HCID 10030981, Verbindung → HCID 10460748, Verbindung
Reaktionsgleichung
[Si:1]([O:8][CH2:9][CH2:10][CH2:11][C@H:12]([C@@H:14]1[C@:31]2([CH3:32])[C@H:17]([C@H:18]3[C@H:28]([CH2:29][CH2:30]2)[C@:26]2([CH3:27])[C:21]([CH2:22][C@@H:23]([O:33][CH:34]4[CH2:39][CH2:38][CH2:37][CH2:36][O:35]4)[CH2:24][CH2:25]2)=[CH:20][C:19]3=[O:40])[CH2:16][CH2:15]1)[CH3:13])([C:4]([CH3:7])([CH3:6])[CH3:5])([CH3:3])[CH3:2]>CCOC(C)=O.[Pt](=O)=O>[Si:1]([O:8][CH2:9][CH2:10][CH2:11][C@H:12]([C@@H:14]1[C@:31]2([CH3:32])[C@H:17]([C@H:18]3[C@H:28]([CH2:29][CH2:30]2)[C@:26]2([CH3:27])[C@H:21]([CH2:22][C@@H:23]([O:33][CH:34]4[CH2:39][CH2:38][CH2:37][CH2:36][O:35]4)[CH2:24][CH2:25]2)[CH2:20][C:19]3=[O:40])[CH2:16][CH2:15]1)[CH3:13])([C:4]([CH3:5])([CH3:6])[CH3:7])([CH3:3])[CH3:2]Komponenten
4
Edukt 1
Produkt 1
Reagenzien, Katalysatoren, Lösungsmittel 2
Versuchsvorschrift
Compound 2004 (1.0 g, 1.75 mmol) was dissolved in EtOAc (75 ml) and platinum(IV) oxide (0.012 g, 0.049 mmol) was added. The mixture was placed on a hydrogenation apparatus (atmospheric). The set-up was evacuated to remove the dissolved oxygen and then hydrogen was introduced. The evacuation and introduction of hydrogen process was repeated 2 times. The reaction was stirred under hydrogen at atmospheric pressure for 2.5 hours. The reaction mixture was filtered through Celite and concentrated in vacuo. The crude product was purified by flash chromatography (SiO2, hexanes:EtOAc gradient starting with 20:1) giving compound 2005 as a white solid (0.70 g, 71%). 24-t-Butyldimethylsilyloxy-3β-tetrahydropyranyloxy-5α-chelan-7β-ol was obtained as a by-product (21%). (Note: This by-product could be converted to the desired ketone 2005 with Collin's reagent in 64% yield.) Compound 2005: 1H NMR (500 MHz, CDCl3) δ: 4.73-4.66 (m, 1H, THP methine H), 3.95-3.85 (m, 1H, THP CH2O), 3.66-3.52 (m, 3H, THP CH2O & C-24 H), 3.50-3.45 (M, 1H, C-3 H), 1.08 (s, 3H, C-19 H), 0.91 (d, J=6.6 Hz, C-21 H), 0.89 (s, 9H, t-Bu), 0.64 (s, 3H, C-18 H), 0.04 (s, 6H, TBDMS CH3); IR (CHCl3) 2900, 1685 cm-1 ; MS (CI/isobutane) m/z 575 (M+1, 85%), 491 (M+1-THP, 100%); m.p. 166-170° C.; Anal. calcd. for C35H62O4Si: C=73.12, H=10.87; Found: C=72.88, H=10.78.