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Please login to access the full content or check if you have access via Variation 1: Dehydration of Carboxylic Acids Using Mukaiyama's Reagent

DOI: 10.1055/sos-SD-023-00535

Tidwell, T. T.Science of Synthesis, (200623572.

The direct dehydration of alkanoic acids can be achieved with specialized reagents, as in the reaction of 6-oxohexanoic acid (15) with 2-chloro-1-methylpyridinium iodide (Mukaiyama's reagent; 16) in the presence of 9-O-acetylquinine as a catalyst to give the β-lactone 18 (52%, 92% ee; Scheme 5). This reaction may involve the non-observed ketene 17, which cyclizes to form the β-lactone 18.[‌51‌] The formation of a free ketene in this reaction has not been proved, and there are various other mechanistic possibilities, such as cyclization via an acyl ammonium enolate.[‌51‌] An analogous reaction involving a putative dialkylketene is discussed in Section

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