反应详情

Compound 20a (78 mg, 0.25 mmol) in a 2:1 mixture (4 mL) of formic and acetic acid was treated with a 2M solution of bromomethane in diethyl ether (5 mL) and stirred for 6 days in darkness at room temperature. Solvents were removed in vacuo and a solution of the residue in water (10 mL) was extracted with (3×10 mL) ether. The aqueous layer was concentrated to dryness. The resulting product was dissolved in MeOH (10 mL), filtered and treated with diethyl ether to precipitate out the salt. The salt was filtered, washed with ether, and dried in vacuo to give white solid: yield 79 mg (78%); MS m/z 326 (M)+; 1HNMR (D2O) δ 8.24 (s, 1H, H-2), 6.03 (d, 1H, H-1′, J1′,2′=5.4 Hz), 5.29 (t, 1H, H-2′, J2′,3′=5.7 Hz), 4.80 (t, 1H, H-3′, J3′,4′=4.8 Hz), 4.52-4.60 (m, 1H, H-4′), 4.11-4.20 (m, 1H, 5′-CH2), 3.81-3.90 (m, 1H, 5′-CH2), 2.92 and 2.89 (2s, 6H, S—(CH3)2), 2.67 (s, 3H, 8-CH3).

1. customSolvents were removed in vacuo
2. extractiona solution of the residue in water (10 mL) was extracted with (3×10 mL) ether
3. concentrationThe aqueous layer was concentrated to dryness
4. dissolutionThe resulting product was dissolved in MeOH (10 mL)
5. filtrationfiltered
6. additiontreated with diethyl ether
7. customto precipitate out the salt
8. filtrationThe salt was filtered
9. washwashed with ether
10. customdried in vacuo
11. customto give white solid