Enantioselective Synthesis of Alkyne-Substituted Quaternary Carbon Stereogenic Centers through NHC−Cu-Catalyzed Allylic Substitution Reactions with (i-Bu)2(Alkynyl)aluminum Reagents
| Autor: | Amir H. Hoveyda, Fang Gao, Jennifer A. Dabrowski |
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| Rok vydání: | 2011 |
| Předmět: |
Models
Molecular Allylic rearrangement Alkyne Crystallography X-Ray Biochemistry Chemical synthesis Article Catalysis Stereocenter chemistry.chemical_compound Colloid and Surface Chemistry Heterocyclic Compounds Organometallic Compounds Organic chemistry Alkyl chemistry.chemical_classification Substitution reaction Molecular Structure Aryl Enantioselective synthesis Stereoisomerism General Chemistry chemistry Alkynes Methane Copper Aluminum |
| Zdroj: | Journal of the American Chemical Society. 133:4778-4781 |
| ISSN: | 1520-5126 0002-7863 |
| Popis: | A catalytic enantioselective method for the formation of alkyne-substituted all-carbon quaternary stereogenic centers is reported. Additions of alkynylaluminums to alkyl-, aryl-, carboxylic ester-, or silyl-substituted allylic phosphates are promoted by 1.0-5.0 mol % loadings of NHC-Cu complexes derived from air-stable and commercially available CuCl(2)·2H(2)O. The requisite Al-based reagents are prepared through treatment of the corresponding aryl-, heteroaryl-, alkyl-, or alkenyl-substituted terminal alkynes with diisobutylaluminum hydride in the presence of 5.0 mol % Et(3)N at ambient temperature. The desired 1,4-enynes are obtained in up to 98% yield and99:1 enantiomeric ratio. Selected Au-catalyzed cyclizations involving the alkyne unit of the enantiomerically enriched products are presented as a demonstration of the method's utility in chemical synthesis. |
| Databáze: | OpenAIRE |
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