst species, its oxidation state (Fe0), and the local structure and size of the formed particles.

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Section: Hydrogenation Reactionsmentioning

confidence: 99%

Iron(0) Particles: Catalytic Hydrogenations and Spectroscopic Studies

et al. 2012

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“…[17] Reduction of alkynes selectively to Zalkenes can be carried out using the well-known Lindlar catalyst, [18] and even base metal catalysts. [19][20] Various transition metal catalysts [5,10,13,15,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] have been developed so far which in combination with different transfer hydrogenation sources [21][22][23][24][25][26][27][28][29][30][31] or dihydrogen gas [32][33][34][35] can be used for the stereoselective semi-hydrogenation (reduction) of alkynes to olefins. In this regard, selective formation of E-alkenes is more challenging and less well-studied.…”

Section: Introductionmentioning

confidence: 99%

Ruthenium‐Catalyzed E‐Selective Partial Hydrogenation of Alkynes under Transfer‐Hydrogenation Conditions using Paraformaldehyde as Hydrogen Source

et al. 2021

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E‐alkenes were synthesized with up to 100 % E/Z selectivity via ruthenium‐catalyzed partial hydrogenation of different aliphatic and aromatic alkynes under transfer‐hydrogenation conditions. Paraformaldehyde as a safe, cheap and easily available solid hydrogen carrier was used for the first time as hydrogen source in the presence of water for transfer‐hydrogenation of alkynes. Optimization reactions showed the best results for the commercially available binuclear [Ru(p‐cymene)Cl2]2 complex as pre‐catalyst in combination with 2,2‐bis(diphenylphosphino)‐1,1‐binaphthyl (BINAP) as ligand (1 : 1 ratio per Ru monomer to ligand). Mechanistic investigations showed that the origin of E‐selectivity in this reaction is the fast Z to E isomerization of the formed alkenes. Mild reaction conditions plus the use of cheap, easily available and safe materials as well as simple setup and inexpensive catalyst turn this protocol into a feasible and promising stereo complementary procedure to the well‐known Z‐selective Lindlar reduction in late‐stage syntheses. This procedure can also be used for the production of deuterated alkenes simply using d2‐paraformaldehyde and D2O mixtures.

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“…Secondary silanes (Ph 2 SiH 2 2b and Et 2 SiH 2 2c) gave the linear silane products 4b and 4c in quantitative yield with complete regioselectivity; however tertiary silane 2d gave only small quantities of quaternary silane 4d (entries 10-12). The hydrosilylation of 1-hexene 6 with tertiary silanes, benzyldimethylsilane 2e and the industrially representative silicone polymer cross-linkers, heptamethyltrisiloxane 2f and pentamethyldisiloxane 2g, gave quaternary silanes 7e, 7f and 7g in excellent yield and with perfect regioselectivity (entries [13][14][15].…”

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confidence: 98%

“…Only limited substrate scope was disclosed and reaction times of up to 24 h and catalyst loadings of 5 mol% were required. Other notable recent examples of iron-catalysed hydrosilylation of olefins have been reported by Enthaler, [14] Plietker, [15] and Nakazawa, [16] however high temperatures and/or long reaction times were required in each case.…”

mentioning

confidence: 99%

Iron‐Catalysed Chemo‐, Regio‐, and Stereoselective Hydrosilylation of Alkenes and Alkynes using a Bench‐Stable Iron(II) Pre‐Catalyst

2014

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The chemo-, regio-, and stereoselective iron-catalysed hydrosilylation of alkenes and alkynes with excellent functional group tolerance is reported (34 examples, 41-96% yield). The catalyst and reagents are commercially available and easy to handle, with the active iron catalyst being generated in situ, thus providing a simple and practical methodology for iron-catalysed hydrosilylation. The silane products can be oxidised to the anti-Markovnikov product of olefin hydration, and the one-pot iron-catalysed hydrosilylation-oxidation of olefins to give silane(di)ols directly is also reported. The iron pre-catalyst was used at loadings as low as 0.07 mol%, and displayed catalyst turnover frequencies (TOF) approaching 60,000 mol h À1. Initial mechanistic studies indicate an iron(I) active catalyst.Keywords: catalysis; hydrosilylation; iron; olefins; synthetic methods Iron offers significant advantages as a catalyst over precious metals due to its low toxicity, low cost, natural abundance and sustainable long-term commercial availability.[1] Although iron catalysis is well established for cross-coupling [2] and redox reactions, [3] the hydrofunctionalisation of olefins has been less developed. In part, this can be attributed to the procedurally challenging reaction conditions and catalyst syntheses required, in comparison to the simplicity of ironcatalysed cross-coupling reactions. Building upon our work, [4] and previous work of others, [5] in which lowvalent iron catalysts were generated in situ, we sought to develop an operationally simple iron-catalysed hydrosilylation of olefins, in which all reagents were inexpensive, widely available and bench-stable. Furthermore, we sought to use this method for the introduction of silyl groups which could undergo further synthetic transformations (Figure 1).The hydrosilylation of alkenes and alkynes can produce alkyl-, allyl-, and vinylsilanes, [6] which are used in fine chemical synthesis for stereospecific oxidation [7] and cross-coupling reactions, [8] amongst other applications (Figure 1).[9] The cross-linking of silicone polymers by hydrosilylation represents one of the largest applications of homogeneous catalysis on an industrial scale.[6] To date, hydrosilylation has been dominated by precious metal catalysts such as platinum, palladium, ruthenium and rhodium, however these catalysts can suffer from competitive alkene isomerisation, dehydrosilylation reactions, and incompatibility with amino-substituted olefins.

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Highly Selective Iron‐Catalyzed Synthesis of Alkenes by the Reduction of Alkynes

Cited by 80 publications

References 97 publications

Iron(0) Particles: Catalytic Hydrogenations and Spectroscopic Studies

Iron(0) Particles: Catalytic Hydrogenations and Spectroscopic Studies

Ruthenium‐Catalyzed E‐Selective Partial Hydrogenation of Alkynes under Transfer‐Hydrogenation Conditions using Paraformaldehyde as Hydrogen Source

Iron‐Catalysed Chemo‐, Regio‐, and Stereoselective Hydrosilylation of Alkenes and Alkynes using a Bench‐Stable Iron(II) Pre‐Catalyst

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