Generation of Axially Chiral Fluoroallenes through a Copper-Catalyzed Enantioselective β-Fluoride Elimination.
| Autor: | O'Connor TJ; Department of Chemistry, University of California, Berkeley, California 94720, United States., Mai BK; Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States., Nafie J; BioTools, Inc., 17546 Bee Line Highway, Jupiter, Florida 33458, United States., Liu P; Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States., Toste FD; Department of Chemistry, University of California, Berkeley, California 94720, United States. |
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| Jazyk: | angličtina |
| Zdroj: | Journal of the American Chemical Society [J Am Chem Soc] 2021 Sep 01; Vol. 143 (34), pp. 13759-13768. Date of Electronic Publication: 2021 Aug 16. |
| DOI: | 10.1021/jacs.1c05769 |
| Abstrakt: | Herein we report the copper-catalyzed silylation of propargylic difluorides to generate axially chiral, tetrasubstituted monofluoroallenes in both good yields (27 examples >80%) and enantioselectivities (82-98% ee). Compared to previously reported synthetic routes to axially chiral allenes (ACAs) from prochiral substrates, a mechanistically distinct reaction has been developed: the enantiodiscrimination between enantiotopic fluorides to set an axial stereocenter. DFT calculations and vibrational circular dichroism (VCD) suggest that β-fluoride elimination from an alkenyl copper intermediate likely proceeds through a syn -β-fluoride elimination pathway rather than an anti -elimination pathway. The effects of the C1-symmetric Josiphos-derived ligand on reactivity and enantioselectivity were investigated. Not only does this report showcase that alkenyl copper species (like their alkyl counterparts) can undergo β-fluoride elimination, but this elimination can be achieved in an enantioselective fashion. |
| Databáze: | MEDLINE |
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