TMSCH(2)Li and TMSCH(2)Li-LiDMAE: efficient reagents for noncryogenic halogen-lithium exchange in bromopyridines |
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Authors: | Doudouh Abdelatif Woltermann Christopher Gros Philippe C |
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Institution: | Synthèse Organométallique et Réactivité, UMR CNRS 7565, Nancy Université, Université Henri Poincaré, Boulevard des Aiguillettes, 54506 Vandoeuvre-lès-Nancy, France. |
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Abstract: | 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. |
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