反应详情

A solution of acetonitrile (30 mL) and o-thiocresol (5.0 g, 40 mmol) was heated to reflux. Neat β-propiolactone (2.8 mL, 40 mmol) was added dropwise over 5 min. Heating was continued at reflux for 20 h at which time additional β-propiolactone (2.8 mL, 40 mmol) was added in one portion. After heating for an additional 24 h, the reaction mixture was concentrated in vacuo. The resultting solid-oil mixture was treated at 23° C. with 2N aqueous NaOH (150 mL). This basic solution was washed with Et2O (2×200 mL). The separated aqueous layer was acidified with conc. aqueous HCl until pH<1. This heterogenous solution was concentrated in vacuo to half of its original volume. Then it was allowed to stand at 23° C. for 2 h. The solid product was collected by vacuum filtration, washed with H2O (20 mL), and dried under vacuum at 65° C. for 2 h to afford 3-[(2-methylphenyl)sulfanyl]propanoic acid (4.62 g, 59%) as a white powder. 1H NMR (CHCl3, 300 MHz) δ7.31 (d, 1H, J=7.0 Hz), 7.20-7.15 (m, 3H), 3.14 (t, 2H, J=7.3 Hz), 2.69 (t, 2H, J=7.4 Hz), 2.39 (s, 3H) ppm.

1. temperatureHeating
2. additionwas added in one portion
3. temperatureAfter heating for an additional 24 h
4. concentrationthe reaction mixture was concentrated in vacuo
5. additionThe resultting solid-oil mixture was treated at 23° C. with 2N aqueous NaOH (150 mL)
6. washThis basic solution was washed with Et2O (2×200 mL)
7. concentrationThis heterogenous solution was concentrated in vacuo to half of its original volume
8. filtrationThe solid product was collected by vacuum filtration
9. washwashed with H2O (20 mL)
10. customdried under vacuum at 65° C. for 2 h