Low-temperature n-butyllithium-induced rearrangement of allyl 1,1-dichlorovinyl ethers

Organic Letters

Volumn 8, Issue 3, 2006, Pages 451-454

  Christopher, Aaron ^a   Brandes, Dahniel ^a   Kelly, Stephen ^a   Minehan, Thomas ^a  

^a CALIFORNIA STATE UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 32644435637     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol052685j     Document Type: Article

References (36)

1. For reviews of the Claisen Rearrangement, see: (a) Ziegler, F. E. Chem. Rev. 1988, 88, 1423.
2. (b) Ito, H.; Taguchi, T. Chem. Soc. Rev. 1999, 28, 43.
3. (c) Hiersemann, M.; Abraham, L. Eur. J. Org. Chem. 2002, 1461.
4. (d) Nubbemeyer, U. Synthesis 2003, 961.
5. (a) Wipf, P. Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon: Oxford, 1991; Vol. 5, p 827.
6. (b) Wilson, S. R. Organic Reactions; John Wiley & Sons: New York, 1993; Vol. 43, p 93.
7. (c) Paquette, L. A. Tetrahedron 1997, 53, 13971.
8. Olsman, H.; Graveland, A.; Arens, J. F. Rec. Trav. Chim. Pays-Bas 1964, 83, 301.
9. Wunderli, A.; Zsindely, J.; Hansen, H. J.; Schmid, H. Chimia 1972, 26, 643.
10. Brandesma, L.; Bos, H. J.; Arens, J. F. In The Chemistry of Acetylenes; Viehe, H. G., Ed.; Marcel Dekker: New York, 1969; pp 751-860.
11. For a review of methods for the synthesis of ynol ethers, see: Stang, P. J.; Zhdankin, V. V. The Chemistry of Triple-Bonded Functional Groups; Patai, S., Ed.; John Wiley & Sons: New York, New York, 1994; Chapter 19.
12. (a) Smithers, R. H. Synthesis 1985, 556.
13. (b) Himbert, G.; Loffler, A. Synthesis 1992, 495.
14. Moyano, A.; Charbonnier, F.; Greene, A. E. J. Org. Chem. 1987, 52, 2, 2919.
15. Only trace amounts of 1,2-dichlorovinyl ethers were formed using the Greene protocol, with starting allylic alcohols recovered in >90% yield from the reaction mixture.
16. Huffman, C. W. J. Org. Chem. 1958, 23, 727.
17. The allyl 1,1-dichlorovinyl ethers prepared were stable at room temperature and at 60 °C in THF under the conditions for their formation from the corresponding formate esters. The [3,3]-sigmatropic rearrangement of allyl 1,1-dichlorovinyl ethers at temperatures >100 °C has been described: Morimoto, T.; Sekiya, M. Synthesis 1981, 308.
18. Bruckner, D. Synlett 2000, 1402.
19. See also: Lakhrissi, M.; Chapleur, Y. J. Org. Chem. 1994, 59, 5752.
20. (a) The use of LDA instead of n-BuLi under the same reaction conditions failed to afford rearrangement products.
21. (b) It was subsequently found that warming the reaction to -40 °C before quench with ethanol was unnecessary; high yields of rearranged products 3 are consistently obtained after stirring the reaction mixture for 15-30 min at -78 °C followed by ethanol quench and warming to room temperature (vide infra).
22. A similar result was noted by Bruckner in an attempted synthesis of alkynylsulfonamides from dibromovinyl sulfonamides; see ref 12.
23. Treatment of 2g with n-BuLi at -78 °C gave a dark-colored solution (presumably due to formation of a highly delocalized carbanion), which upon ethanol quench furnished a cis/trans mixture of monodechlorination products.
24. 4/THF (see supporting info for details). cis-Carveol was synthesized by stereoselective reduction of (R)-(-)-carvone: Mowery, M. E.; DeShong, P. J. Org. Chem. 1999, 64, 1684.
25. trans-Carveol was prepared by Mitsunobu inversion/hydrolysis of cu-carveol: Uesaka, N.; Saitoh, F.; Mori, M.; Shibasaki, M.; Okamura, K.; Date, T. J. Org. Chem. 1994, 59, 5633.
26. 1H NMR data for 6a and 6b matched those reported by Bermejo: Rico, R.; Zapico, J.; Bermejo, F.; Sanni, S. B.; Garcia-Granda, S. Tetrahedron: Asymmetry 1998, 9, 293.
27. 5′, thus confirming the assignment of the β stereochemistry shown above. See the Supporting Information for details. For a discussion of the stereochemical assignment of 2,3-unsaturated C-glycosides, see: Brakta, M.; Farr, R. N.; Chaguir, B.; Massiot, G.; Lavaud, C.; Anderson, W. R.; Sinou, D.; Daves, G. D. J. Org. Chem. 1993, 58, 2992.
28. Based on our proposed mechanism (Scheme 5, vide infra), we suggest that this unstable species present at low temperature is an allyl alkynyl ether (e.g., 15a, Scheme 5).
29. Trapping the anionic intermediate with benzaldehyde (1.5 equiv, 1 h, -78 °C, followed by 1.5 equiv of TMSCl, -78 to +25 °C) was also successful, giving rise to a mixture of aldol diastereomers.
30. 1H NMR spectral data with literature values: Tamaru, Y.; Furukawa, Y.; Mizutani, M.; Kitao, O.; Yoshida, Z. J. Org. Chem. 1983, 48, 3631.
31. Attempts to trap the anionic intermediate by reaction with acetyl chloride, tosyl chloride, ethyl chloroformate, TIPS-Cl, or TBDPS-Cl led only to a complex mixture of unidentifiable products.
32. See refs 3 and 4 above.
33. As of yet we can suggest no obvious kinetic advantage for the rearrangement to occur via the lithioalkynyl ether. A number of anion-accelerated [3,3]-sigmatropic rearrangements are known and take place at temperatures below their neutral counterparts: (a) Paquette, L. A. Tetrahedron 1997, 53, 13971.
34. (b) Paquette, L. A. Angew. Chem., Int. Ed. Engl. 1990, 29, 609.
35. (c) Hill, R. K. In Comprehensive Organic Synthesis; Trost, B. M., Fleming, I., Eds.; Pergamon Press: Oxford, 1991; Vol. 5, Chapter 7.1.
36. (d) Wilson, S. R. Org. React. 1993, 43, 93.