| Autor: |
Lee YJ; Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA., Schrock RR, Hoveyda AH |
| Jazyk: |
angličtina |
| Zdroj: |
Journal of the American Chemical Society [J Am Chem Soc] 2009 Aug 05; Vol. 131 (30), pp. 10652-61. |
| DOI: |
10.1021/ja904098h |
| Abstrakt: |
Stereogenic-at-Mo monoalkoxide and monoaryloxide complexes promote enyne ring-closing metathesis (RCM) reactions, affording the corresponding endo products with high selectivity (typically >98:<2 endo:exo). All catalysts can be prepared and used in situ. Five-, six-, and seven-membered rings are obtained through reactions with enyne substrates that bear all-carbon tethers as well as those that contain heteroatom substituents. The newly developed catalytic protocols complement the related exo-selective Ru-catalyzed processes. In cases where Ru-based complexes deliver exo and endo products nondiscriminately, such as when tetrasubstituted cyclic alkenes are generated, Mo-catalyzed reactions afford the endo product exclusively. The efficiency of synthesis of N- and O-containing endo diene heterocycles can be improved significantly through structural modification of Mo catalysts. The modularity of Mo-based monopyrrolides is thus exploited in the identification of the most effective catalyst variants. Through alteration of O-based monodentate ligands, catalysts have been identified that promote enyne RCM with improved efficiency. The structural attributes of three Mo complexes are elucidated through X-ray crystallography. The first examples of catalytic enantioselective enyne RCM reactions are reported (up to 98:2 enantiomer ratio and >98% endo). |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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