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Updated: Nov 5, 2025

Syntheses, Crystallization, and Spectroscopic Characterization of 3,5-Lutidine N-Oxide Dehydrate
Published on: April 24, 2018
Regioselective difunctionalization of pyridines via 3,4-pyridynes
Benjamin Heinz1, Dimitrije Djukanovic1, Paolo Filipponi2
1Ludwig-Maximilians-Universität München, Department Chemie Butenandtstraße 5-13 81377 Munich Germany paul.knochel@cup.uni-muenchen.de.
Abstract:
A new regioselective 3,4-difunctionalization of 3-chloropyridines via 3,4-pyridyne intermediates is reported. Regioselective lithiation of 3-chloro-2-ethoxypyridine and a related 2-thio-derivative followed by treatment with aryl- and alkylmagnesium halides as well as magnesium thiolates at -78 °C produced 3,4-pyridynes during heating to 75 °C. Regioselective addition of the Grignard moiety in position 4 followed by an electrophilic quench in position 3 led to various 2,3,4-trisubstituted pyridines. This method was adapted into a continuous flow set-up. As an application, we have prepared a key intermediate for (±)-paroxetine.
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