Carbamate → tetrahydro-2H-pyran-4-yl 4-(2-fluoro-3-(3-(6-methylpyridin-3-yl)ureido)benzyl)piperazine-1-carboxylate

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Reaction Steps

To a solution of tert-butyl 4-(2-fluoro-3-(3-(2-methylpyridin-4-yl)ureido)benzyl)piperazine-1-carboxylate (1.0 g, 2.26 mmol, 1.0 equiv) in MeOH (10 mL) was added HCl (71 (4N in dioxane, 10 mL, 40 mmol, 17.7 equiv). The mixture was stirred for 30 min, and the solvent was then removed in vacuo. The residue was suspended in dry DCM (20 mL) and Et3N (1.64 mL, 11.79 mmol, 5.2 equiv). To the resulting mixture was added 4-nitrophenylchloroformate (500 mg, 2.49 mmol, 1.1 equiv). The resulting solution was stirred for 30 min, diluted with DCM, washed with aq NH4Cl and brine and concentrated in vacuo. The resulting residue was divided into three equal portions for subsequent derivitization. To a solution of 4-hydroxytetrahydropyran (190 μL, 2 mmol, 2.65 equiv) was added NaH (120 mg of 60% dispersion in mineral oil, 3.0 mmol, 4 equiv) after stirring for 10 minutes, the activated carbamate was added to the reaction mixture, and the reaction was stirred at room temperature overnight. The excess NaH was quenched by the careful addition of water, and the reaction mixture was diluted with ethyl acetate. The organic layer was washed repeatedly with water and once with brine, dried over sodium sulfate, and concentrated in vacuo. Purification by preparative reverse phase HPLC provided tetrahydro-2H-pyran-4-yl4-(2-fluoro-3-(3-(6-methylpyridin-3-yl)ureido)benzyl)piperazine-1-carboxylate (140 mg, 39%). LCMS m/z (APCI)=472.2 (M+H).

Provenance & Evidence