Highly regioselective catalytic oxidative coupling reactions: Synthetic and mechanistic investigations

Journal of the American Chemical Society

Volumn 128, Issue 43, 2006, Pages 14047-14049

  Hull, Kami L ^a   Lanni, Erica L ^a   Sanford, Melanie S ^a  

^a UNIVERSITY OF MICHIGAN   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CARBON; HYDROGEN; ORGANOMETALLIC COMPOUND; PALLADIUM;

ARTICLE; CATALYSIS; CHEMICAL BOND; CHEMICAL REACTION; CROSS COUPLING REACTION; ELIMINATION REACTION; METALLATION; OXIDATION; REACTION ANALYSIS; REDUCTION; REGIOSELECTIVITY; ROOM TEMPERATURE; STEREOCHEMISTRY; SYNTHESIS; TRANSMETALLATION;

BIOLOGICAL PRODUCTS; CATALYSIS; OXIDATION-REDUCTION;

EID: 33750438087     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja065718e     Document Type: Article

References (31)

1. Hassan, J.; Sevignon, M.; Gozzl, C.; Schulz, E.; Lemaire, M. Chem. Rev. 2002, 102, 1359 and references therein.
2. For recent examples of Pd-catalyzed C-H activation/C-C coupling, see: (a) Okazawa, T.; Satoh, T.; Miura, M.; Nomura, M. J. Am. Chem. Soc. 2002, 124, 5286 and references therein.
3. (b) Kalyani, D.; Deprez, N. R.; Desai, L. V.; Sanford, M. S. J. Am. Chem. Soc. 2005, 127, 7330.
4. (c) Daugulis, O.; Zaitsev, V. G. Angew. Chem., Int. Ed. 2005, 44, 4046.
5. (d) Campeau, L.-C.; Parisien, M.; Jean, A.; Fagnou, K. J. Am. Chem. Soc. 2006, 128, 581.
6. (e) Lafrance, M.; Rowley, C. N.; Woo, T. K.; Fagnou, K. J. Am. Chem. Soc. 2006, 128, 8754.
7. For arene oxidative coupling catalyzed by other metals, see: (a) Li, C.-J.; Li, Z. Pure Appl. Chem. 2006, 78, 935 and references therein.
8. (b) Matsushita, M.; Kamata, K.; Yamaguchi, K.; Mizuno, N. J. Am. Chem. Soc. 2005, 127, 6632.
9. (c) Li, X. L.; Hewgley, J. B.; Mulrooney, C. A.; Yang, J. M.; Kozlowski, M. C. J. Org. Chem. 2003, 68, 5500.
10. (a) Review: Shilov, A. E.; Shul'pin, G. B. Chem. Rev. 1997, 97, 2879.
11. (b) van Helden, R.; Verberg, G. Recl. Trav. Chim. Pays-Bas 1965, 84, 1263.
12. (c) Burton, H. A.; Kozhevnikov, I. V. J. Mol. Catal., A 2002, 185, 285.
13. (d) Yokota, T.; Sakaguchi, S.; Ishii, Y. Adv. Synth. Catal. 2002, 344, 849.
14. (e) Ackerman, L. J.; Sadighi, J. P.; Kurtz, D. M.; Labinger, J. A.; Bercaw. J. E. Organometallics 2003, 22, 3884.
15. Pd-catalyzed oxidative coupling of thiophenes: Takahashi, M.; Masui, K.; Sekiguchi, H.; Kobayashi, N.; Mori, A.; Funahashi, M.; Tamaoki, N. J. Am. Chem. Soc. 2006, 128, 10930 and references therein.
16. II/0 -catalyzed oxidative coupling of methyl benzoate has been shown to proceed with reasonable (72%) selectivity for the 2.2′-isomer; however, this transformation proceeds with low (∼15%) conversion. The selectivity is proposed to result from coordination of the ester moiety to Pd. Lee, S. H.; Lee, K. H.; Lee, J. S.; Jung, J. D.; Shim, J. S. J. Mol. Catal., A 1997, 115, 241.
17. For example, see: (a) Dick, A. R.; Hull, K. L.; Sanford, M. S. J. Am. Chem. Soc. 2004, 126, 2300.
18. (b) Desai, L. V.; Hull, K. L.; Sanford, M. S. J. Am. Chem. Soc. 2004, 126, 9542.
19. (c) Kalyani, D.; Sanford, M. S. Org. Lett. 2005, 7, 4149.
20. (d) Giri, R.; Liang, J.; Lei, J. G.; Li, J. J.; Wang, D. H.; Chen, X.; Naggar, I. C.; Guo, C. Y.; Foxman, B. M.; Yu, J. Q. Angew. Chem., Int. Ed. 2005, 44, 7420.
21. (e) Desai, L. V.; Malik, H. A.; Sanford, M. S. Org. Lett. 2006, 8, 1141.
22. In i-PrOH and MeOH, significant amounts of ortho-ether products were formed as the reaction temperature was increased (see refs 7a,e).
23. Constable, E. C.; Sousa, L. R. J. Organomet. Chem. 1992, 427, 125.
24. Less than 5% of a third possible isomer (resulting from symmetrical coupling at the more hindered ortho-position) was observed.
25. IV complexes similar to D can be stable at room temperature. However, the reactivity of these compounds is highly dependent on the nature of the anionic ligands (L in complex D) and solvent. As such, we believe that derivatives of D are plausible intermediates in the current reactions. Dick, A. R.; Kampf, J. W.; Sanford, M. S. J. Am. Chem. Soc. 2005, 127, 12790.
26. We have also examined the direct reaction of B with Oxone (a key step of mechanism III) and found that it cleanly affords oxidative coupling product 3. However, when this same experiment was conducted in the presence of 1 equiv of free 2-o-tolylpyridine, a mixture of 3 (42%), 10 (46%), and 1 (12%) was generated. The crossover product-heterodimer 10-would not be formed if B were oxidized directly and quantitatively by Oxone. Instead, it appears to be to be produced via competing protonation of B by the moderately acidic oxidant (see eq 6 for a related protonation reaction). (Notably, the pH of a 0.06 M aqueous solution of Oxone is 1.84.) After protonation of B to form A and 1 equiv of 2-phenyl-3-methylpyridine, the reaction would proceed by analogy to eq 4. As a result, this experiment does not provide definitive data to distinguish mechanisms III and IV. For a more detailed discussion of this experiment. see the Supporting Information.
27. For further evidence against the formation of B (and therefore against mechanism III), see: Ryabov, A. D. Inorg. Chem. 1987, 26, 1252.
28. Traces of equilibration products were observed when these reactions were conducted at significantly higher temperatures (∼100 °C) or when they were carried out in neat AcOH at 60 °C. For a discussion of the mechanism of equilibration under these conditions (which is not believed to involve intermediates analogous to B-1), see ret 13.
29. While we cannot rule out an intermediate with an alternative geometry than B/B-1. we believe that it should undergo analogous equilibration.
30. IV.
31. IV centers, see ref 4a.