TMSCH(2)Li and TMSCH(2)Li-LiDMAE: efficient reagents for noncryogenic halogen-lithium exchange in bromopyridines

TMSCH(2)Li and TMSCH(2)Li-LiDMAE: efficient reagents for noncryogenic halogen-lithium exchange in bromopyridines

TMSCH(2)Li and TMSCH(2)Li-LiDMAE have been used efficiently for bromine-lithium exchange in 2-bromo-, 3-bromo-, and 2,5-dibromopyridines under noncryogenic conditions, while low temperatures (-78 to -100 degrees C) are always needed with n-BuLi. The aminoalkoxide LiDMAE induced a remarkable C-2 sele...

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Veröffentlicht in:Journal of organic chemistry 2007-06, Vol.72 (13), p.4978-4980
Hauptverfasser: Doudouh, Abdelatif, Woltermann, Christopher, Gros, Philippe C
Format: Artikel
Sprache:eng
Schlagworte:
Bromine - chemistry
Lithium - chemistry
Lithium Compounds - chemistry
Molecular Structure
Pyridines - chemical synthesis
Pyridines - chemistry
Trimethylsilyl Compounds - chemistry
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Zusammenfassung:TMSCH(2)Li and TMSCH(2)Li-LiDMAE have been used efficiently for bromine-lithium exchange in 2-bromo-, 3-bromo-, and 2,5-dibromopyridines under noncryogenic conditions, while low temperatures (-78 to -100 degrees C) are always needed with n-BuLi. The aminoalkoxide LiDMAE induced a remarkable C-2 selectivity with 2,5-dibromopyridines in toluene at 0 degrees C, which was unprecedented at such a temperature. The lithiopyridines were successfully reacted with electrophiles also under noncryogenic conditions giving the expected adducts in good yields.
ISSN:0022-3263