反应详情

To a solution of methyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-(hydroxymethyl)-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-9-yl)benzoate (1 g, 1.789 mmol) in CH2Cl2 (70 ml) was added PCC (1.157 g, 5.37 mmol). The resulting dark brown mixture was stirred at rt for 4 h. TLC analysis showed the reaction was complete. The mixture was filtered through a short bed of Celite and silica gel, washed with excess of CH2Cl2. The filtrate was concentrated in vacuo. The crude mixture was purified by Biotage on normal phase silica gel. The fractions containing the expected product were combined and concentrated in vacuo to afford methyl 4-((1R,3aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-formyl-5a,5b,8,8,11a-pentamethyl-1-(prop-1-en-2-yl)-2,3,3a,4,5,5a,5b,6,7,7a,8,11,11a,11b,12,13,13a,13b-octadecahydro-1H-cyclopenta[a]chrysen-9-yl)benzoate as a solid (0.8 g). LCMS: m/e 557.2 (MH+), 3.67 min (method 2).

1. filtrationThe mixture was filtered through a short bed of Celite and silica gel
2. washwashed with excess of CH2Cl2
3. concentrationThe filtrate was concentrated in vacuo
4. customThe crude mixture was purified by Biotage on normal phase silica gel
5. additionThe fractions containing the expected product
6. concentrationconcentrated in vacuo