Acetic Acid → N-methyl-N-(t-Boc)-PEG4-acid

Participants

Reaction Steps

85.4 mg of NaH are added portionwise to a solution, cooled to 0° C., of 520 mg of 3-[2-(2-{2-[2-((tert-butoxycarbonyl)amino)ethoxy]ethoxy}ethoxy)ethoxy]propanoic acid in 14 ml of THF. After stirring for 5 min, 150 μl of iodomethane are added. The mixture is then stirred at AT for 2 h and then an additional 150 μl of iodomethane are added. After 12 h at AT, the mixture is hydrolysed and then brought to acidic pH by addition of aqueous acetic acid at 0° C. The aqueous phase is extracted 3× with AcOEt, the combined organic phases are dried over MgSO4 and concentrated under RP, and the crude product obtained is reacted again according to the same protocol with 85 mg of NaH and 176 μl of iodomethane for an additional 2 h. 500 mg of 3-[2-(2-{2-[2-((tert-butoxycarbonyl)(methyl)amino)ethoxy]ethoxy}ethoxy)ethoxy]propanoic acid are thus obtained.

Provenance & Evidence