反应详情

Under N2, a mixture of 2-methylene-4-ethoxycarbonylbutyric acid (17 g, 0.09 mol), triethylamine (4.3 g, 0.04 mol) in THF (120 ml) and 2-mercaptothiophene (11 g, 0.095 mol) was heated at reflux. After 24 hours the reaction mixture was cooled to room temperature and poured into 3N HCl (400 ml). The aqueous layer was extracted with EtOAc (3×) and the combined organic extracts were backwashed with saturated NaCl, dried, filtered and concentrated to dryness. The residue was chromatographed on a Still column and the product eluted with 15% CH3OH-CHCl3 saturated with NH3 to yield 14 g of 1 wherein R1, R2, R3 and R4 are each H.

1. temperaturewas heated
2. temperatureat reflux
3. extractionThe aqueous layer was extracted with EtOAc (3×)
4. customdried
5. filtrationfiltered
6. concentrationconcentrated to dryness
7. customThe residue was chromatographed on a Still column
8. washthe product eluted with 15% CH3OH-CHCl3 saturated with NH3