General procedure for the synthesis of propargyl-monoethylene glycol-carboxylic acid from tert-butyl 3-(prop-2-yn-1-yloxy)propionate: trifluoroacetic acid (8.065 mL, 108.6 mmol) was added to a solution of tert-butyl 3-(prop-2-yn-1-yloxy)propionate (2.0 g, 10.86 mmol) in dichloromethane (50 mL). The reaction mixture was stirred overnight at room temperature and subsequently concentrated under vacuum, co-evaporated with toluene and purified by fast chromatography on 80 g silica gel (using a dichloromethane/methanol gradient elution) to afford 1.1 g of propargyl-monoethyleneglycol-carboxylic acid as an oil (80% yield).1H NMR (400 MHz, DMSO-d6, δ, ppm): 2.46 (t J = 6.4 Hz, 2H); 3.43 (t, J = 2.4 Hz, 1H); 3.63 (t, J = 6.4 Hz, 2H); 4.11 (d, J = 2.4 Hz, 2H); 12.20 (broad peak, 1H).
