Kinetically controlled cross-metathesis reactions with high E-olefin selectivities

Organic Letters

Volumn 3, Issue 14, 2001, Pages 2209-2212

  Engelhardt, F Conrad ^a   Schmitt, Michael J ^a   Taylor, Richard E ^a  

^a UNIVERSITY OF NOTRE DAME   (United States)

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ARTICLE;

EID: 0000338310     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol016061z     Document Type: Article

References (28)

1. For recent reviews of olefin metathesis, see: (a) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413. (b) Blackwell, H. E.; O'Leary, D. J.; Chatterjee, A. K.; Washenfelder, R. A.; Bussmann, D. A.; Grubbs, R. H. J. Am. Chem. Soc. 2000, 122, 58. Roy, R.; Das, S. K. Chem. Commun. 2000, 519. Grubbs, R. H.; Trnka, T. M. Acc. Chem. Res. 2001, 34, 18. (e) Fürstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012.
2. For recent reviews of olefin metathesis, see: (a) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413. (b) Blackwell, H. E.; O'Leary, D. J.; Chatterjee, A. K.; Washenfelder, R. A.; Bussmann, D. A.; Grubbs, R. H. J. Am. Chem. Soc. 2000, 122, 58. Roy, R.; Das, S. K. Chem. Commun. 2000, 519. Grubbs, R. H.; Trnka, T. M. Acc. Chem. Res. 2001, 34, 18. (e) Fürstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012.
3. For recent reviews of olefin metathesis, see: (a) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413. (b) Blackwell, H. E.; O'Leary, D. J.; Chatterjee, A. K.; Washenfelder, R. A.; Bussmann, D. A.; Grubbs, R. H. J. Am. Chem. Soc. 2000, 122, 58. Roy, R.; Das, S. K. Chem. Commun. 2000, 519. Grubbs, R. H.; Trnka, T. M. Acc. Chem. Res. 2001, 34, 18. (e) Fürstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012.
4. For recent reviews of olefin metathesis, see: (a) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413. (b) Blackwell, H. E.; O'Leary, D. J.; Chatterjee, A. K.; Washenfelder, R. A.; Bussmann, D. A.; Grubbs, R. H. J. Am. Chem. Soc. 2000, 122, 58. Roy, R.; Das, S. K. Chem. Commun. 2000, 519. Grubbs, R. H.; Trnka, T. M. Acc. Chem. Res. 2001, 34, 18. (e) Fürstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012.
5. For recent reviews of olefin metathesis, see: (a) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413. (b) Blackwell, H. E.; O'Leary, D. J.; Chatterjee, A. K.; Washenfelder, R. A.; Bussmann, D. A.; Grubbs, R. H. J. Am. Chem. Soc. 2000, 122, 58. Roy, R.; Das, S. K. Chem. Commun. 2000, 519. Grubbs, R. H.; Trnka, T. M. Acc. Chem. Res. 2001, 34, 18. (e) Fürstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012.
6. (a) Taylor, R. E.; Engelhardt, F. C.; Yuan, H. Org. Lett. 1999, 1, 1257. (b) Taylor, R. E.; Schmitt, M. J.; Yuan, H. Org. Lett. 2000, 2, 601.
7. (a) Taylor, R. E.; Engelhardt, F. C.; Yuan, H. Org. Lett. 1999, 1, 1257. (b) Taylor, R. E.; Schmitt, M. J.; Yuan, H. Org. Lett. 2000, 2, 601.
8. Unpublished results: The lack of reactivity of benzylidene catalyst 1 in the presence of a free hydroxyl in the homoallylic position is well-established. To circumvent the low reactivity problem in the CM reactions, we employed high catalyst concentrations (40-50 mol %) of 1. Though effective in facilitating the CM reaction (yields 20-40%), the highly colored metathesis products proved difficult to purify. Additionally, the highly colored products gave poor yields in later reactions due to lingering catalyst contaminants.
9. Scholl, M.; Ding, S.; Lee, C. W.; Grubbs, R. H. Org. Lett. 1999, 1, 953.
10. Taylor, R. E.; Engelhardt, F. C.; Schmitt, M. J.; Yuan, H. Q. J. Am. Chem. Soc. 2001, 123, 2964.
11. For comparable (E:Z) ratios in similar cross-metathesis reactions, see ref 1 and the following: (a) Chatterjee, A. K.; Grubbs, R. H. Org. Lett. 1999, 1, 1751. (b) Crowe, W. E.; Goldberg, D. R.; Zhang, Z. J. Tetrahedron Lett. 1996, 37, 2117.
12. For comparable (E:Z) ratios in similar cross-metathesis reactions, see ref 1 and the following: (a) Chatterjee, A. K.; Grubbs, R. H. Org. Lett. 1999, 1, 1751. (b) Crowe, W. E.; Goldberg, D. R.; Zhang, Z. J. Tetrahedron Lett. 1996, 37, 2117.
13. (a) Fürstner, A.; Thiel, O. R.; Ackermann, L. Org. Lett. 2001, 3, 449. (b) Smith, A. B., III; Adams, C. M.; Kozmin, S. A. J. Am. Chem. Soc. 2001, 123, 990.
14. (a) Fürstner, A.; Thiel, O. R.; Ackermann, L. Org. Lett. 2001, 3, 449. (b) Smith, A. B., III; Adams, C. M.; Kozmin, S. A. J. Am. Chem. Soc. 2001, 123, 990.
15. The CM reactions in Table 1 were run at varying concentrations (0.1-0.01 M) and reaction times (1-24 h) for several substrates. Despite the variant of conditions used, the observed E:Z ratio for the CM products was always the same for the respective substrate.
16. (a) Grubbs, R. H.; Dias, E. L.; Nguyen, SB. T. J. Am. Chem. Soc. 1997, 119, 3887. (b) Schaaf, P. A. V. D.; Kolly, R.; Hafner, A. Chem. Commun. 2000, 1045.
17. (a) Grubbs, R. H.; Dias, E. L.; Nguyen, SB. T. J. Am. Chem. Soc. 1997, 119, 3887. (b) Schaaf, P. A. V. D.; Kolly, R.; Hafner, A. Chem. Commun. 2000, 1045.
18. (a) Fürstner, A.; Langemann, K. J. Am. Chem. Soc. 1997, 119, 9130. (b) Ghosh, A. K.; Cappiello, J.; Shin, D. Tetrahedron Lett. 1998, 39, 4651. Roy, R.; Das, S. K. Chem. Commun. 2000, 519.
19. (a) Fürstner, A.; Langemann, K. J. Am. Chem. Soc. 1997, 119, 9130. (b) Ghosh, A. K.; Cappiello, J.; Shin, D. Tetrahedron Lett. 1998, 39, 4651. Roy, R.; Das, S. K. Chem. Commun. 2000, 519.
20. (a) Fürstner, A.; Langemann, K. J. Am. Chem. Soc. 1997, 119, 9130. (b) Ghosh, A. K.; Cappiello, J.; Shin, D. Tetrahedron Lett. 1998, 39, 4651. Roy, R.; Das, S. K. Chem. Commun. 2000, 519.
21. This sequestering effect sufficiently explains our difficulty in using catalyst 1 in the CM reaction of unprotected homoallylic alcohols with allyltrimethylsilane (ref 3).
22. (a) Hoveyda, A. H.; Bonitatebus, P. J., Jr.; Harrity, J. P. A.; Kingsbury, J. S. J. Am. Chem. Soc. 1999, 121, 791. (b) Hoveyda, A. H.; Gray, B. L.; Kingsbury, J. S.; Garber, S. B. J. Am. Chem. Soc. 2000, 122, 8168.
23. (a) Hoveyda, A. H.; Bonitatebus, P. J., Jr.; Harrity, J. P. A.; Kingsbury, J. S. J. Am. Chem. Soc. 1999, 121, 791. (b) Hoveyda, A. H.; Gray, B. L.; Kingsbury, J. S.; Garber, S. B. J. Am. Chem. Soc. 2000, 122, 8168.
24. Choi, T.-L.; Chatterjee, A. K.; Grubbs, R. H. Angew. Chem., Int. Ed. 2001, 40, 1277.
25. 1H: δ 7.26 ppm). The carbene proton in the parent benzylidene catalyst 2 appears 19.14 ppm, while the propagating methylidene appears at 17.78 ppm. The upfield shift of the carbene proton in structure 15/16 is highly suggestive of a chelate and matches well with Hoveyda's results of similar oxygen-ruthenium chelated structures (ref 12a).
26. 2Ph) and trimethylsilane, providing a similar argument for the enhanced E-olefin selectivity.
27. The low conversions of the silyl ethers to their corresponding CM products suggest a more sterically encumbered environment. This limitation can be overcome by recharging the reaction flask with more allyltrimethylsilane (4 equiv) and fresh catalyst 2 (5 mol %). Ultimately conversions of >80% for the CM product 22 were achievable. The E:Z ratios were independent of the percent conversion to the CM product.
28. 1H NMR. The higher E:Z ratios observed for 20 and 22 indicate the additional steric bulk incorporated into the molecules by the large TMS protecting group.