First principles (DFT) characterization of RhI/dppp-catalyzed C-H activation by tandem 1,2-addition/1,4-Rh shift reactions of norbornene to phenylboronic acid
The C-H activation in the tandem, “merry-go-round”, [(dppp)Rh]-catalyzed (dppp=1,3-bis(diphenylphosphino)propane), four-fold addition of norborene to PhB(OH)2 has been postulated to occur by a C(alkyl)-H oxidative addition to square-pyramidal RhIII-H species, which in turn undergoes a C(aryl)-H redu...
| Main Authors: | , , , , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
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2014
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| Online Access: | https://hdl.handle.net/10356/103155 http://hdl.handle.net/10220/24442 |
| _version_ | 1826120944464166912 |
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| author | Kantchev , Eric Assen B. Pangestu, Surya R. Zhou, Feng Sullivan, Michael B. Su, Hai-Bin |
| author2 | School of Materials Science & Engineering |
| author_facet | School of Materials Science & Engineering Kantchev , Eric Assen B. Pangestu, Surya R. Zhou, Feng Sullivan, Michael B. Su, Hai-Bin |
| author_sort | Kantchev , Eric Assen B. |
| collection | NTU |
| description | The C-H activation in the tandem, “merry-go-round”, [(dppp)Rh]-catalyzed (dppp=1,3-bis(diphenylphosphino)propane), four-fold addition of norborene to PhB(OH)2 has been postulated to occur by a C(alkyl)-H oxidative addition to square-pyramidal RhIII-H species, which in turn undergoes a C(aryl)-H reductive elimination. Our DFT calculations confirm the RhI/RhIII mechanism. At the IEFPCM(toluene, 373.15 K)/PBE0/DGDZVP level of theory, the oxidative addition barrier was calculated to be 12.9 kcal mol−1, and that of reductive elimination was 5.0 kcal mol−1. The observed selectivity of the reaction correlates well with the relative energy barriers of the cycle steps. The higher barrier (20.9 kcal mol−1) for norbornyl–Rh protonation ensures that the reaction is steered towards the 1,4-shift (total barrier of 16.3 kcal mol−1), acting as an equilibration shuttle. The carborhodation (13.2 kcal mol−1) proceeds through a lower barrier than the protonation (16.7 kcal mol−1) of the rearranged aryl–Rh species in the absence of o- or m-substituents, ensuring multiple carborhodations take place. However, for 2,5-dimethylphenyl, which was used as a model substrate, the barrier for carborhodation is increased to 19.4 kcal mol−1, explaining the observed termination of the reaction at 1,2,3,4-tetra(exo-norborn-2-yl)benzene. Finally, calculations with (Z)-2-butene gave a carborhodation barrier of 20.2 kcal mol−1, suggesting that carborhodation of non-strained, open-chain substrates would be disfavored relative to protonation. |
| first_indexed | 2024-10-01T05:24:42Z |
| format | Journal Article |
| id | ntu-10356/103155 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T05:24:42Z |
| publishDate | 2014 |
| record_format | dspace |
| spelling | ntu-10356/1031552020-06-01T10:13:35Z First principles (DFT) characterization of RhI/dppp-catalyzed C-H activation by tandem 1,2-addition/1,4-Rh shift reactions of norbornene to phenylboronic acid Kantchev , Eric Assen B. Pangestu, Surya R. Zhou, Feng Sullivan, Michael B. Su, Hai-Bin School of Materials Science & Engineering DRNTU::Science::Chemistry The C-H activation in the tandem, “merry-go-round”, [(dppp)Rh]-catalyzed (dppp=1,3-bis(diphenylphosphino)propane), four-fold addition of norborene to PhB(OH)2 has been postulated to occur by a C(alkyl)-H oxidative addition to square-pyramidal RhIII-H species, which in turn undergoes a C(aryl)-H reductive elimination. Our DFT calculations confirm the RhI/RhIII mechanism. At the IEFPCM(toluene, 373.15 K)/PBE0/DGDZVP level of theory, the oxidative addition barrier was calculated to be 12.9 kcal mol−1, and that of reductive elimination was 5.0 kcal mol−1. The observed selectivity of the reaction correlates well with the relative energy barriers of the cycle steps. The higher barrier (20.9 kcal mol−1) for norbornyl–Rh protonation ensures that the reaction is steered towards the 1,4-shift (total barrier of 16.3 kcal mol−1), acting as an equilibration shuttle. The carborhodation (13.2 kcal mol−1) proceeds through a lower barrier than the protonation (16.7 kcal mol−1) of the rearranged aryl–Rh species in the absence of o- or m-substituents, ensuring multiple carborhodations take place. However, for 2,5-dimethylphenyl, which was used as a model substrate, the barrier for carborhodation is increased to 19.4 kcal mol−1, explaining the observed termination of the reaction at 1,2,3,4-tetra(exo-norborn-2-yl)benzene. Finally, calculations with (Z)-2-butene gave a carborhodation barrier of 20.2 kcal mol−1, suggesting that carborhodation of non-strained, open-chain substrates would be disfavored relative to protonation. 2014-12-11T08:18:41Z 2019-12-06T21:06:34Z 2014-12-11T08:18:41Z 2019-12-06T21:06:34Z 2014 2014 Journal Article Kantchev , E. A. B., Pangestu, S. R., Zhou, F., Sullivan, M. B., & Su, H.-B. (2014). First principles (DFT) characterization of RhI/dppp-catalyzed C-H activation by tandem 1,2-addition/1,4-Rh shift reactions of norbornene to phenylboronic acid. Chemistry - A European journal, 20(47), 15625-15634. 0947-6539 https://hdl.handle.net/10356/103155 http://hdl.handle.net/10220/24442 10.1002/chem.201402988 en Chemistry - A European journal © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. |
| spellingShingle | DRNTU::Science::Chemistry Kantchev , Eric Assen B. Pangestu, Surya R. Zhou, Feng Sullivan, Michael B. Su, Hai-Bin First principles (DFT) characterization of RhI/dppp-catalyzed C-H activation by tandem 1,2-addition/1,4-Rh shift reactions of norbornene to phenylboronic acid |
| title | First principles (DFT) characterization of RhI/dppp-catalyzed C-H activation by tandem 1,2-addition/1,4-Rh shift reactions of norbornene to phenylboronic acid |
| title_full | First principles (DFT) characterization of RhI/dppp-catalyzed C-H activation by tandem 1,2-addition/1,4-Rh shift reactions of norbornene to phenylboronic acid |
| title_fullStr | First principles (DFT) characterization of RhI/dppp-catalyzed C-H activation by tandem 1,2-addition/1,4-Rh shift reactions of norbornene to phenylboronic acid |
| title_full_unstemmed | First principles (DFT) characterization of RhI/dppp-catalyzed C-H activation by tandem 1,2-addition/1,4-Rh shift reactions of norbornene to phenylboronic acid |
| title_short | First principles (DFT) characterization of RhI/dppp-catalyzed C-H activation by tandem 1,2-addition/1,4-Rh shift reactions of norbornene to phenylboronic acid |
| title_sort | first principles dft characterization of rhi dppp catalyzed c h activation by tandem 1 2 addition 1 4 rh shift reactions of norbornene to phenylboronic acid |
| topic | DRNTU::Science::Chemistry |
| url | https://hdl.handle.net/10356/103155 http://hdl.handle.net/10220/24442 |
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