Catalytic enantioselective conjugate addition of trimethylsilylacetylene to 2-cyclohexen-1-one

Organic Letters

Volumn 6, Issue 19, 2004, Pages 3385-3388

  Kwak, Young Shin ^a   Corey, E J ^a  

^a HARVARD UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

2 CYCLOHEXENONE; ACETYLENE DERIVATIVE; OXAZOLINE DERIVATIVE; TRIMETHYLSILYLACETYLENE; UNCLASSIFIED DRUG;

ADDITION REACTION; ARTICLE; CATALYSIS; CHEMICAL REACTION; CHIRALITY; CONJUGATION; ENANTIOSELECTIVITY; ROOM TEMPERATURE;

EID: 4644293034     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol048623v     Document Type: Article

References (19)

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13. The major contaminants in the crude product were formed by further reactions of the aluminum enolate 8 with 2-cyclohexenone. The yield can be improved (up to 68%) by slow addition of 2-cyclohexenone.
14. 2AlCl catalyzes the conjugate addition to form racemic β-ethynylated cyclohexanone. Any excess of TMSCCLi rapidly destroys the catalyst. Using these optimal conditions the rate of addition of 2-cyclohexanone is no longer critical and the ee of the product falls in the 82-88% ee range.
15. See: (a) Hayashi, T.; Yamasaki, K. Chem. Rev. 2003, 103, 2829. (b) Shintani, Y.; Takunaga, N.; Doi, H.; Hayashi, T. J. Am. Chem. Soc. 2004, 126, 6240.
16. See: (a) Hayashi, T.; Yamasaki, K. Chem. Rev. 2003, 103, 2829. (b) Shintani, Y.; Takunaga, N.; Doi, H.; Hayashi, T. J. Am. Chem. Soc. 2004, 126, 6240.
17. 4 and concentrated in vacuo, and the residue was purified by column chromatography (hexanes - ethyl acetate, 2:1) to provide 652 mg (1.68 mmol, 77%) of the (R,R)-cyano-bisoxazoline ent-2.
18. -1): 2359.8, 2340.4, 1624.3, 1521.0, 1088.6.
19. 3). The enantiomeric purity (82% ee) was determined by GC analysis using a chiral Cyclosil B column. (The oven temperature was 50°C for 8 min at start and increased by 2°C/min). The retention times of 10 and its enantiomer 3 were 47.225 and 47.516 min.