反应详情

温度

60 °C

To a rbf containing a solution of diisopropyl 6-((1R,3 aS,5aR,5bR,7aR,11aS,11bR,13aR,13bR)-3a-((benzyloxy)carbonyl)-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)spiro[3.3]hept-5-ene-2,2-dicarboxylate (0.053 g, 0.047 mmol (based on 70% purity)) in DCE (2 mL) was added triethylamine (10.43 μl, 0.075 mmol), t-butyldimethylsilane (0.016 mL, 0.094 mmol), and palladium(II) acetate (2.63 mg, 0.012 mmol). The mixture was flushed with nitrogen, then was heated to 60° C. for 4.5 h. An additional 3 mg of palladium (II) acetate were added along with 16 μL of t-butyldimethylsilane. The mixture was flushed with nitrogen, then was heated to 60° C. for an additional 2.5 h. The mixture was cooled to rt and was filtered through a plug of celite and sicla gel which was then washed with 25% EtOAc in hexanes. The filtrate was concentrated under reduced pressure to give diisopropyl 6-((1R,3 aS,5aR,5bR,7aR,11aS,11bR,13 aR,13bR)-3a-(((tert-butyldimethylsilyl)oxy)carbonyl)-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)spiro[3.3]hept-5-ene-2,2-dicarboxylate (0.026 g, 0.021 mmol (based on 65% purity), 44.2% yield) as a clear, colorless foam. 1H NMR (500 MHz, chloroform-d) δ=5.86 (s, 1H), 5.51 (dd, J=6.3, 1.7 Hz, 1H), 5.13-5.01 (m, 2H), 4.73 (s, 1H), 4.60 (s, 1H), 3.06 (td, J=10.8, 4.1 Hz, 1H), 2.73-2.66 (m, 4H), 2.62-2.55 (m, 2H), 1.69 (s, 3H), 0.96 (s, 9H), 2.54-0.76 (m, 49H), 0.30-0.28 (m, 6H). The material was used in the next step with no additional purification.

1. customThe mixture was flushed with nitrogen
2. additionAn additional 3 mg of palladium (II) acetate were added along with 16 μL of t-butyldimethylsilane
3. customThe mixture was flushed with nitrogen
4. temperaturewas heated to 60° C. for an additional 2.5 h
5. temperatureThe mixture was cooled to rt
6. filtrationwas filtered through a plug of celite
7. washsicla gel which was then washed with 25% EtOAc in hexanes
8. concentrationThe filtrate was concentrated under reduced pressure