Oxidation of α-alkylbenzyl alcohols catalysed by 5,10,15,20- tetrakis(pentafluorophenyl)porphyrin iron(III) chloride. Competition between C-H and C-C bond cleavage

Tetrahedron Letters

Volumn 39, Issue 26, 1998, Pages 4711-4714

  Baciocchi, Enrico ^a   Belvedere, Sandro ^a   Bietti, Massimo ^a,b  

^a SAPIENZA UNIVERSITY OF ROME   (Italy)

^b UNIVERSITY OF ROME TOR VERGATA   (Italy)

Author keywords

[No Author keywords available]

Indexed keywords

BENZALDEHYDE DERIVATIVE; BENZYL ALCOHOL DERIVATIVE; HYDROGEN; IODOBENZENE; IRON COMPLEX; KETONE DERIVATIVE; PORPHYRIN DERIVATIVE;

ARTICLE; CATALYSIS; CHEMICAL BOND; CHEMICAL REACTION; COMPLEX FORMATION; DECOMPOSITION; OXIDATION;

EID: 0032566022     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(98)00863-6     Document Type: Article

References (16)

1. 1. (a) Cytochrome P-450: Structure, Mechanism and Biochemistry, 2nd ed.; Ortiz de Montellano, P. R., Ed.; Plenum Press, New York, 1995.
2. (b) Metalloporphyrin Catalyzed Oxidations; Montanari, F. Casella, L. Eds.; Kluwer Academic Publishers, Dordrecht, 1994.
3. (c) Metalloporphyrins in Catalytic Oxidations; Sheldon R. A., Ed.; Marcel Dekker, New York, 1994.
4. (d) Meunier, B. Chem. Rev. 1992, 92, 1411
5. 2. Traylor, T. G.; Hill, K. W.; Farm, W.-P.; Tsuchiya, S.; Dunlap, B. E. J. Am. Chem. Soc. 1992, 114, 1308.
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7. 4. Wietzerbin, K.; Meunier, B.; Bernadou, J. Chem. Commun. 1997, 2321.
8. 5. Baciocchi, E.; Belvedere, S.; Bietti, M.; Lanzalunga, O. Eur. J. Org. Chem. 1998, 1, 299.
9. 6. In the case of compounds 8 and 9, no fragmentation products were detected but only the ketone and the corresponding alcohol (presumably formed by side-chain O-demethylation of the substrate), together with small amounts of ring oxygenated products. On the basis of the absence of benzaldehyde in the reaction mixture it can be excluded that the ketone derives by oxidation of the first formed alcohol.
10. -5 mol).
11. 9 A larger difference can be expected with a tertiary benzylic carbon.
12. 9. McMillen, D. F.; Golden, D. M. Ann. Rev. Phys. Chem. 1982, 33, 493.
13. 10. See ref. 1 (a), page 279.
14. 11. Okamoto, T.; Sasaki, K.; Oka, S. J. Am. Chem. Soc. 1988, 110, 1187.
15. 12. Young, L. B.; Trahanovsky, W. S. J. Am. Chem. Soc. 1969, 97, 5060.
16. +-Fe(IV)=O with the alcoholic OH group forming an alkoxyl radical which undergoes a β-fragmentation reaction, as suggested by Meunier for the biomimetic oxidation of tertiary alcohols, might also explain the formation of C-C bond cleavage products. However, we feel that this possibility is unlikely in the case of secondary alcohols as the O-H bond dissociation energy is much higher than that of a benzylic C-H bond.