Trifluoroacetic acid → Trifluoroacetate

Participants

Reaction Steps

A solution of Example 319A (50 mg, 0.13 mmol) in a mixed solvent of 1,2-dichloroethane (1 ml) and acetic acid (0.5 ml) was added nicotinaldehyde (20 mg, 0.19 mmol). The mixture was stirred at room temperature for 2 hours and sodium triacetoxyborohydride (40 mg, 0.19 mmol) was added. The mixture was stirred overnight. The reaction mixture was partitioned between water and ethyl acetate. The organic phase was concentrated and purified by flash chromatography on silica gel using an ISCO Companion eluting with heptanes/ethyl acetate (30%) to give Boc-protected intermediate which was dissolved in CH2Cl2 (10 mL) then treated with trifluoroacetic acid (1 mL). The mixture was stirred at room temperature for 5 hours and concentrated. The residue was purified by reverse-phase HPLC on Zorbax XDB C-18 using a gradient of 5-40% acetonitrile/water (containing 0.1% trifluoroacetic acid) to afford the title compound as a trifluoroacetate salt. 1H NMR (400 MHz, DMSO-d6) δ 1.64-1.86 (m, 2H), 2.02-2.25 (m, 2H), 3.05 (dd, J=13.0, 8.4 Hz, 3H), 3.38 (d, J=12.4 Hz, 2H), 4.77 (d, J=4.5 Hz, 2H), 6.57 (s, 1H), 7.51 (d, J=5.1 Hz, 1H), 7.77 (dd, J=8.0, 5.3 Hz, 1H), 8.12 (s, 1H), 8.24 (t, J=6.3 Hz, 2H), 8.45 (s, 1H), 8.68 (d, J=5.3 Hz, 1H), 8.82 (s, 1H). MS (ESI+) m/z 386 (M+H)+.

Provenance & Evidence