Trichloroacetyl chloride → tert-Butyl 5,5-dichloro-6-oxo-2-azaspiro[3.3]heptane-2-carboxylate

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Reaction Steps

28.42 mL (254.65 mmol) of trichloroacetyl chloride dissolved in 70 mL of dimethoxyethane are added dropwise, at 0° C., to a mixture containing 7.98 g (47.16 mol) of tert-butyl 3-methyleneazetidine-1-carboxylate (WO 2008/124 085) and 36.48 g (282.94 mmol) of zinc-copper amalgam suspended in 200 mL of ether. The reaction medium is stirred at room temperature for 12 hours. The mixture is then poured portionwise into a sodium carbonate solution at 0° C. The solution obtained is filtered through Celite and rinsed thoroughly with water and ether. The aqueous phase is then separated out and extracted several times with ether. The combined organic phases are dried over sodium sulfate and the filtrate is concentrated under reduced pressure. After evaporating off the solvent, the product obtained, in the form of a brown oil, is used without further purification in the following step.

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