Diisopropylethylamine → N-(2-tert-butoxycarbonylamino-5-trifluoromethyl-phenyl)-malonamic acid benzyl ester

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Reaction Steps

The compound (2-amino-4-trifluoromethyl-phenyl)-carbamic acid tert-butyl ester (1.8 g, 6.6 mmol, see procedure 4a) was dissolved in 32 mL of 2:1 CH2Cl2/DMF. The resultant solution was charged sequentially with mono-benzyl malonate (1.28 g, 6.6 mmol), N,N-diisopropylethylamine (5.8 mL, 33 mmol) and HATU (3.0 g, 7.9 mmol). The mixture was stirred for 12 h at RT, concentrated in vacuo, and partitioned between EtOAc and sat. NH4Cl. The aqueous phase was extracted with EtOAc (1×). The combined organic extracts were washed with sat. NaHCO3 and brine, dried (Na2SO4), filtered, and concentrated in vacuo. The residue was purified by flash chromatography to provide N-(2-tert-butoxycarbonylamino-5-trifluoromethyl-phenyl)-malonamic acid benzyl ester (2.3 g, 77% yield). A portion (860 mg) of this material was dissolved in 10 mL of THF. The resultant solution was charged with 30 mL of acetic acid, heated at 65° C. for 3 h, and concentrated in vacuo. The residue was purified by flash chromatography to provide (5-trifluoromethyl-1H-benzoimidazol-2-yl)-acetic acid benzyl ester (343 mg, 54% yield). MS found: (M+H)+=335.2.

Provenance & Evidence