Alternative biarylphosphines for use in the palladium-catalyzed amination of aryl halides

Synthesis

Volumn , Issue 11, 2003, Pages 1727-1731

  Singer, Robert A ^a   Caron, Stephane ^a   McDermott, Ruth E ^a   Arpin, Patrice ^a   Do, Nga M ^a  

^a PFIZER INC   (United States)

Author keywords

Aminations; Biaryls; Catalysis; Ligands; Palladium

Indexed keywords

AMINATION; CATALYSIS; HALOGEN COMPOUNDS; NITROGEN COMPOUNDS; PALLADIUM; SUBSTRATES;

LIGANDS;

PHOSPHORUS COMPOUNDS;

HALIDE; PALLADIUM; PHOSPHINE DERIVATIVE; PYRAZOLE DERIVATIVE; PYRROLE DERIVATIVE;

AMINATION; ARTICLE; CATALYSIS; CHEMICAL STRUCTURE; CRYSTALLIZATION; POLYMERIZATION; REACTION ANALYSIS;

EID: 0042739198     PISSN: 00397881     EISSN: None     Source Type: Journal    
DOI: 10.1055/s-2003-40881     Document Type: Article

References (12)

1. For reviews on the Pd-catalyzed amination reaction, see: (a) Yang, B. H. ; Buchwald, S. L. J. Organomet. Chem. 1999, 576, 125. (b) Wolfe, J. P.; Wagaw, S.; Marcoux, J.-F.; Buchwald, S. L. Acc. Chem. Res. 1998, 31, 805. (c) Hartwig, J. F. Angew. Chem., Int. Ed. 1998, 37, 2046.
2. For reviews on the Pd-catalyzed amination reaction, see: (a) Yang, B. H. ; Buchwald, S. L. J. Organomet. Chem. 1999, 576, 125. (b) Wolfe, J. P.; Wagaw, S.; Marcoux, J.-F.; Buchwald, S. L. Acc. Chem. Res. 1998, 31, 805. (c) Hartwig, J. F. Angew. Chem., Int. Ed. 1998, 37, 2046.
3. For reviews on the Pd-catalyzed amination reaction, see: (a) Yang, B. H. ; Buchwald, S. L. J. Organomet. Chem. 1999, 576, 125. (b) Wolfe, J. P.; Wagaw, S.; Marcoux, J.-F.; Buchwald, S. L. Acc. Chem. Res. 1998, 31, 805. (c) Hartwig, J. F. Angew. Chem., Int. Ed. 1998, 37, 2046.
4. Lednicer, D. Strategies for Organic Drug Synthesis and Design; Wiley: New York, 1998.
5. (a) Wolfe, J. P.; Tomori, H.; Sadighi, J. P.; Yin, J.; Buchwald, S. L. J. Org. Chem. 2000, 65, 1158.
6. (b) Old, D. W.; Wolfe, J. P.; Buchwald, S. L. J. Am. Chem. Soc. 1998, 120, 9722.
7. For the typical preparation of the Buchwald group's biaryl ligands via a metal-catalyzed cross-coupling or via addition of an arylmagnesium halide to benzyne, followed by addition of a chlorodialkylphosphine, see: Tomori, H.; Fox, J. M.; Buchwald, S. L. J. Org. Chem. 2000, 65, 5334.
8. Various alkyllithiums were screened for the halogen-metal exchange, including s-BuLi and none provided significantly improved branching ratios. Organomagnesium derivatives were prepared as well but these had significantly poorer reactivity and required copper salts to obtain product. Ultimately, ligand 2 was used impure since the contaminants were not removed easily by recrystallization and were not considered impediments to the reaction.
9. Pyrazoles have been shown to ortho-directed deprotonation of an N-aryl group appended to the pyrazole; for an example, see: Micetich, R. G.; Baker, V. ; Spevak, P.; Hall, T. W.; Bains, B. K. Heterocycles 1985, 23, 943.
10. 3) turned yellow-green and resulted in poor reaction conversions. Adding t-BuONa led to restarting of the reactions and drove them to completion, suggesting t-BuONa can break aggregation of a Pd complex that is not competent in the catalytic cycle.
11. When carrying out the coupling of morpholine and 4-tert-butylphenylbromide in toluene with 1% Pd catalyst, the reaction only reached 22% conversion, while the same reaction in tert-amyl alcohol reached completion in under 2 h. Use of butan-2-ol accelerated the reaction further, but significant dehalogenation of the aryl bromide was observed (due to β-hydride elimination).
12. Balaban, A. T. Tetrahedron 1968, 24, 5059.