Convenient synthesis and transformation of 2,6-dichloro-4-iodopyridine

Organic Letters

Volumn 3, Issue 26, 2001, Pages 4263-4265

  Mello, Jesse V ^a   Finney, Nathaniel S ^a  

^a UNIVERSITY OF CALIFORNIA   (United States)

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ARTICLE;

EID: 0000658301     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol0169269     Document Type: Article

References (30)

1. Mello, J. V.; Finney, N. S. Angew. Chem., Int. Ed. 2001, 40, 1536.
2. For authoriative treatment of pyridine synthesis, see: (a) Katritzky, A. R. Handbook of Heterocyclic Chemistry, 2nd ed.; Pergammon: New York, 2000.
3. (b) Comprehensive Heterocyclic Chemistry; Katritzky, A. R., Rees, C. W., Eds; Pergammon: New York, 1984; Vol. 2.
4. For recent examples of the condensation of chalcones with acetophenone derivatives to form 2,4,6-triarylpyridines, see: (a) Chiu, C.; Tang, Z.; Ellingboe, J. J. Comb. Chem. 1999, 1, 73-77.
5. (b) Katritzky, A. R.; Abdel-Fattah, A. A. A.; Tymoshenko, D. O.; Essawy, S. A. Synthesis 1999, 2114-2118.
6. For representative overviews, see: (a) Biradha, K.; Fujita, M. Adv. Supramol. Chem. 2000, 6, 1.
7. (b) Long, N. J. In Optoelectronic Properties of Inorganic Compounds; Roundhill, D. M., Fackler, J. P., Jr., Eds.; Plenum: New York, 1999; pp 107-167. Publisher: Plenum Publishing Corp., New York.
8. (c) Krasovitskii, B. M.; Bolotin, B. M. Organic Luminescent Materials; VCH: New York, 1988.
9. The preparation of 4 from 2,6-dichloro-4-aminopyridine has been previously described. We have found the reported procedures for the synthesis and transformation of this key intermediate difficult to reduce to practice and have thus devised the approach presented here. See: Talik, T.; Plazek, E. Rocz. Chem. 1959, 33, 387, and references therein.
10. Complete experimental and spectroscopic details are provided in the Supporting Information.
11. Henegar, K. E.; Ashford, S. A.; Baughman, T. A.; Sih, J. C.; Gu, R.-L. J. Org. Chem. 1997, 62, 6588.
12. Pfister, J. R.; Wymann, W. E. Synthesis 1983, 38.
13. It is necessary to stir 3 in cold hydrochloric acid for several hours prior to diazotization in order to obtain an acceptable yield. See Supporting Information for details.
14. For a recent review, see: (a) Sonogashira, K. In Metal-Catalyzed Cross Coupling Reactions; Diederich, F., Stang, P. J., Eds.; Wiley-VCH: New York, 1998; Chapter 5.
15. (b) Negishi, E.-i. In Metal-Catalyzed Cross Coupling Reactions; Diederich, F., Stang, P. J., Eds.; Wiley-VCH: New York, 1998; Chapter 1.
16. For recent examples of the chemoselective cross-coupling of chloroiodo-and bromoiodopyridines, see: (a) Baxter, P. N. W. J. Org. Chem. 2000, 65, 1257-1272.
17. (b) Loren, J. C.; Siegel, J. S. Angew. Chem., Int. Ed 2001, 40, 754-757.
18. For representative earlier examples of the cross-coupling of halopyridines, see: (c) Zhang, H.; Chan, K. S. Tetrahedron Lett. 1996, 37, 1043-1044.
19. (d) Lohse, O.; Thevenin, P.; Waldvogel, E. Synlett 1999, 45-48.
20. 3 consistently provided the best yields of dicoupled products. See: (a) Old, D. W.; Wolfe, J. P.; Buchwald, S. L. J. Am. Chem. Soc. 1998, 120, 9722-9723.
21. (b) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. Engl. 1997, 37, 33387-3388.
22. (c) Wolfe, J. P.; Buchwald, S. L. Angew. Chem., Int. Ed. 1999, 38, 2413-2416.
23. (d) Littke, A. F.; Dai, C.; Fu, G. C. J. Am. Chem. Soc. 2000, 122, 4020-4028.
24. For reviews, see: (a) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457-2483.
25. (b) Suzuki, A. J. Organomet. Chem. 1999, 576, 147.
26. The reactions proceed cleanly, with residual starting material and decoupled products as the other major components of the reaction mixture.
27. NAr monosubstitution of dihalopyridines, see ref 7 and the following: (a) Testaferri, L.; Tiecco, M.; Tingoli, M.; Bartoli, D.; Massoli, A. Tetrahedron 1985, 41, 1373-1384.
28. (b) Murata, N.; Sugihara, T.; Kondo, Y.; Sakamoto. Synlett 1997, 298-300.
29. Pd-catalyzed amination of certain pyridyl triflates has been shown to require a chelating bisphosphine ligand: Arterburn, J. B.; Rao, K. V.; Ramdas, R.; Dible, B. R. Org. Lett. 2001, 3, 1351-1354.
30. The pyridone formed upon dechlorination and debenzylation of 20 is prone to over-reduction, although this problem is not observed in the hydrogenolysis of 21.