Nitrogen → 5-(3-Tert-butoxycarbonyl-phenyl)-oxazole-4-carboxylic acid methyl ester

Participants

Reaction Conditions

Reaction Steps

In a flame dried round-bottomed flask equipped with a magnetic stir bar and under inert atmosphere (N2), a suspension of isophthalic acid mono-tert-butyl ester (4.00 g, 18.00 mmol) and potassium carbonate sesquihydrate (6.03 g, 43.20 mmol) in DMF (36.0 mL) was treated with a solution of methyl isocyanoacetate (3.45 mL, 36.00 mmol) in DMF (6.0 mL). After 5 min, the reaction mixture was cooled to 0° C. and a solution of DPPA (4.01 mL, 18.00 mmol) in DMF (6 mL) was added dropwise. The resulting mixture was stirred at 0° C. for 2 h and then overnight at rt. A 1:1 mixture of toluene:EA (400 mL) was added and the organic layer was washed with water (150 mL), 10% aq. citric acid solution (150 mL) and sat. aq. NaHCO3 (150 mL). The organic layer was dried over MgSO4, filtered, and the solvent removed under reduced pressure. Purification of the residue by FC (60:40 hept-EA) gave the title compound as a white solid. TLC: rf (60:40 hept-EA)=0.27. LC-MS-conditions 02: tR=1.04 min, [M+H]+=304.32.

Provenance & Evidence