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Updated: Aug 7, 2026

A Protocol for Safe Lithiation Reactions Using Organolithium Reagents
Published on: November 12, 2016
When ethyl is infinitely different from methyl: double addition of lithiated dithianes to aromatic carboxylates
Roman A Valiulin1, Rudresha Kottani, Andrei G Kutateladze
1Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208-2436, USA.
Abstract:
Addition of lithiated alkyl dithianes to benzoyl chloride or methyl benzoate does not produce the expected product of double addition, alpha,alpha-bis(alkyldithianyl) benzyl alcohol, for alkyls larger than methyl. Instead, the first step intermediate, i.e. 2-benzoylated dithiane, undergoes an electron-transfer reduction by the second molecule of the dithianyl anion. This reduction is followed by the ring-opening mesolytic fragmentation of the dithiane ring in the ketyl anion radical and subsequent radical recombination yielding acetophenone-tethered thioortho esters 4, alpha-[3-(2-alkyl-1,3-dithiane-2-ylthio)propylthio]-alpha-alkyl-acetophenones. It appears that the Corey-Seebach bisaddition of lithiated dithianes to methyl benzoate is an exception rather than the rule in the alkyl dithiane series.
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