4-Toluenesulfonyl chloride → Tos-PEG4-t-butyl ester

Participants

Reaction Conditions

Reaction Steps

Into a 250-mL round-bottom flask purged and maintained with an inert atmosphere of nitrogen, was placed a solution of tert-butyl 3-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)propanoate (intermediate 179.1) (9.6 g, 34.49 mmol, 1.00 equiv) in anhydrous pyridine (12 mL). The mixture was cooled to 0° C. and 4-methylbenzene-1-sulfonyl chloride (7.9 g, 41.44 mmol, 1.20 equiv) was added slowly in several portions. The resulting solution was stirred at 0° C. for 1-2 h and then the flask containing the reaction mixture was sealed and placed in a refrigerator at 0° C. overnight. The mixture was poured into 120 mL of water/ice, and the aqueous layer was extracted with 3×50 mL of DCM. The combined organic layers were washed with 2×50 mL of cold 1.0 N hydrogen chloride and saturated brine and dried over anhydrous sodium sulfate. The solvent was removed under vacuum to yield 13.4 g (90%) of tert-butyl 3-(2-(2-(2-(tosyloxy)ethoxy)ethoxy)ethoxy)propanoate as pale yellow oil.

Provenance & Evidence