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DOI: 10.1055/sos-SD-026-00397

Salaün, J.Science of Synthesis, (200526557.

5,9-Dithiaspiro[3.5]nonane (2) is formed in 6584% yield from the reaction of the 2-lithiated derivative of 1,3-dithiane (1)[‌7‌] with 1-bromo-3-chloropropane, followed by butyllith­ium-induced cyclization of the resulting 2-(3-chloropropyl)-1,3-dithiane intermediate. Cyclobutanone (3) is obtained in 6081% yield after the protecting group of cyclobutanone dithioacetal 2 has been cleaved by treatment with an excess of mercury(II) chloride in triethylene glycol and water (Scheme 1).[‌8‌] Use of 1,3-dibromopropane is unsuitable because it entails the formation of cyclic sulfonium bromides.[‌9‌]

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