Trifluoroacetic acid → (2-pyridyldithio)-PEG4 acid

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Reaction Steps

To a solution of 140 mg of 15-(2-pyridyldithio)-4,7,10,13-tetraoxapentadecanoic acid tert-butyl ester (13a) in 5 ml of dichloromethane was added 1.0 ml of TFA and 250 μl of Et3SiH. After stirring for 2 hrs, the mixture was diluted with 5 ml of toluene. The mixture was evaporated and then co-evaporated three times with 5 ml of toluene and dried under vacuum to yield of 122 mg (99% yield) of the title compound 14a (FIG. 7). 1H NMR (CDCl3) 13.331 (s, OH), 8.770 (d, 1H, J=5.4 Hz), 8.299 (t, 1H, J=7.7+7.7 Hz), 8.130 (d, 1H, J=8.2 Hz), 7.677 (t, 1H J=6.3+6.4 Hz), 3.703˜3.556 (m, 16H), 3.109 (t, 2H, J=6.4+6.4 Hz), 2.538 (t, 2H, J=6.1+6.1 Hz); 13C NMR 175.900, 157.402, 144.807, 129.114, 124.746, 123.635, 70.452, 70.327, 70.206, 70.184, 69.881, 69.862, 67.229, 66.407, 39.320, 34.866; MS 392.73 (M+H)+, 390.76 (M−H)−.

Provenance & Evidence