Bronsted acid-catalyzed alpha-halogenation of ynamides from halogenated solvents and pyridine-N-oxides

초록

The keteniminium ions generated from the protonation of ynamides formed reversible adducts with counter anions and pyridine-N-oxides as well as halogenated solvents. Above 80 degrees C, the halonium ions selectively undergo a rate-limiting attack by pyridine-N-oxides, leading to (E)-haloenamides in good yields.

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