Formaldehyde → 2-(Chloromethyl)-4-isopropyl-6-methoxybenzo[D]isothiazol-3(2H)-one 1,1-dioxide

Beteiligte Stoffe

Reaktionsschritte

To a suspension of paraformaldehyde (24 g) and chlorotrimethylsilane (86.4 g) in 1,2-dichloroethane (200 mL) was added dry tin(IV) chloride (0.8 mL) and the resulting solution was stirred on a steam bath for one hour. 4-Isopropyl-6-methoxysaccharin (51.4 g) was added to the clear solution and the mixture was refluxed for 18 hours, cooled to room temperature and poured into water. The organic layer was separated, washed with aqueous sodium hydroxide solution (2N, 50 mL), dried over magnesium sulfate and concentrated under vacuum. The residue was crystallized from ethyl acetate-hexane to give 2-chloromethyl-4-isopropyl-6-methoxysaccharin (57 g, 87% yield, m.p. 151° C.).

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