Using alcohols as simple H<sub>2</sub>-equivalents for copper-catalysed transfer semihydrogenations of alkynes

Kaicharla, Trinadh; Zimmermann, Birte; Oestreich, Martin; Teichert, Johannes F.

doi:10.1039/c9cc06637c

Cited by 31 publications

(13 citation statements)

References 47 publications

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“…Catalytic transfer hydrogenations represent powerful and mild methods for the reduction of alkene functionality. − We believe that mechanistically similar catalytic transfer hydrodeuteration reactions hold much promise for making selectively deuterated small molecules. Until recently, selective catalytic hydrodeuteration reactions were rare and usually employed as mechanistic probes for alkyne semireductions. − A major challenge in catalytic transfer hydrodeuteration is discriminating between hydrogen (H) and deuterium (D) for selective incorporation into alkene functionality. , Catalytic alkene transfer hydrodeuteration reactions are now possible on a variety of alkenes. − Transition metal catalyzed transfer hydrodeuteration typically occurs in a regioselective manner for unactivated terminal alkenes, but selectivity is generally lower for terminal aryl alkene substrates (Scheme a). − Alternatively, using a boron catalyst, highly selective installation of deuterium into activated 1,1-diarylalkenes is possible, but with a limited alkene scope (Scheme b). , …”

Section: Introductionmentioning

confidence: 99%

Copper-Catalyzed Transfer Hydrodeuteration of Aryl Alkenes with Quantitative Isotopomer Purity Analysis by Molecular Rotational Resonance Spectroscopy

et al. 2021

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A copper-catalyzed alkene transfer hydrodeuteration reaction that selectively incorporates one hydrogen and one deuterium atom across an aryl alkene is described. The transfer hydrodeuteration protocol is selective across a variety of internal and terminal alkenes and is also demonstrated on an alkene-containing complex natural product analog. Beyond using 1H, 2H, and 13C NMR analysis to measure reaction selectivity, six transfer hydrodeuteration products were analyzed by molecular rotational resonance (MRR) spectroscopy. The application of MRR spectroscopy to the analysis of isotopic impurities in deuteration chemistry is further explored through a measurement methodology that is compatible with high-throughput sample analysis. In the first step, the MRR spectroscopy signatures of all isotopic variants accessible in the reaction chemistry are analyzed using a broadband chirped-pulse Fourier transform microwave spectrometer. With the signatures in hand, measurement scripts are created to quantitatively analyze the sample composition using a commercial cavity enhanced MRR spectrometer. The sample consumption is below 10 mg with analysis times on the order of 10 min using this instrumentboth representing order-of-magnitude reduction compared to broadband MRR spectroscopy. To date, these measurements represent the most precise spectroscopic determination of selectivity in a transfer hydrodeuteration reaction and confirm that product regioselectivity ratios of >140:1 are achievable under this mild protocol.

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Section: Introductionmentioning

confidence: 99%

Copper-Catalyzed Transfer Hydrodeuteration of Aryl Alkenes with Quantitative Isotopomer Purity Analysis by Molecular Rotational Resonance Spectroscopy

et al. 2021

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“…41 As a much more practical and ready available H 2 equivalent, it was recently shown that iso-propanol can also be employed in copper(I)-catalyzed transfer hydrogenations. 42 With a simple NHC/copper(I) complex 22 in catalytic amounts and NaOtBu as a basic additive, internal alkynes 20 could be converted into Z-alkenes 21 in moderate to very good yield (48-96%), while maintaining a high to excellent Z/E ratio (82:18 to 99:1) (Scheme 4, b). Remarkably, even under these drastic conditions, no overreduction to the corresponding alkane was observed, again underscoring the key influence of the NHC ligand on the chemoselectivity.…”

Section: Homogeneous Copper-catalyzed Transfer Hydrogenationsmentioning

confidence: 99%

Catch It If You Can: Copper-Catalyzed (Transfer) Hydrogenation Reactions and Coupling Reactions by Intercepting Reactive Intermediates Thereof

Brechmann

Teichert²

2020

Synthesis

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The key reactive intermediate of copper(I)-catalyzed alkyne semihydrogenations is a vinylcopper(I) complex. This intermediate can be exploited as a starting point for a variety of trapping reactions. In this manner, an alkyne semihydrogenation can be turned into a dihydrogen-mediated coupling reaction. Therefore, the development of copper-catalyzed (transfer) hydrogenation reactions is closely intertwined with the corresponding reductive trapping reactions. This short review highlights and conceptualizes the results in this area so far, with H2-mediated carbon–carbon and carbon–heteroatom bond-forming reactions emerging under both a transfer hydrogenation setting as well as with the direct use of H2. In all cases, highly selective catalysts are required that give rise to atom-economic multicomponent coupling reactions with rapidly rising molecular complexity. The coupling reactions are put into perspective by presenting the corresponding (transfer) hydrogenation processes first.1 Introduction: H2-Mediated C–C Bond-Forming Reactions2 Accessing Copper(I) Hydride Complexes as Key Reagents for Coupling Reactions; Requirements for Successful Trapping Reactions 3 Homogeneous Copper-Catalyzed Transfer Hydrogenations4 Trapping of Reactive Intermediates of Alkyne Transfer Semihydrogenation Reactions: First Steps Towards Hydrogenative Alkyne Functionalizations 5 Copper(I)-Catalyzed Alkyne Semihydrogenations6 Copper(I)-Catalyzed H2-Mediated Alkyne Functionalizations; Trapping of Reactive Intermediates from Catalytic Hydrogenations6.1 A Detour: Copper(I)-Catalyzed Allylic Reductions, Catalytic Generation of Hydride Nucleophiles from H2 6.2 Trapping with Allylic Electrophiles: A Copper(I)-Catalyzed Hydroallylation Reaction of Alkynes 6.3 Trapping with Aryl Iodides7 Conclusion

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“…To the best of our knowledge, non-noble metal-catalyzed methods for stereodivergent semi-reduction of alkynes using a CTH strategy are still insufficient, although a few copper-catalyzed semi-reduction of alkynes are known with equivalent amounts of base and limited substrate scope. 12 With our interest in the catalytic systems of transition-metal and diboron compounds, 13 we herein developed the Cu(OAc) 2 -catalyzed semi-reduction of alkynes under the aegis of B 2 pin 2 , and the absolute stereoselectivity of the products depended on the nature of substrates.…”

Section: Introductionmentioning

confidence: 99%

Substrate-Controlled Cu(OAc)₂-Catalyzed Stereoselective Semi-Reduction of Alkynes with MeOH as the Hydrogen Source

Huang

Wen

et al. 2021

ACS Omega

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A substrate-controlled stereoselective semi-reduction of alkynes with MeOH as the hydrogen source has been developed, and readily available Cu(OAc) 2 (copper acetate) is utilized as an optimal catalyst. The detailed investigation of the mechanism revealed distinct catalytic processes for the ( Z )- and ( E )-alkenes, respectively. As a result, a diversity of alkynes (including terminal, internal alkynes etc.) were compatible under the mild reaction conditions. Furthermore, the high proportion of deuterium in Z -alkenes (up to 96%) was obtained using d 4 -methanol as a solvent.

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Using alcohols as simple H₂-equivalents for copper-catalysed transfer semihydrogenations of alkynes

Abstract: Copper(i)/N-heterocyclic carbene complexes enable a catalytic transfer semihydrogenation of alkynes employing simple and readily available alcohols such as isopropanol.

Cited by 31 publications

References 47 publications

Copper-Catalyzed Transfer Hydrodeuteration of Aryl Alkenes with Quantitative Isotopomer Purity Analysis by Molecular Rotational Resonance Spectroscopy

Copper-Catalyzed Transfer Hydrodeuteration of Aryl Alkenes with Quantitative Isotopomer Purity Analysis by Molecular Rotational Resonance Spectroscopy

Catch It If You Can: Copper-Catalyzed (Transfer) Hydrogenation Reactions and Coupling Reactions by Intercepting Reactive Intermediates Thereof

Substrate-Controlled Cu(OAc)₂-Catalyzed Stereoselective Semi-Reduction of Alkynes with MeOH as the Hydrogen Source

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Using alcohols as simple H2-equivalents for copper-catalysed transfer semihydrogenations of alkynes

Abstract: Copper(i)/N-heterocyclic carbene complexes enable a catalytic transfer semihydrogenation of alkynes employing simple and readily available alcohols such as isopropanol.

Cited by 31 publications

References 47 publications

Copper-Catalyzed Transfer Hydrodeuteration of Aryl Alkenes with Quantitative Isotopomer Purity Analysis by Molecular Rotational Resonance Spectroscopy

Copper-Catalyzed Transfer Hydrodeuteration of Aryl Alkenes with Quantitative Isotopomer Purity Analysis by Molecular Rotational Resonance Spectroscopy

Catch It If You Can: Copper-Catalyzed (Transfer) Hydrogenation Reactions and Coupling Reactions by Intercepting Reactive Intermediates Thereof

Substrate-Controlled Cu(OAc)2-Catalyzed Stereoselective Semi-Reduction of Alkynes with MeOH as the Hydrogen Source

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Using alcohols as simple H₂-equivalents for copper-catalysed transfer semihydrogenations of alkynes

Substrate-Controlled Cu(OAc)₂-Catalyzed Stereoselective Semi-Reduction of Alkynes with MeOH as the Hydrogen Source