A highly active palladium catalyst system for the arylation of anilines

Tetrahedron Letters

Volumn 39, Issue 30, 1998, Pages 5327-5330

  Sadighi, Joseph P ^a   Harris, Michele C ^a   Buchwald, Stephen L ^a  

^a MASSACHUSETTS INSTITUTE OF TECHNOLOGY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ANILINE DERIVATIVE; BROMINE; PALLADIUM;

ARTICLE; CATALYSIS; CATALYST; CHELATION; LIGAND BINDING; SYNTHESIS; X RAY CRYSTALLOGRAPHY;

EID: 0032560779     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(98)00988-5     Document Type: Article

References (20)

1. (1) (a) Wolfe, J. P.; Wagaw, S.; Buchwald, S. L. J. Am. Chem. Soc. 1996, 118, 7215-7216.
2. (b) Driver, M. S.; Hartwig, J. F. J. Am. Chem. Soc. 1996, 118, 7217-7218.
3. (c) Wolfe, J. P.; Buchwald, S. L. Tetrahedron Lett. 1997, 38, 6359-6362.
4. (d) Wolfe, J. P.; Buchwald, S. L. J. Am. Chem. Soc. 1997, 119, 6054-6058.
5. (e) Wolfe, J. P.; Buchwald, S. L. J. Org. Chem. 1997, 62, 6066-6068.
6. (f) Wolfe, J. P.; Buchwald, S. L. J. Org. Chem. 1997, 62, 1264-1267.
7. (g) Louie, J.; Driver, M. S.; Hamann, B. C.; Hartwig, J. F. J. Org. Chem. 1997, 62, 1268-1273.
8. (h) Åhman, J.; Buchwald, S. L. Tetrahedron Lett. 1997, 38, 6363-6366.
9. (i) Wolfe, J. P.; Åhman, J.; Sadighi, J. P.; Singer, R. A.; Buchwald, S. L. Tetrahedron Lett. 1997, 63, 6367-6370.
10. (j) Mann, G.; Hartwig, J. F.; Driver, M. S.; Fernández-Rivas, C. J. Am. Chem. Soc. 1998, 120, 827-828.
11. (k) Louie, J.; Hartwig, J. F.; Fry, A. J. J. Am. Chem. Soc. 1997, 119, 11695-11696.
12. (l) Thayumanavan, S.; Barlow, S.; Marder, S. R. Chem. Mater. 1997, 9, 3231-3235.
13. (2) Singer, R. A.; Sadighi, J. P.; Buchwald, S. L. J. Am. Chem. Soc. 1998, 120, 213-214.
14. (3) Kranenburg, M.; van der Burgt, Y. E. M.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Goubitz, K.; Fraanje, J. Organometallics 1995, 14, 3081-3089.
15. (4) Kranenburg, M.; Delis, J. G. P.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Vrieze, K.; Veldman, N.; Spek, A. L.; Goubitz, K.; Fraanje, J. J. Chem. Soc., Dalton Trans. 1997, 1839-1849.
16. (5) While this manuscript was in preparation, a mechanistic paper was published on the amination of aryl halides using bidentate phosphines, including DPEphos and certain analogues: Hamann, B. C.; Hartwig, J. F. J. Am. Chem. Soc. 1998, 120, 3694-3703.
17. (6) Representative Procedure: An oven-dried Schlenk tube was charged with p-toluidine (1.20 mmol), palladium acetate (0.005 mmol) and DPEphos (0.0075 mmol), evacuated, and repressurized with argon. 2-Bromoanisole was added to the flask via syringe, followed by toluene (2 mL). The resulting mixture was stirred for 5 min at room temperature, affording a clear yellow solution. The flask was opened and solid sodium (erf-butoxide (1.40 mmol) was added in one portion, causing the solution to turn a deep red color. The flask was purged for 3 min with argon, and the mixture was heated with stirring to 80 °C until the aryl bromide had been consumed as judged by GC analysis. The mixture was then cooled to room temperature, taken up in diethyl ether (40 mL), and washed with brine. The resulting solution was dried over anhydrous potassium carbonate, filtered, and concentrated. The crude product was purified by flash chromatography on silica gel using 9:1 hexanes:ethyl acetate as the eluant, affording the product as a pale yellow oil in 94% yield. Note that the order of addition described above, in which the base is added after the palladium acetate has been mixed with the ligand and the amine, has been found to be important in the activation of the catalyst: Wolfe, J. P.; Buchwald, S. L. Unpublished results.
18. (7) The coupling of p-toluidine with 4-bromo-tert-butylbenzene using 0.5 mol % Pd (reaction condition A; see Table) proceeds quantitatively, as judged by GC analysis, within 2.5 h. In the presence of the cyanodiarylamine product of entry 6 (1 equiv.), this reaction proceeds to ca. 30% conversion after 18 h. The use of a larger excess of base did not improve the conversion.
19. (8) Previously reported compounds: (a) 2,4′,5-trimethyldiphenylamine (entry 2) and 2-methoxy-4′-methyldiphenylamine (entry 3): Sundberg, R. J.; Sloan, K. B. J. Org. Chem. 1973, 38, 2052-2057.
20. (b) N-biphenyl-4-yl-N,N-diphenylamine (entry 7): Piccard, J.; de Montmollin, F. Helv. Chim. Acta 1923, 6, 1011-1019.