10.1002/chem.201902147
Chemistry - A European Journal
COMMUNICATION
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with ammonia. Under very mild conditions, monoarylated
products are obtained in high yields with the lowest catalyst
loading reported so far. For the first time, chloropyridines bearing
a strongly deactivating amino group have been successfully
employed as substrates, with the scope not limited to the more
reactive 2-chloropyridines but remarkably also including the
challenging 3- and 4-chloro regioisomers. Noteworthy features of
this catalytic system include tolerance of functional groups such
as Boc, free amines and sulfur-containing heterocycles and the
use of a well-defined pre-catalyst with the valuable 1:1 ligand to
palladium ratio. The herein presented methodology is the key
enabler of the efficient and cost effective two-step access to
diaminopyridine building blocks, a synthetic strategy that not only
offers significant advantages compared to classical routes, but
also provides access to an extended array of these highly relevant
structures.
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Acknowledgements
We thank Annick Becht Joerger, Isabelle Duffour, Olga Fuchs &
the Structure Analytics team for their support with compounds
characterization and Daniel Spiess for the synthesis of the
catalyst.
Keywords: Amination • Heterocycles • Homogeneous catalysis •
Palladium • Synthetic methods
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