Chlorosulfonic acid → [2-(2-Benzenesulfonyl-ethoxycarbonylmethoxy)-4-chlorosulfonyl-phenoxy]-acetic acid 2-benzenesulfonyl-ethyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of [2-(2-benzenesulfonyl-ethoxycarbonylmethoxy)phenoxy]acetic acid 2-benzenesulfonyl-ethyl ester (Intermediate 28, 7.4 g, 13.2 mmol) in 10 mL of CH2Cl2 was added drop-wise ClSO3H (5.0 mL, 8.8 g, 75.8 mmol, 5.7 eq) at 0° C. with vigorous stirring. The mixture was stirred at 0° C. for 1.5 h. and then poured onto crushed ice with vigorous stirring, resulting in a thick mass. This was extracted with CH2Cl2. The organic layers were dried and concentrated under reduced pressure. The residual oil was dried under vacuum overnight to give Intermediate 29 (8.0 g, 92%) as an off-white foam.

Provenance & Evidence