반응 #494044

반응 방정식

betulinic acid

potassium carbonate

benzyl bromide

→

(1R,3aS,5aR,5bR,7aR,9S,11aR,11bR, 13aR,13bR)-benzyl 9-hydroxy-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysene-3a-carboxylate

수율 97.0%

용매

DMF

반응 조건

후처리

1. 1
   온도was cooled to rt
2. 2
   기타to precipitate
3. 3
   온도upon cooling
4. 4
   workup.ADDITIONThe mixture was diluted with 200 mL of water
5. 5
   기타the solids that formed
6. 6
   여과were collected by filtration

실험 절차

To a suspension of betulinic acid (12 g, 26.3 mmol) and potassium carbonate (7.26 g, 52.6 mmol) in DMF (150 mL) was added benzyl bromide (3.28 mL, 27.6 mmol). The mixture was heated to 60° C. for 3.5 h, and was cooled to rt. Solids started to precipitate upon cooling. The mixture was diluted with 200 mL of water and the solids that formed were collected by filtration to give (1R,3aS,5aR,5bR,7aR,9S,11aR,11bR, 13aR,13bR)-benzyl 9-hydroxy-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)icosahydro-1H-cyclopenta[a]chrysene-3a-carboxylate (13.92 g, 25.5 mmol, 97% yield) as a white solid. 1H NMR (500 MHz, CHLOROFORM-d) δ ppm 0.74 (s, 3H), 0.75 (s, 3H), 0.79 (s, 3H), 0.82-1.71 (m, 20H), 0.93 (s, 3H), 0.95 (s, 3H), 1.67 (s, 3H), 1.81-1.93 (m, 2H), 2.13-2.21 (m, 1H), 2.27 (ddd, J=12.36, 3.20, 3.05 Hz, 1H), 3.01 (td, J=10.99, 4.88 Hz, 1H), 3.17 (ddd, J=11.44, 5.65, 5.49 Hz, 1H), 4.59 (s, 1H), 4.71 (d, J=1.83 Hz, 1H), 5.06-5.16 (m, 2H), 7.28-7.39 (m, 5H).

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