Trifluoroacetic acid → p-Toluenesulfonic acid

Participants

Reaction Steps

To a solution of the product of Example 12B (0.33 g, 0.58 mmol) in CH2Cl2 (4 mL) was added trifluoroacetic acid (2 mL, 26 mmol). This mixture stirred at ambient temperature for 2 h then was concentrated under reduced pressure and purified via column chromatography (SiO2, 100% CH2Cl2 to 9:1:0.1 CH2Cl2:CH3OH:NH4OH). The material was dissolved in hexanes/EtOAc (1 mL/2 mL) and one equivalent of p-toluenesulfonic acid monohydrate in 1 mL EtOAc was added. Solids precipitated immediately and the p-toluenesulfonic acid salt of the title compound was isolated via filtration (0.13 g, 0.20 mmol, 35% yield). 1H NMR (300 MHz, CD3OD) δ ppm 0.99 (dd, J=6.8, 2.4 Hz, 6H), 1.39 (s, 9H), 2.24-2.34 (m, 1H), 2.36 (s, 3H), 2.58-2.80 (m, 2H), 4.04-4.20 (m, 4H), 4.35-4.42 (m, 1H), 4.49-4.56 (m, 1H), 4.86-4.95 (m, 1H), 7.18-7.25 (m, 3H), 7.34 (d, J=8.5 Hz, 1H), 7.68-7.71 (m, 2H), 7.79 (dd, J=8.6, 1.9 Hz, 1H), 8.38 (d, J=2.4 Hz, 1H); MS (DCI/NH3) m/z 470 (M+H)+. Anal. calculated for C23H30F3N3O2S.1.5 C7H8O3S.1.2H2O: Calc: C, 53.69; H, 5.97; N, 5.61. Found: 53.38; H, 6.13; N, 5.91.

Provenance & Evidence