反应详情

温度

-74 °C

Procedure B (from (122a), without isolation of the sulfonyl chloride (122b). A solution of the allyl-protected thiophene (1a) (29.1 g, 150 mmol) in Et2O (440 g, 617 ml) was placed in a 1-1 three-necked flask (thermometer; argon; septum or SO2 inlet) and cooled to −74° C. by means of an acetone/dry ice bath. A solution of t-BuL in pentane (100 ml, 1.5M, 150 mmol) was added over 5 min whereupon the internal temperature momentarily rose to −64° C. and the mixture turned pink. After 20 min., SO2 (20 g, 312 mmol) was bubbled over 15 min. The SO2 consumption was best monitored by placing the SO2 bottle on a scale during the reaction The reaction mixture, which had turned to a thick, white wax was allowed to warm to room temperature over 2 h. A suspension of NCS (30 g, 226 mmol) was added, and stirring was continued overnight, whereupon the slurry turned purple. The mixture was filtered (fritted glass), and the precipitate was carefully washed with CH2Cl2 (2×300 ml). The combined organic layers were cooled to 0° C. under Ar, and treated with a solution of 1,4-dioxa-8-azaspiro[4,5]decane (27.8 g, 194 mmol) and triethylamine (19.7 g, 194 mmol) in CH2Cl2 (200 ml). After 1 h, the mixture was washed (NaHCO3 sat.; brine), dried (MgSO4), and concentrated to afford 53 g (83%) of the title sulfonamide as yellow oil: 1H NMR (CDCl3) δ7.36 (d, J=3.8 Hz, 1H), 6.90 (br. d, J=3.4 Hz, 1H), 5.92-5.79 (m, 2H), 5.33-5.16 (m, 4H), 3.93 (s, 4H), 3.78 (s, 2H), 3.21 (t, 5.7 Hz, 4H), 3.13 (d, 6.2 Hz, 4H), 1.81 (t, 5.7 Hz, 4H).

1. custommomentarily rose to −64° C.
2. customSO2 (20 g, 312 mmol) was bubbled over 15 min
3. customThe SO2 consumption
4. customduring the reaction The reaction mixture, which
5. temperatureto warm to room temperature over 2 h
6. additionwas added
7. waitwas continued overnight, whereupon the slurry
8. filtrationThe mixture was filtered (fritted glass)
9. washthe precipitate was carefully washed with CH2Cl2 (2×300 ml)
10. temperatureThe combined organic layers were cooled to 0° C. under Ar
11. waitAfter 1 h
12. washthe mixture was washed (NaHCO3 sat.; brine)
13. dry with materialdried (MgSO4)
14. concentrationconcentrated