反应详情

The above prepared 5-chloro-6-hydroxy-3-methyl-benzofuran-2-carboxylic acid ethyl ester (0.700 g, 2.75 mmol) was dissolved in 12 mL of THF and treated successively at −10° C. with 1-isopropyl-piperidin-4-ol (0.551 g, 1.4 eq.), triphenylphosphine (1.001 g, 1.4 eq.) and DIAD (0.755 mL, 1.4 eq.), and the mixture then kept at ambient temperature for another 4 h. Pouring onto crashed ice/NH4Cl, twofold extraction with AcOEt, washing with water and brine, drying over magnesium sulfate, and evaporation of the solvents, followed by flash chromatography (SiO2, NEt3/AcOEt=2/98), produced 0.990 g of the title compound as light yellow gum.

1. additionPouring
2. extractionice/NH4Cl, twofold extraction with AcOEt
3. washwashing with water and brine
4. dry with materialdrying over magnesium sulfate, and evaporation of the solvents