Rhodium carbenoid-initiated claisen rearrangement: Scope and mechanistic observations

Organic Letters

Volumn 1, Issue 3, 1999, Pages 371-374

  Wood, John L ^a   Moniz, George A ^a  

^a YALE UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

KETONE; RHODIUM;

ARTICLE; CHEMISTRY; SYNTHESIS; X RAY CRYSTALLOGRAPHY;

CRYSTALLOGRAPHY, X-RAY; KETONES; RHODIUM;

EID: 0033549658     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol990697x     Document Type: Article

References (24)

1. Wood, J. L.; Moniz, G. A.; Pflum, D. A.; Stoltz, B. M.; Holubec, A. A.; Dietrich, H.-J. J. Am. Chem. Soc. 1999, 121, 1748.
2. The highly selective formation of a Z-enol suggests the reaction proceeds via intramolecular proton transfer to oxygen (i.e., i → ii). (equation presented)
3. For recent reviews on the chemistry of enols, see: (a) Hart, H. Chem. Rev. 1979, 79, 515.
4. (b) Kresge, A. J. CHEMTECH 1986, 16, 250.
5. (c) Capon, B.; Guo, B.; Kwok, F. C.; Siddhanta, A. K.; Zucco, C. Acc. Chem. Res. 1988, 21, 135.
6. (d) Rappoport, Z.; Biali, S. E. Acc. Chem. Res. 1988, 21, 442.
7. (e) Kresge, A. J. Acc. Chem. Res. 1990, 23, 43.
8. McGarrity, J. F.; Pinkerton, A. A.; Schwartzenbach, D.; Flack, H. D. Angew. Chem., Int. Ed. Engl. 1983, 22, 405.
9. As reported by McGarrity (ref 4), 6 can be isolated via crystallization or converted to several derivatives. To confirm the stability of the enol geometry under the conditions of derivatization, we prepared the corresponding acetate (ii) and established the structure by single-crystal X-ray analysis (see Supporting Information). (equation presented)
10. A study of the tautomerization of this enol has recently been reported, see: Jefferson, E. A.; Kresge, A. J.; Wu, Z. Can. J. Chem. 1998, 76, 1284.
11. (a) Our interest in this possibility derived from the known Lewis acidity of some Rh(II) catalysts, see: Doyle, M. P. Chem. Rev. 1986, 86, 919. For a leading reference describing Lewis acid promotion of the Claisen rearrangement, see: Lutz, R. P. Chem. Rev. 1984, 84, 205.
12. (a) Our interest in this possibility derived from the known Lewis acidity of some Rh(II) catalysts, see: Doyle, M. P. Chem. Rev. 1986, 86, 919. For a leading reference describing Lewis acid promotion of the Claisen rearrangement, see: Lutz, R. P. Chem. Rev. 1984, 84, 205.
13. 3N resulted in rapid tautomerization of the intermediate enol to the α-allyloxy ketone (i.e., the formal O-H insertion product).
14. (a) Yoo, H. Y.; Houk, K. N. J. Am. Chem. Soc. 1997, 119, 2877.
15. (b) We thank Professor Houk for providing unpublished results regarding the Z-enol 14.
16. Ziegler, F. E.; Chem. Rev. 1988, 88, 1423. Wipf, P. In Comprehensive Organic Syntheses; Trost, B. M., Fleming, I., Eds.; Pergamon Press: New York, 1991; Vol. 5, p 827 and references therein.
17. Ziegler, F. E.; Chem. Rev. 1988, 88, 1423. Wipf, P. In Comprehensive Organic Syntheses; Trost, B. M., Fleming, I., Eds.; Pergamon Press: New York, 1991; Vol. 5, p 827 and references therein.
18. A similar effect was noted by Koreeda in the anionic variant of this reaction, see: Koreeda, M.; Luengo, J. I. J. Am. Chem. Soc. 1985, 107, 5572.
19. The delicate balance between ketonization and rearrangement is further illustrated by a deuterium isotope study wherein allyl alcohol OD was found to combine with 1 and funish a 6:1 ratio of Claisen/OD insertion products.
20. 13C (125 MHz) spectra, as well as appropriate parent ion identification by high-resolution mass spectrometry.
21. For a recent application of reactive enols in synthesis, see: Wood, J. L.; Holubec, A. A.; Stoltz, B. M.; Weiss, M. M.; Dixon, J. A.; Doan, B. D.; Shamji, M. F.; Chen, J. M.; Heffron, T. P. J. Am. Chem. Soc. In Press.
22. For a review of pericyclic reactions of acetylenic compounds, see: Viola, A.; Collins, J. J.; Filipp, N. Tetrahedron 1981, 37, 3765.
23. For a similar application, see the preceding Letter in this issue (Jung, M. E.; Pontillo, J. Org. Lett. 1999, 1, 367). We thank Professor Jung for sharing this information prior to publication.
24. 4 in refluxing benzene for 3 h.