反应详情

A solution of 3-methoxycarbonylmethylsulfanyl-propionic acid methyl ester (32) (58 g, 300 mmol) in dry T HF (800 mL) was added slowly within 4 h to a refluxing solution of hexane washed NaH (60% in mineral oil, 13.24 g, 331 mmol) in THF. The solution was further refluxed for 5 h. The solution was cooled and the solvent was evaporated. The residue was taken in water, acidified to pH˜1 by cold HCl solution, and extracted by CH2Cl2. The combined organic phase was dried over MgSO4 and concentrated under vacuum to get a viscous residue. The residue was purified by flash chromatography eluting with hexane to yield 17 g (35%) of 4-oxo-tetrahydro-thiophene-3-carboxylic acid methyl ester as colorless viscous oil which solidified on keeping overnight under vacuum. MP 51° C.; 1H NMR (400 MHz, CDCl3) δ 3.17-3.82 (m, 6.5 H), 10.94 (s, 0.5H) ppm. The isomeric mixture was used to next step without further purification.

1. temperatureThe solution was further refluxed for 5 h
2. temperatureThe solution was cooled
3. customthe solvent was evaporated
4. extractionextracted by CH2Cl2
5. dry with materialThe combined organic phase was dried over MgSO4
6. concentrationconcentrated under vacuum
7. customto get a viscous residue
8. customThe residue was purified by flash chromatography
9. washeluting with hexane