439114-13-3

439114-12-2

439114-13-3

The general procedure for the synthesis of 4,7,10,13,16-pentaoxa-nineteenthane-1,19-dioic acid from di-tert-butyl 4,7,10,13,16-pentaoxa-nineteenthane-1,19-dioic acid is as follows: tert-butyl 3-{2-[2-[2-(2-{2-[2-(2-tert-butyloxycarbonyl-ethoxy)ethoxy]ethoxy]-ethoxy}-ethoxy)-ethoxy]-ethoxy}-propionate (6 g, 18.6 mmol) was dissolved in anisole (20 ml) and cooled in an ice bath. Subsequently, trifluoroacetic acid (65 g) was added slowly. The reaction mixture was stirred at room temperature for 3 hours and the volatiles were removed by distillation under reduced pressure. The residue was extracted by partitioning between ethyl acetate (50 ml) and 5% sodium bicarbonate solution. The aqueous layer was acidified with 1N HCl to pH<2, then saturated with NaCl and extracted with ethyl acetate (3 x 50 ml). The organic layers were combined, washed with saturated brine and dried with anhydrous sodium sulfate. Finally, the solvent was removed by distillation under reduced pressure to afford the target product 4,7,10,13,16-pentaoxadecane-1,19-dioic acid as a colorless liquid, which solidified to a white solid after refrigeration (3.8 g, 82% yield).