Thionyl Chloride → 5-(Chloromethyl)-2,2-difluorobenzo[d][1,3]dioxole

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Reaction Steps

A solution of (2,2-difluorobenzo[d][1,3]dioxol-5-yl)methanol (120 g, 0.64 mol) in neat thionyl chloride (500 mL) was stirred for 2 h at 25° C. The excess thionyl chloride was distilled off in vacuo. The residue was partitioned between saturated NaHCO3 (400 mL) and dichloromethane (200 mL). The separated aqueous layer was extracted with dichloromethane (300 mL×3). The combined organic layers were dried, filtered and concentrated in vacuo to give 5-(chloromethyl)-2,2-difluorobenzo[d][1,3]dioxol (117.6 g, 89%), which was directly used in the next step.

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