Chiral Discrimination in Rhodium(I) Catalysis by 2,5-Disubstituted 1,3 a,4,6 a -Tetrahydropenatalene Ligands -More Than Just a Twist of the Olefins?
(2018) In ACS Omega 3(3). p.3622-3630- Abstract
Chiral dienes are useful ligands in a number of asymmetric transition-metal-catalyzed reactions. Here, we evaluate the efficiency of 2,5-disubstituted 1,3a,4,6a-tetrahydropentalenes as ligands to rhodium(I). 2,5-Dibenzyl and diphenyl tetrahydropentalenes were synthesized in two steps and resolved, either chromatographically, or through fractional crystallization of diastereomeric rhodium(I) salts. When evaluated in a 1,4-arylation reaction, the 2,5-dibenzyl ligand gave up to 99% ee. The use of a well-defined rhodium complex as catalyst, Cs2CO3 as the base, and toluene/water as solvent was found to have a pronounced beneficial effect on the selectivity of the reaction. The homologous 2,5-diphenyl ligand on the other... (More)
Chiral dienes are useful ligands in a number of asymmetric transition-metal-catalyzed reactions. Here, we evaluate the efficiency of 2,5-disubstituted 1,3a,4,6a-tetrahydropentalenes as ligands to rhodium(I). 2,5-Dibenzyl and diphenyl tetrahydropentalenes were synthesized in two steps and resolved, either chromatographically, or through fractional crystallization of diastereomeric rhodium(I) salts. When evaluated in a 1,4-arylation reaction, the 2,5-dibenzyl ligand gave up to 99% ee. The use of a well-defined rhodium complex as catalyst, Cs2CO3 as the base, and toluene/water as solvent was found to have a pronounced beneficial effect on the selectivity of the reaction. The homologous 2,5-diphenyl ligand on the other hand proved to be highly prone to racemization/loss of chirality during catalysis. Control experiments reveal that this rearrangement proceeds via a rhodium-mediated 1,3-hydride shift. Implications for ligand design and catalysis are discussed.
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- author
- Melcher, Michaela Christina LU ; Rolim Alves Da Silva, Bianca ; Ivšić, Trpimir LU and Strand, Daniel LU
- organization
- publishing date
- 2018-01-01
- type
- Contribution to journal
- publication status
- published
- subject
- in
- ACS Omega
- volume
- 3
- issue
- 3
- pages
- 9 pages
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- scopus:85044836487
- ISSN
- 2470-1343
- DOI
- 10.1021/acsomega.8b00127
- language
- English
- LU publication?
- yes
- id
- fe0d0909-1d98-419b-be8a-4a1eda6bb33b
- date added to LUP
- 2018-04-16 14:17:45
- date last changed
- 2022-04-25 06:53:23
@article{fe0d0909-1d98-419b-be8a-4a1eda6bb33b, abstract = {{<p>Chiral dienes are useful ligands in a number of asymmetric transition-metal-catalyzed reactions. Here, we evaluate the efficiency of 2,5-disubstituted 1,3a,4,6a-tetrahydropentalenes as ligands to rhodium(I). 2,5-Dibenzyl and diphenyl tetrahydropentalenes were synthesized in two steps and resolved, either chromatographically, or through fractional crystallization of diastereomeric rhodium(I) salts. When evaluated in a 1,4-arylation reaction, the 2,5-dibenzyl ligand gave up to 99% ee. The use of a well-defined rhodium complex as catalyst, Cs<sub>2</sub>CO<sub>3</sub> as the base, and toluene/water as solvent was found to have a pronounced beneficial effect on the selectivity of the reaction. The homologous 2,5-diphenyl ligand on the other hand proved to be highly prone to racemization/loss of chirality during catalysis. Control experiments reveal that this rearrangement proceeds via a rhodium-mediated 1,3-hydride shift. Implications for ligand design and catalysis are discussed.</p>}}, author = {{Melcher, Michaela Christina and Rolim Alves Da Silva, Bianca and Ivšić, Trpimir and Strand, Daniel}}, issn = {{2470-1343}}, language = {{eng}}, month = {{01}}, number = {{3}}, pages = {{3622--3630}}, publisher = {{The American Chemical Society (ACS)}}, series = {{ACS Omega}}, title = {{Chiral Discrimination in Rhodium(I) Catalysis by 2,5-Disubstituted 1,3 a,4,6 a -Tetrahydropenatalene Ligands -More Than Just a Twist of the Olefins?}}, url = {{http://dx.doi.org/10.1021/acsomega.8b00127}}, doi = {{10.1021/acsomega.8b00127}}, volume = {{3}}, year = {{2018}}, }