反应详情

The acetate 4 (1.3 g 3.02 mmol) was dissolved in methanol (20 mL) under an inert Ar atmosphere, and the resulting solution treated with 10% methanolic KOH (8 mL). The mixture was stirred at room temperature for 1.5 h, and then concentrated under reduced pressure at approx. 40° C. to a volume of 10 mL. This solution was poured into ice water (300 mL), and the resulting white precipitate was filtered, washed with water and dried. Crystallization from EtOAc/MeOH gave 5 (1.10 g, 94%), mp 189-190° C.; IR(CHCl3) 2934, 2339, 1609, 1490, 1453, 1291, 1040, 837, 808, 705, 663, 608, 578, 550, 517 cm−1; 1H NMR (300 MHz, CDCl3) δ 1.02 (s, 3H, 18-CH3), 1.07 (s, 3H, 19-CH3), 3.55 (m, 1H, 3α-H), 5.41 (br s, 1H, 6-H), 5.99 (s, 1H, 16-H), 7.30 (m, 2H, aromatic-Hs), 7.54 (s, 1H, aromatic-H), 7.80 (s, 1H, aromatic-H), and 7.96 (s, 1H, 21-H). HRMS calcd 411.2407 (C26H32ON2.Na+). found 411.2396.

1. concentrationconcentrated under reduced pressure at approx. 40° C. to a volume of 10 mL
2. additionThis solution was poured into ice water (300 mL)
3. filtrationthe resulting white precipitate was filtered
4. washwashed with water
5. customdried
6. customCrystallization from EtOAc/MeOH