Diisopropylethylamine → tert-Butyl 4-(2-oxobenzo[d]oxazol-3(2H)-yl)piperidine-1-carboxylate

Participants

Reaction Steps

To a stirred 0° C. solution of 1-t-Butyloxycarbonyl-4-(2-hydroxyphenylamino)piperidine (3.0 g, 10 mmol) from Step 1 of Example 41 in dry THF (40 mL) was added DIEA (5.2 mL, 30 mmol), followed by triphosgene (1.08 g, 3.60 mmol). After 30 min, the reaction was warmed to ambient temperature and stirred for 24 h. The precipitated hydrochloride salt of DIEA was removed by filtration and the solvent was removed under reduced pressure. The residue was dissolved in EtOAc (200 mL) and washed with saturated aqueous NaHCO3 (2×100 mL), water (100 mL), 5% aqueous citric acid (100 mL), and brine (100 mL). The EtOAc layer was dried (MgSO4), filtered, and the solvent was removed under reduced pressure. 3-(1-t-Butyloxycarbonyl-4-piperidinyl)benzoxazolidin-2-one was obtained as a solid (82% yield).

Provenance & Evidence