Chlorosulfonic acid → 2-(4-Tolylsulfonyl)ethyl 4-chlorosulfonyl-2-(2-[4-tolylsulfonyl]ethoxycarbonylmethoxy)phenoxyacetate

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Reaction Conditions

Reaction Steps

{2-[2-(Toluene-4-sulfonyl)-ethoxycarbonylmethoxy]-phenoxy}-acetic acid 2-(toluene-4-sulfonyl)ethyl ester (Intermediate 37) (13 g, 22 mmole) was added to dichloromethane (30 mL), and cooled in an ice bath. Chlorosulfonic acid (10 mL) was slowly added, and the mixture was stirred at 0° C. for 2 hr., then at room temperature for 1 hr. Thereafter it was poured into crushed ice (200 g) with stirring. The precipitates were extracted with dichloromethane. The dichloromethane layer was dried over anhydrous magnesium sulfate and concentrated, the residue was dried in vacuo to yield 17.3 g of {4-chlorosulfonyl-2-[2-(toluene-4-sulfonyl)-ethoxycarbonylmethoxy]-phenoxy}-acetic acid 2-(toluene-4-sulfonyl)ethyl ester (Intermediate 38).

Provenance & Evidence