Mn-salen catalyzed asymmetric oxidation of enol derivatives

Tetrahedron Letters

Volumn 37, Issue 25, 1996, Pages 4389-4392

  Fukuda, Tsutomu ^a   Katsuki, Tsutomu ^a  

^a KYUSHU UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

ACETAL DERIVATIVE; ACETONITRILE; ALCOHOL DERIVATIVE; BENZENE DERIVATIVE; DICHLOROMETHANE; ETHER DERIVATIVE; KETONE DERIVATIVE; MANGANESE DERIVATIVE; OXIDIZING AGENT; SOLVENT;

ARTICLE; CATALYST; CHEMICAL REACTION; ENANTIOMER; EPOXIDATION; RACEMIC MIXTURE; STEREOCHEMISTRY;

EID: 0029884163     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/0040-4039(96)00858-1     Document Type: Article

References (17)

1. For a recent review of Mn-salen catalyzed epoxidation, see: a) Katsuki, T. J. Syth. Org. Chem., Jpn. 1995, 53, 940-951.
2. b) Katsuki, T. Coord. Chem. Rev. 1995, 140, 189-214.
3. c) Jacobsen, E. N. Asymmetric Catalytic Epoxidation of Unfunctionalized Olefins. In Catalytic Asymmetric Synthesis; Ojima I. Eds.; VCH publishers, Inc.: New York, 1993; pp. 159-202.
4. a) Sasaki, H.; Irie, R.; Hamada, T.; Suzuki, K.; Katsuki, T. Tetrahedron 1994, 50, 11827-11838.
5. b) Fukuda, T.; Irie, R.; Katsuki, T. Synlett 1995, 197-198.
6. Norrby, P.-O.; Linde, C.; Åkermark, B. J. Am. Chem. Soc. 1995, 117, 11035-11036.
7. Hamada, T.; Fukuda, T.; Imanishi, H.; Katsuki, T. Tetrahedron 1996, 52, 515-530.
8. Reddeppa Reddy, D.; Thornton, E. R. J. Chem. Soc., Chem. Commun. 1992, 172-173.
9. Chang, S.; Heid, R. M.; Jacobsen, E. N. Tetrahedron Lett. 1994, 35, 669-672.
10. For example, the optical purity of 2-hydroxytetralone decreased on standing under the reaction conditions.
11. Irie, R.; Ito, Y.; Katsuki, T. Synlett 1991, 265-266.
12. 1H NMR analysis of the corresponding acetates. The signal of the methoxy group of 4 appears at lower field than that of 5 due to the anisotropic effect of the vicinal C-O bond.
13. This mixture is not a thermodynamic but a kinetic product. This is supported by the result that oxidation of 1-ethoxy-1-cyclohexane in methanol gave a 1: 9 mixture of 4 and 5.
14. The enantiomeric excesses of 4 and 5 were determined as described in Scheme 3 by HPLC analysis using DAICEL CHIRALCEL OF (hexane/i-PrOH = 600/1 and 400/1, respectively) after Chromatographic separation (SiO2, hexane/ethyl acetate =19/1). Configuration of the carbinol carbon in 4 and 5 was determined as described in the footnote f to Table 1.
15. Involvement of the cationic rearrangement has been proposed for metalloporphyrin and Cr-salen catalyzed epoxidation. Meunier, B. Chem. Rev. 1992, 92, 1411-1456.
16. Although we have proposed that the diastereoselective homolytic cleavage of the Mn-C bond of the metallaoxetane intermediate explains the stereochemistry observed in the epoxidation of simple olefins (ref. 4), the diastereoselective heterolytic cleavage of the Mn-C bond equally explains the stereochemistry of the epoxidation and it is well known that the cation at the carbon bearing an alkoxy group is strongly stabilized by the lone pair electrons of the oxygen atom.
17. Heterolysis of the O-M bond has been proposed by Norrby et al. (ref. 3).