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Please login to access the full content or check if you have access via Variation 1: Dehydrochlorination Using a Shuttle Procedure with a Kinetic Base and a Stoichiometric Base

DOI: 10.1055/sos-SD-023-00535

Tidwell, T. T.Science of Synthesis, (200623577.

The dehydrohalogenation of alkylacetyl chlorides by triethylamine to form alkylketenes is complicated by the reaction of the alkylketenes with the amine to form acylammonium enolates, and by the catalysis of ketene reactions by the triethylammonium chloride that is produced in the reaction.[‌36‌] These difficulties have been circumvented by the use of procedures involving a strong stoichiometric base and a catalytic amount of a kinetically efficient base, such as triethylamine, or a chiral base, such as 9-O-benzoylquinine. These act as shuttle bases by abstracting a proton from the acyl chloride to form the ketene. A proton is then transferred to the stoichiometric base and together these irreversibly dehydrochlorinate the acyl chloride at low temperatures.[‌38‌‌46‌] With some bases, the intermediacy of ketenes has not been proved, because there is the possibility of reversibility of ketene formation, but with other bases, such as sodium hydride, ketene formation is irreversible.

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Meeee eee-8-Meeee-8-eee-8-eeeeeeeeeeeeee-8-eeeeeeeeeee (88):[‌88‌]

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