Iodoethane → 2-Ethoxy-4-fluorobenzaldehyde

Beteiligte Stoffe

Reaktionsschritte

In analogy to the procedure described in example 17 a], [rac]-2-ethoxy-3-(4-hydroxy-benzo[b]thiophen-7-yl)-propionic acid methyl ester was reacted with 2-[2-(2-ethoxy-4-fluoro-phenyl)-5-methyl-oxazol-4-yl]-ethanol (prepared from 4-fluoro-2-hydroxy-benzaldehyde [J. Chem. Soc., Perkin Trans. 1 (1994), (13), 1823-31] by i) treatment with ethyl iodide, potassium carbonate in N,N-dimethylformamide to give 2-ethoxy-4-fluoro-benzaldehyde; ii) conversion of the 2-ethoxy-4-fluoro-benzaldehyde into 2-[2-(2-ethoxy-4-fluoro-phenyl)-5-methyl-oxazol-4-yl]-ethanol in analogy to the sequence described in examples 21 a] to 21 e]) in the presence of triphenylphosphine and DEAD (diethyl azodicarboxylate) to yield [rac]-2-ethoxy-3-(4-{2-[2-(2-ethoxy-4-fluoro-phenyl)-5-methyl-oxazol-4-yl]-ethoxy}-benzo[b]thiophen-7-yl)-propionic acid methyl ester, which was further saponified in analogy to the procedure described in example 91 e] to yield [rac]-2-ethoxy-3-(4-{2-[2-(2-ethoxy-4-fluoro-phenyl)-5-methyl-oxazol-4-yl]-ethoxy-}-benzo[b]thiophen-7-yl)-propionic acid as light yellow solid.

Herkunft & Nachweise