Homogeneous Hydrogenation of Alkynes and Dienes

Elsevier, C.J.; Kluwer, Alexander M.

doi:10.1002/9783527619382.ch14

Cited by 46 publications

(62 citation statements)

References 90 publications

(151 reference statements)

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“…In order to follow the reaction and extract kinetic parameters using dDNP enhanced 13 C NMR spectroscopy the substrate should contain at least one carbon atom with a T 1 long enough to allow collecting NMR spectra with signals from both the substrate and the product. Furthermore the chemical shift of the carbon atom with long T 1 should change enough during the reaction to allow discrimination between substrate and product.…”

Section: Introductionmentioning

confidence: 99%

“…They are close to the reaction site on the molecule and are likely to participate in the coordination of the substrate to the Rh center. 13 C NMR has sufficient resolution to allow peaks of substrate and product to be well separated in the spectrum. Enrichment with 13 Instrumentation:…”

Section: Introductionmentioning

confidence: 99%

“…13 C NMR has sufficient resolution to allow peaks of substrate and product to be well separated in the spectrum. Enrichment with 13 Instrumentation:…”

Section: Introductionmentioning

confidence: 99%

“…Hyperpolarization was achieved using an Oxford Instruments HyperSense polarizer working at 3.35 T and 1.3 K. 13 C NMR spectra were recorded on a Varian Inova 400 MHz spectrometer equipped with a 10 mm broadband probe. Selected experiments were performed on the same spectrometer in a Shigemi tube using a 5 mm broadband probe.…”

Section: Introductionmentioning

confidence: 99%

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Real-Time Detection of Intermediates in Rhodium-Catalyzed Hydrogenation of Alkynes and Alkenes by Dissolution DNP

et al. 2019

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…13 C NMR has sufficient resolution to allow peaks of substrate and product to be well separated in the spectrum. Enrichment with 13 Instrumentation:…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Real-Time Detection of Intermediates in Rhodium-Catalyzed Hydrogenation of Alkynes and Alkenes by Dissolution DNP

et al. 2019

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“…The semihydrogenation of alkynes is one of the most reliable methods with which to selectively synthesize Z ‐alkenes,41,47 which are part of many biologically and pharmaceutically active compounds. The alkenes are produced both as bulk and as specialty compounds 41,48–50.…”

Section: Introductionmentioning

confidence: 99%

Allylpalladium(II) Histidylidene Complexes and Their Application in Z‐Selective Transfer Semihydrogenation of Alkynes

et al. 2015

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We have studied the use of amino acid histidine as a precursor for N-heterocyclic carbene (NHC) ligands. This natural amino acid possesses an imidazole substituent, which makes it an interesting NHC precursor that contains both an acid and an amino functionality. These functionalities may be used for further tuning of NHC complexes. We have developed routes for the synthesis of symmetric and dissymmetric alkyl, benzyl, and aryl-substituted histidinium salts.[a] Molecular Scheme 3. Synthesis of symmetrically substituted benzylic histidinium bromides. The Cyclic Urea ApproachSubsequently, we employed the cyclic urea approach, which allows the synthesis of dissymmetrically substituted histidinium salts and further tuning of the properties of the NHC metal complex. This is not straightforward because histidine has two tautomeric forms, which means that the δ-and the ε-nitrogen of the imidazole possess both imine and amine character (compound 4, Scheme 5). [20] Therefore, mixtures of regioisomers are obtained when the imidazole is reacted with one equivalent of an electrophile. To obtain the desired dissymmetrically substituted histidinium salts, we applied a route based on the report by Hodges and Chivikas, [17] and was improved by Brégeon et al. [30] (Scheme 4). Scheme 4. The cyclic urea route toward dissymmetrically substituted histidinium salts.This cyclic urea route induces regioselectivity because only the six-membered cyclic urea 5 can be formed. The second nitrogen atom can then be functionalized selectively through nucleophilic substitution. Subsequently, the R 1functionalized urea compounds can be ring-opened by reaction with an alcohol, which liberates the δ-nitrogen atom of the imidazole, and provides a carbamate-protected amine. The use of tBuOH affords the Boc-protected histidine, Eur. J. Inorg. Chem. 2015, 982-996

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Chemical Reaction Monitoring using Zero‐Field Nuclear Magnetic Resonance Enables Study of Heterogeneous Samples in Metal Containers

et al. 2020

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We demonstrate that heterogeneous/biphasic chemical reactions can be monitored with high spectroscopic resolution using zero‐field nuclear magnetic resonance spectroscopy. This is possible because magnetic susceptibility broadening is negligible at ultralow magnetic fields. We show the two‐step hydrogenation of dimethyl acetylenedicarboxylate with para‐enriched hydrogen gas in conventional glass NMR tubes, as well as in a titanium tube. The low frequency zero‐field NMR signals ensure that there is no significant signal attenuation arising from shielding by the electrically conductive sample container. This method paves the way for in situ monitoring of reactions in complex heterogeneous multiphase systems and in reactors made of conductive materials while maintaining resolution and chemical specificity.

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Homogeneous Hydrogenation of Alkynes and Dienes

Cited by 46 publications

References 90 publications

Real-Time Detection of Intermediates in Rhodium-Catalyzed Hydrogenation of Alkynes and Alkenes by Dissolution DNP

Real-Time Detection of Intermediates in Rhodium-Catalyzed Hydrogenation of Alkynes and Alkenes by Dissolution DNP

Allylpalladium(II) Histidylidene Complexes and Their Application in Z‐Selective Transfer Semihydrogenation of Alkynes

Chemical Reaction Monitoring using Zero‐Field Nuclear Magnetic Resonance Enables Study of Heterogeneous Samples in Metal Containers

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