Nitrogen → (E)-ethyl 2-(1-phenylprop-1-en-2-yl)oxazole-4-carboxylate

Participants

Reaction Steps

In a flame dried round-bottomed flask equipped with a magnetic stir bar and under inert atmosphere (N2), a suspension of (E)-2-methyl-3-phenylacrylamide (29.4 g, 0.18 mol) and NaHCO3 (68.7 g, 0.82 mol) in THF (500 mL) was treated with 3-bromo-2-oxo-propionic acid ethyl ester (35.6 mL, 0.24 mol) and the reaction mixture was heated at reflux for 20 h. 3-Bromo-2-oxo-propionic acid ethyl ester (10.0 mL, 0.68 mol) was added again and the reaction mixture was stirred at reflux for 10 h. The reaction mixture was then filtered over celite and the solvents were evaporated under reduced pressure. The residue was dissolved in THF (500 mL) and treated at 0° C., dropwise, with trifluoroacetic anhydride (78.0 mL, 0.55 mol). The reaction mixture was then stirred at rt overnight. Sat. aq. Na2CO3 was added and the mixture was extracted with EA (4×), dried over MgSO4, filtered, and the solvent was removed under reduced pressure. Purification of the residue by FC (0:1->1:9 EA-Hept) gave the title compound as a brown oil. TLC:rf (1:9 EA-Hept)=0.13. LC-MS-conditions 01: tR=1.02 min; [M+H]+=257.97.

Provenance & Evidence