Ortho- and para-substituted Hoveyda-Grubbs carbenes. An improved synthesis of highly efficient metathesis initiators

Journal of Organic Chemistry

Volumn 69, Issue 20, 2004, Pages 6894-6896

  Bujok, Robert ^a   Bieniek, Michal ^a   Masnyk, Marek ^a   Michrowska, Anna ^a   Sarosiek, Agata ^a,d   Stȩpowska, Halszka ^a   Arlt, Dieter ^b,c   Grela, Karol ^a  

^a INSTITUTE OF ORGANIC CHEMISTRY   (Poland)

^b Ligand Chemie GmbH   (Germany)

^c UNIVERSITY OF COLOGNE   (Germany)

^d INDUSTRIAL CHEMISTRY RESEARCH INSTITUTE   (Poland)

Author keywords

[No Author keywords available]

Indexed keywords

CATALYSTS; STYRENE; SUBSTITUTION REACTIONS;

HOVEYDA-GRUBBS CARBENES; HOVEYDA-GRUBBS CATALYSTS;

OLEFINS;

2 ISOPROPOXY 3 PHENYLSTYRENE; 5 NITRO 2 ISOPROPOXYSTYRENE; CARBENOID; RUTHENIUM COMPLEX; STYRENE DERIVATIVE; UNCLASSIFIED DRUG;

ARTICLE; CHEMICAL STRUCTURE; COMPLEX FORMATION; RING CLOSING METATHESIS; SUBSTITUTION REACTION; SYNTHESIS;

EID: 4644298316     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo049222w     Document Type: Article

References (59)

1. Pertinent reviews: (a) Schrock, R. R.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2003, 42, 4592-4633. (b) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18-29. (c) Forstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012-3043. (d) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413-4450. (e) Schuster, M.; Blechert, S. Angew. Chem., Int. Ed. Engl. 1997, 36, 2037-2056. (f) Dragutan, V.; Dragutan, I.; Balaban, A. T. Platinum Met. Rev. 2001, 45, 155-163.
2. Pertinent reviews: (a) Schrock, R. R.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2003, 42, 4592-4633. (b) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18-29. (c) Forstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012-3043. (d) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413-4450. (e) Schuster, M.; Blechert, S. Angew. Chem., Int. Ed. Engl. 1997, 36, 2037-2056. (f) Dragutan, V.; Dragutan, I.; Balaban, A. T. Platinum Met. Rev. 2001, 45, 155-163.
3. Pertinent reviews: (a) Schrock, R. R.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2003, 42, 4592-4633. (b) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18-29. (c) Forstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012-3043. (d) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413-4450. (e) Schuster, M.; Blechert, S. Angew. Chem., Int. Ed. Engl. 1997, 36, 2037-2056. (f) Dragutan, V.; Dragutan, I.; Balaban, A. T. Platinum Met. Rev. 2001, 45, 155-163.
4. Pertinent reviews: (a) Schrock, R. R.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2003, 42, 4592-4633. (b) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18-29. (c) Forstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012-3043. (d) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413-4450. (e) Schuster, M.; Blechert, S. Angew. Chem., Int. Ed. Engl. 1997, 36, 2037-2056. (f) Dragutan, V.; Dragutan, I.; Balaban, A. T. Platinum Met. Rev. 2001, 45, 155-163.
5. Pertinent reviews: (a) Schrock, R. R.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2003, 42, 4592-4633. (b) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18-29. (c) Forstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012-3043. (d) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413-4450. (e) Schuster, M.; Blechert, S. Angew. Chem., Int. Ed. Engl. 1997, 36, 2037-2056. (f) Dragutan, V.; Dragutan, I.; Balaban, A. T. Platinum Met. Rev. 2001, 45, 155-163.
6. Pertinent reviews: (a) Schrock, R. R.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2003, 42, 4592-4633. (b) Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18-29. (c) Forstner, A. Angew. Chem., Int. Ed. 2000, 39, 3012-3043. (d) Grubbs, R. H.; Chang, S. Tetrahedron 1998, 54, 4413-4450. (e) Schuster, M.; Blechert, S. Angew. Chem., Int. Ed. Engl. 1997, 36, 2037-2056. (f) Dragutan, V.; Dragutan, I.; Balaban, A. T. Platinum Met. Rev. 2001, 45, 155-163.
7. (a) Kingsbury, J. S.; Harrity, J. P. A.; Bonitatebus, P. J.; Hoveyda, A. H. J. Am. Chem. Soc. 1999, 121, 791-799.
8. (b) Garber, S. B.; Kingsbury, J. S.; Gray, B. L.; Hoveyda, A. H. J. Am. Chem. Soc. 2000, 122, 8168-8179.
9. (c) For a short review on these catalysts, see: Hoveyda, A. H.; Gillingham, D. G.; Van Veldhuizen, J. J.; Kataoka, O.; Garber, S. B.; Kingsbury, J. S.; Harrity, J. P. A. Org. Biomol. Chem. 2004, 2, 1-16.
10. For syntheses of supported variants of 2, see inter alia: ref 2b and (a) Kingsbury, J. S.; Garber, S. B.; Giftos, J. M.; Gray, B. L.; Okamoto, M. M.; Farrer, R. A.; Fourkas, J. T.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2001, 40, 4251-4255. (b) Grela, K.; Tryznowski, M.; Bieniek, M. Tetrahedron Lett. 2002, 43, 9055-9059. (c) Connon, S. J.; Dunne, A. M.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 3835-3838. (d) Dowden, J.; Savovic, J. Chem. Commun. 2001, 37-38. (e) Yao, Q. Angew. Chem., Int. Ed. 2000, 39, 3896-3898. (f) Yao, Q.; Zhang, Y. Angew. Chem., Int. Ed. 2003, 42, 3395-3398. (g) Connon, S. J.; Blechert, S. Bioorg. Med. Chem. Lett. 2002, 12, 1873-1876. (h) Yao, Q.; Zhang, Y. J. Am. Chem. Soc. 2004, 12, 74-75. (i) Yao, Q.; Motta, A. R. Tetrahedron Lett. 2004, 45, 2447-2451.
11. For syntheses of supported variants of 2, see inter alia: ref 2b and (a) Kingsbury, J. S.; Garber, S. B.; Giftos, J. M.; Gray, B. L.; Okamoto, M. M.; Farrer, R. A.; Fourkas, J. T.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2001, 40, 4251-4255. (b) Grela, K.; Tryznowski, M.; Bieniek, M. Tetrahedron Lett. 2002, 43, 9055-9059. (c) Connon, S. J.; Dunne, A. M.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 3835-3838. (d) Dowden, J.; Savovic, J. Chem. Commun. 2001, 37-38. (e) Yao, Q. Angew. Chem., Int. Ed. 2000, 39, 3896-3898. (f) Yao, Q.; Zhang, Y. Angew. Chem., Int. Ed. 2003, 42, 3395-3398. (g) Connon, S. J.; Blechert, S. Bioorg. Med. Chem. Lett. 2002, 12, 1873-1876. (h) Yao, Q.; Zhang, Y. J. Am. Chem. Soc. 2004, 12, 74-75. (i) Yao, Q.; Motta, A. R. Tetrahedron Lett. 2004, 45, 2447-2451.
12. For syntheses of supported variants of 2, see inter alia: ref 2b and (a) Kingsbury, J. S.; Garber, S. B.; Giftos, J. M.; Gray, B. L.; Okamoto, M. M.; Farrer, R. A.; Fourkas, J. T.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2001, 40, 4251-4255. (b) Grela, K.; Tryznowski, M.; Bieniek, M. Tetrahedron Lett. 2002, 43, 9055-9059. (c) Connon, S. J.; Dunne, A. M.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 3835-3838. (d) Dowden, J.; Savovic, J. Chem. Commun. 2001, 37-38. (e) Yao, Q. Angew. Chem., Int. Ed. 2000, 39, 3896-3898. (f) Yao, Q.; Zhang, Y. Angew. Chem., Int. Ed. 2003, 42, 3395-3398. (g) Connon, S. J.; Blechert, S. Bioorg. Med. Chem. Lett. 2002, 12, 1873-1876. (h) Yao, Q.; Zhang, Y. J. Am. Chem. Soc. 2004, 12, 74-75. (i) Yao, Q.; Motta, A. R. Tetrahedron Lett. 2004, 45, 2447-2451.
13. For syntheses of supported variants of 2, see inter alia: ref 2b and (a) Kingsbury, J. S.; Garber, S. B.; Giftos, J. M.; Gray, B. L.; Okamoto, M. M.; Farrer, R. A.; Fourkas, J. T.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2001, 40, 4251-4255. (b) Grela, K.; Tryznowski, M.; Bieniek, M. Tetrahedron Lett. 2002, 43, 9055-9059. (c) Connon, S. J.; Dunne, A. M.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 3835-3838. (d) Dowden, J.; Savovic, J. Chem. Commun. 2001, 37-38. (e) Yao, Q. Angew. Chem., Int. Ed. 2000, 39, 3896-3898. (f) Yao, Q.; Zhang, Y. Angew. Chem., Int. Ed. 2003, 42, 3395-3398. (g) Connon, S. J.; Blechert, S. Bioorg. Med. Chem. Lett. 2002, 12, 1873-1876. (h) Yao, Q.; Zhang, Y. J. Am. Chem. Soc. 2004, 12, 74-75. (i) Yao, Q.; Motta, A. R. Tetrahedron Lett. 2004, 45, 2447-2451.
14. For syntheses of supported variants of 2, see inter alia: ref 2b and (a) Kingsbury, J. S.; Garber, S. B.; Giftos, J. M.; Gray, B. L.; Okamoto, M. M.; Farrer, R. A.; Fourkas, J. T.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2001, 40, 4251-4255. (b) Grela, K.; Tryznowski, M.; Bieniek, M. Tetrahedron Lett. 2002, 43, 9055-9059. (c) Connon, S. J.; Dunne, A. M.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 3835-3838. (d) Dowden, J.; Savovic, J. Chem. Commun. 2001, 37-38. (e) Yao, Q. Angew. Chem., Int. Ed. 2000, 39, 3896-3898. (f) Yao, Q.; Zhang, Y. Angew. Chem., Int. Ed. 2003, 42, 3395-3398. (g) Connon, S. J.; Blechert, S. Bioorg. Med. Chem. Lett. 2002, 12, 1873-1876. (h) Yao, Q.; Zhang, Y. J. Am. Chem. Soc. 2004, 12, 74-75. (i) Yao, Q.; Motta, A. R. Tetrahedron Lett. 2004, 45, 2447-2451.
15. For syntheses of supported variants of 2, see inter alia: ref 2b and (a) Kingsbury, J. S.; Garber, S. B.; Giftos, J. M.; Gray, B. L.; Okamoto, M. M.; Farrer, R. A.; Fourkas, J. T.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2001, 40, 4251-4255. (b) Grela, K.; Tryznowski, M.; Bieniek, M. Tetrahedron Lett. 2002, 43, 9055-9059. (c) Connon, S. J.; Dunne, A. M.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 3835-3838. (d) Dowden, J.; Savovic, J. Chem. Commun. 2001, 37-38. (e) Yao, Q. Angew. Chem., Int. Ed. 2000, 39, 3896-3898. (f) Yao, Q.; Zhang, Y. Angew. Chem., Int. Ed. 2003, 42, 3395-3398. (g) Connon, S. J.; Blechert, S. Bioorg. Med. Chem. Lett. 2002, 12, 1873-1876. (h) Yao, Q.; Zhang, Y. J. Am. Chem. Soc. 2004, 12, 74-75. (i) Yao, Q.; Motta, A. R. Tetrahedron Lett. 2004, 45, 2447-2451.
16. For syntheses of supported variants of 2, see inter alia: ref 2b and (a) Kingsbury, J. S.; Garber, S. B.; Giftos, J. M.; Gray, B. L.; Okamoto, M. M.; Farrer, R. A.; Fourkas, J. T.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2001, 40, 4251-4255. (b) Grela, K.; Tryznowski, M.; Bieniek, M. Tetrahedron Lett. 2002, 43, 9055-9059. (c) Connon, S. J.; Dunne, A. M.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 3835-3838. (d) Dowden, J.; Savovic, J. Chem. Commun. 2001, 37-38. (e) Yao, Q. Angew. Chem., Int. Ed. 2000, 39, 3896-3898. (f) Yao, Q.; Zhang, Y. Angew. Chem., Int. Ed. 2003, 42, 3395-3398. (g) Connon, S. J.; Blechert, S. Bioorg. Med. Chem. Lett. 2002, 12, 1873-1876. (h) Yao, Q.; Zhang, Y. J. Am. Chem. Soc. 2004, 12, 74-75. (i) Yao, Q.; Motta, A. R. Tetrahedron Lett. 2004, 45, 2447-2451.
17. For syntheses of supported variants of 2, see inter alia: ref 2b and (a) Kingsbury, J. S.; Garber, S. B.; Giftos, J. M.; Gray, B. L.; Okamoto, M. M.; Farrer, R. A.; Fourkas, J. T.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2001, 40, 4251-4255. (b) Grela, K.; Tryznowski, M.; Bieniek, M. Tetrahedron Lett. 2002, 43, 9055-9059. (c) Connon, S. J.; Dunne, A. M.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 3835-3838. (d) Dowden, J.; Savovic, J. Chem. Commun. 2001, 37-38. (e) Yao, Q. Angew. Chem., Int. Ed. 2000, 39, 3896-3898. (f) Yao, Q.; Zhang, Y. Angew. Chem., Int. Ed. 2003, 42, 3395-3398. (g) Connon, S. J.; Blechert, S. Bioorg. Med. Chem. Lett. 2002, 12, 1873-1876. (h) Yao, Q.; Zhang, Y. J. Am. Chem. Soc. 2004, 12, 74-75. (i) Yao, Q.; Motta, A. R. Tetrahedron Lett. 2004, 45, 2447-2451.
18. For syntheses of supported variants of 2, see inter alia: ref 2b and (a) Kingsbury, J. S.; Garber, S. B.; Giftos, J. M.; Gray, B. L.; Okamoto, M. M.; Farrer, R. A.; Fourkas, J. T.; Hoveyda, A. H. Angew. Chem., Int. Ed. 2001, 40, 4251-4255. (b) Grela, K.; Tryznowski, M.; Bieniek, M. Tetrahedron Lett. 2002, 43, 9055-9059. (c) Connon, S. J.; Dunne, A. M.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 3835-3838. (d) Dowden, J.; Savovic, J. Chem. Commun. 2001, 37-38. (e) Yao, Q. Angew. Chem., Int. Ed. 2000, 39, 3896-3898. (f) Yao, Q.; Zhang, Y. Angew. Chem., Int. Ed. 2003, 42, 3395-3398. (g) Connon, S. J.; Blechert, S. Bioorg. Med. Chem. Lett. 2002, 12, 1873-1876. (h) Yao, Q.; Zhang, Y. J. Am. Chem. Soc. 2004, 12, 74-75. (i) Yao, Q.; Motta, A. R. Tetrahedron Lett. 2004, 45, 2447-2451.
19. Catalysts 1-3 are commercially available from Aldrich Chemical Co.
20. For a comparison of relative initiation rates of 2 and 3, see; refs 6, 8a,b, and 10.
21. (a) Grela, K.; Kim, M. Eur. J. Org. Chem. 2003, 963-966.
22. (b) For an unique activity of a catalyst derived from 4 in living polymerization of diynes, see: Krause, J. O.; Zarka, M. T.; Anders, U.; Weberskirch, R.; Nuyken, O.; Buchmeiser, M. R. Angew. Chem., Int. Ed. 2003, 42, 5965-5969.
23. (a) Randl, S.; Gessler, S.; Wakamatsu, H.; Blechert, S. Synlett 2001, 430-432.
24. For activation of Grubbs' carbene 2 towards acrylo nitrile, either via structural modifications or addition of CuCl, see: (b) Love, J. A.; Morgan, J. P.; Trnka, T. M.; Grubbs, R. H. Angew. Chem., Int. Ed. 2002, 41, 4035-4037. (c) Rivard, M.; Blechert, S. Eur. J. Org. Chem. 2003, 2225-2228. (d) Imhof, S.; Randl, S.; Blechert, S. Chem. Commun. 2001, 1692-1693. (e) Grela, K.; Michrowska, A.; Bieniek, M.; Kim, M.; Klajn, R. Tetrahedron 2003, 59, 4525-4531.
25. For activation of Grubbs' carbene 2 towards acrylo nitrile, either via structural modifications or addition of CuCl, see: (b) Love, J. A.; Morgan, J. P.; Trnka, T. M.; Grubbs, R. H. Angew. Chem., Int. Ed. 2002, 41, 4035-4037. (c) Rivard, M.; Blechert, S. Eur. J. Org. Chem. 2003, 2225-2228. (d) Imhof, S.; Randl, S.; Blechert, S. Chem. Commun. 2001, 1692-1693. (e) Grela, K.; Michrowska, A.; Bieniek, M.; Kim, M.; Klajn, R. Tetrahedron 2003, 59, 4525-4531.
26. For activation of Grubbs' carbene 2 towards acrylo nitrile, either via structural modifications or addition of CuCl, see: (b) Love, J. A.; Morgan, J. P.; Trnka, T. M.; Grubbs, R. H. Angew. Chem., Int. Ed. 2002, 41, 4035-4037. (c) Rivard, M.; Blechert, S. Eur. J. Org. Chem. 2003, 2225-2228. (d) Imhof, S.; Randl, S.; Blechert, S. Chem. Commun. 2001, 1692-1693. (e) Grela, K.; Michrowska, A.; Bieniek, M.; Kim, M.; Klajn, R. Tetrahedron 2003, 59, 4525-4531.
27. For activation of Grubbs' carbene 2 towards acrylo nitrile, either via structural modifications or addition of CuCl, see: (b) Love, J. A.; Morgan, J. P.; Trnka, T. M.; Grubbs, R. H. Angew. Chem., Int. Ed. 2002, 41, 4035-4037. (c) Rivard, M.; Blechert, S. Eur. J. Org. Chem. 2003, 2225-2228. (d) Imhof, S.; Randl, S.; Blechert, S. Chem. Commun. 2001, 1692-1693. (e) Grela, K.; Michrowska, A.; Bieniek, M.; Kim, M.; Klajn, R. Tetrahedron 2003, 59, 4525-4531.
28. (a) Wakamatsu, H.; Blechert, S. Angew. Chem., Int. Ed. 2002, 41, 2403-2405.
29. (b) For an improved synthesis of 5, see: Dunne, A. M.; Mix, S.; Blechert, S. Tetrahedron Lett. 2003, 44, 2733-2736.
30. Extensive studies described in ref 8 suggest that a steric bulk adjacent to the chelating isopropoxy moiety is the crucial factor securing the unusually high activity of 5.
31. (a) Grela, K.; Harutyunyan, S.; Michrowska, A. Angew. Chem., Int. Ed. 2002, 41, 4038-4040.
32. (b) Harutyunyan, S.; Michrowska, A.; Grela, K. A Highly Active Ruthenium (Pre)catalyst for Metathesis Reactions. In Catalysts for Fine Chemical Synthesis; Roberts, S., Ed.; Wiley-Interscience: New York, 2004; Vol. 3, in press.
33. For applications of 6 in target-oriented synthesis, see the following. (c) (-)-Securinine: Honda, T.; Namiki, H.; Kaneda, K.; Mizutani, H. Org. Lett. 2004, 6, 87-89. (d) (+)-Viroallosecurinine: Honda, T.; Namiki, H.; Watanabe, M.; Mizutani, H. Tetrahedron Lett. 2004, 45, 5211-5213. (e) An artificial photosynthesis model: Ostrowski, S.; Mikus, A. Mol. Diversity 2003, 6, 315-321.
34. For applications of 6 in target-oriented synthesis, see the following. (c) (-)-Securinine: Honda, T.; Namiki, H.; Kaneda, K.; Mizutani, H. Org. Lett. 2004, 6, 87-89. (d) (+)-Viroallosecurinine: Honda, T.; Namiki, H.; Watanabe, M.; Mizutani, H. Tetrahedron Lett. 2004, 45, 5211-5213. (e) An artificial photosynthesis model: Ostrowski, S.; Mikus, A. Mol. Diversity 2003, 6, 315-321.
35. For applications of 6 in target-oriented synthesis, see the following. (c) (-)-Securinine: Honda, T.; Namiki, H.; Kaneda, K.; Mizutani, H. Org. Lett. 2004, 6, 87-89. (d) (+)-Viroallosecurinine: Honda, T.; Namiki, H.; Watanabe, M.; Mizutani, H. Tetrahedron Lett. 2004, 45, 5211-5213. (e) An artificial photosynthesis model: Ostrowski, S.; Mikus, A. Mol. Diversity 2003, 6, 315-321.
36. (a) For a recent application of Ru catalysts derived from 5-nitro-2-isopropoxystyrene in polymer chemistry, see: Krause, J. O.; Nuyken, O.; Buchmeiser, M. R. Chem. Eur. J. 2004, 10, 2029-2035.
37. (b) Recently, the concept of steric and electronic activation has been utilized by Hoveyda et al. in a preparation of chiral ruthenium complexes for asymmetric metathesis: Van Veldhuizen, J. J.; Gillingham, D. G.; Garber, S. B.; Kataoka, O.; Hoveyda, A. H. J. Am. Chem. Soc. 2003, 125, 12502-12508.
38. See Supporting Information for experimental details.
39. (a) For a review on Claisen rearrangement, see: Rhoadas, S. J.; Raulis, N. R. Org. React. 1975, 22, 1-252.
40. For a similar Claisen rearrangement-isomerization protocol of phenol allyl ethers applied in total syntheses, see: (b) Baxendale, I. R.; Lee, A.-L.; Ley, S. V. J. Chem. Soc., Perkin Trans. 1 2002, 1850-1857. (c) Nguyen Van, T.; Debenedetti, S.; De Kimpe, N. Tetrahedron Lett. 2003, 44, 4199-4201. (d) De Koning, C. B.; Green, I. R.; Michael, J. P.; Oliveira, J. R. Tetrahedron 2001, 57, 9623-9634.
41. For a similar Claisen rearrangement-isomerization protocol of phenol allyl ethers applied in total syntheses, see: (b) Baxendale, I. R.; Lee, A.-L.; Ley, S. V. J. Chem. Soc., Perkin Trans. 1 2002, 1850-1857. (c) Nguyen Van, T.; Debenedetti, S.; De Kimpe, N. Tetrahedron Lett. 2003, 44, 4199-4201. (d) De Koning, C. B.; Green, I. R.; Michael, J. P.; Oliveira, J. R. Tetrahedron 2001, 57, 9623-9634.
42. For a similar Claisen rearrangement-isomerization protocol of phenol allyl ethers applied in total syntheses, see: (b) Baxendale, I. R.; Lee, A.-L.; Ley, S. V. J. Chem. Soc., Perkin Trans. 1 2002, 1850-1857. (c) Nguyen Van, T.; Debenedetti, S.; De Kimpe, N. Tetrahedron Lett. 2003, 44, 4199-4201. (d) De Koning, C. B.; Green, I. R.; Michael, J. P.; Oliveira, J. R. Tetrahedron 2001, 57, 9623-9634.
43. 3 isomerization of structurally related 2-isopropoxyallylbenzenes, see: van Otterlo, W. A. L.; Pathak, R.; de Koning, C. B. Synlett 2003, 1859-1861.
44. 3 isomerization of structurally related 2-isopropoxyallylbenzenes, see: van Otterlo, W. A. L.; Pathak, R.; de Koning, C. B. Synlett 2003, 1859-1861.
45. 3 isomerization of structurally related 2-isopropoxyallylbenzenes, see: van Otterlo, W. A. L.; Pathak, R.; de Koning, C. B. Synlett 2003, 1859-1861.
46. 3 isomerization of structurally related 2-isopropoxyallylbenzenes, see: van Otterlo, W. A. L.; Pathak, R.; de Koning, C. B. Synlett 2003, 1859-1861.
47. 3 isomerization of structurally related 2-isopropoxyallylbenzenes, see: van Otterlo, W. A. L.; Pathak, R.; de Koning, C. B. Synlett 2003, 1859-1861.
48. 3 isomerization of structurally related 2-isopropoxyallylbenzenes, see: van Otterlo, W. A. L.; Pathak, R.; de Koning, C. B. Synlett 2003, 1859-1861.
49. 3 isomerization of structurally related 2-isopropoxyallylbenzenes, see: van Otterlo, W. A. L.; Pathak, R.; de Koning, C. B. Synlett 2003, 1859-1861.
50. In addition to the expected 11a (96% of yield) a small amount of the byproduct 11a′ (4% of yield) has been obtained.
51. 2-bearing 9b was carried out in a 1:1 w/w mixture with diphenyl ether, which can be then separated by a simple biphasic extraction and recycled.
52. Claisen rearrangement of this substrate is known to give moderate yields: White, W., N.; Gwyn, D.; Schlitt, R.; Girard, C.; Fife, W. J. Am. Chem. Soc. 1958, 80, 3271-3277 (o-dichloro benzene, 6 h, 59%).
53. The bromo-substituted styrene 12c constitutes a valuable starting material for preparation of a PS-DES-supported catalyst 7b; cf. ref 3b.
54. Arisawa, M.; Terada, Y.; Nakagawa, M.; Nishida, A. Angew. Chem., Int. Ed. 2002, 41, 4732-4734. (b)
55. (a) For a recent example of ruthenium isomerization catalyst formed in situ from 1, 2-propanol, and NaOH, see: Schmidt, B. Chem. Commun. 2004, 742-743.
56. For reviews on olefin isomerization caused by ruthenium metathesis catalysts, see: (b) Schmidt, B. Eur. J. Org. Chem. 2004, 1865-1880. (c) Alcaide, B.; Almendros, P. Chem. Eur. J. 2003, 9, 1259-1262.
57. For reviews on olefin isomerization caused by ruthenium metathesis catalysts, see: (b) Schmidt, B. Eur. J. Org. Chem. 2004, 1865-1880. (c) Alcaide, B.; Almendros, P. Chem. Eur. J. 2003, 9, 1259-1262.
58. (a) Recently, another example of an o-substituted Hoveyda-type catalyst has been described: Zaja, M.; Connon, S. J.; Dunne, A. M.; Rivard, M.; Buschmann, N.; Jiricek, J.; Blechert, S. Tetrahedron 2003, 59, 6545-6558.
59. (b) The high activity of this catalyst has been proved: Synlett 2004, 667-670.