反应详情

In analogy to the procedure described in example 7 c], [rac]-2-ethoxy-3-(4-hydroxy-2-methyl-phenyl)-propionic acid ethyl ester (example 34 b]) 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 2-ethoxy-4-fluoro-benzaldehyde into 4-chloromethyl-2-(2-ethoxy-4-fluoro-phenyl)-5-methyl-oxazole in analogy to the procedures described in examples 2 a] and b]; iii) conversion of 4-chloromethyl-2-(2-ethoxy-4-fluoro-phenyl)-5-methyl-oxazole into 2-[2-(2-ethoxy-4-fluoro-phenyl)-5-methyl-oxazol-4-yl]-ethanol by treatment with sodium cyanide in DMSO followed by hydrolysis of the nitrile function with sodium hydroxide in ethanol/water at reflux and reduction of the acid formed with BH3×THF in tetrahydrofuran at room temperature) in the presence of triphenylphosphine and diethyl azodicarboxylate to yield [rac]-2-ethoxy-3-(4-{2-[2-(2-ethoxy-4-fluoro-phenyl)-5-methyl-oxazol-4-yl]-ethoxy}-2-methyl-phenyl)-propionic acid ethyl ester as light yellow liquid.