“…Such thermal formation of thietanes was shown to be possible when benzotriazoles [247] or acids [248] were present as reaction groups instead of alcohol functions (Scheme 3.138). Thietan-2-ones are formed by the reaction of 3-mercaptocarboxylic acids with DCC [249], i butyl chloroformate [250], methyl chloroformate [251], Ac 2 O [252], diethyl cyanophosphonate [253] or 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDAC) (Scheme 3.139) [254].…”