Carbamate → Trifluoroacetic acid

Participants

Reaction Steps

To a solution of the title compound from Example 11 Step C (200 mg, 0.278 mmol) in DCM (3 mL) was added TFA (1 mL). After 10 min, the reaction mixture was concentrated in vacuo, and the crude TFA salt was used without further purification: LCMS m/z 618.8 [M+H]+. To a portion of the crude TFA salt in DCM (1.5 mL) were added DIEA (486 μL, 2.78 mmol) and methyl chloroformate (65 μL, 0.84 mmol), and the resulting mixture was allowed to stir at room temperature. After 90 min, the reaction mixture was quenched by addition of sat aq NaHCO3 and the aqueous phase was extracted with DCM. The organic phase was separated and concentrated in vacuo to provide the crude carbamate, which was used without further purification: LCMS m/z 676.8 [M+H]+. To a solution of the carbamate in dioxane (3 mL) was added lithium hydroxide (1.5 mL, 2N aqueous, 3 mmol), and the mixture was stirred at 50° C. After 1 h, the reaction mixture was rendered acidic by addition of HCl (2N aqueous), then was diluted with acetonitrile and purified by reverse phase HPLC (30 to 100% acetonitrile/water, both 0.1% v/v TFA) to provide the title compound: LCMS m/z 648.8 [M+H]+; 1H NMR (500 MHz, d6-DMSO) δ 8.29 (s, 1H), 8.07 (t, J=8.0 Hz, 1H), 8.03 (d, J=8.0 Hz, 1H), 7.72-7.69 (m, 2H), 7.62-7.61 (m, 2H), 7.54-7.52 (m, 1H), 7.47-7.43 (m, 1H), 7.24 (d, J=8.5 Hz, 1H), 7.13 (t, J=8.5 Hz, 1H), 5.32 (s, 2H), 4.14-4.08 (m, 2H), 3.60 (s, 3H), 2.88-2.80 (m, 3H), 1.78-1.75 (m, 2 H), 1.58-1.49 (m, 2H).

Provenance & Evidence