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Regiochemically flexible substitutions of di-, tri-, and tetrahalopyridines: the trialkylsilyl trick.
Journal article

Regiochemically flexible substitutions of di-, tri-, and tetrahalopyridines: the trialkylsilyl trick.

  • Schlosser M Institute of Chemical Sciences and Engineering (ISIC-BCh), Ecole Polytechnique Fédérale, CH-1015 Lausanne, Switzerland. schlosser@epfl.ch
  • Bobbio C
  • Rausis T
  • 2005-03-25
Published in:
  • The Journal of organic chemistry. - 2005
Organic Chemistry
English [reactions: see text] 2,4-Difluoropyridine, 2,4-dichloropyridine, 2,4,6-trifluoropyridine, 2,4,6-trichloropyridine and 2,3,4,6-tetrafluoropyridine react with standard nucleophiles exclusively at the 4-position under halogen displacement. However, the regioselectivity can be completely reversed if a trialkylsilyl group is introduced in the 5-position of the 2,4-dihalopyridines or in the 3-position of the 2,4,6-trihalopyridines or 2,3,4,6-tetrahalopyridine. Then only the halogen most remote from the bulky silyl unit (at the 2-position in the case of the 2,4-halopyridines, at the 6-position with the other substrates) gets involved in the exchange process. After removal of the silyl protective group the nucleophile is invariably found to occupy the nitrogen-neighboring position.
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  • English
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closed
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https://sonar.ch/global/documents/14130
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