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Updated: Aug 26, 2025

Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
Published on: March 20, 2017
Continuous-Flow Divergent Lithiation of 2,3-Dihalopyridines: Deprotolithiation versus Halogen Dance
Thibaud Brégent1, Maria V Ivanova1, Thomas Poisson1,2
1Normandie Univ., INSA Rouen, UNIROUEN, CNRS, COBRA (UMR 6014), 76000, Rouen, France.
Abstract:
We describe herein the first halogen dance (HD) in continuous flow on 2-chloro-3-bromopyridine by selectively trapping a (pyridin-4-yl)lithium species that is known to undergo the halogen-dance process. In addition, this lithiated intermediate was trapped at lower temperature before the HD occurs. The HD process was extended to fluoro-iodopyridines by using various electrophiles to afford 28 examples with yields ranging from 42 to 97 % with very short residence times. Finally, scale up of the reaction was demonstrated, affording a promising space-time yield (STY) of 4.2 kg.h-1 .L-1 .
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