Chloroform → 3-Acetoxy-5-t-butyldimethylsiloxycyclopent-1-ene

HRID 2549

Reaktionsgleichung

Reaktionsgleichung von HRID 2549
[Si:1]([O:8][C@@H:9]1[CH2:13][C@H:12]([OH:14])[CH:11]=[CH:10]1)([C:4]([CH3:7])([CH3:6])[CH3:5])([CH3:3])[CH3:2].C(N(CC)CC)C.[C:22](OC=C)(=[O:24])[CH3:23].C(Cl)(Cl)Cl>COC(C)(C)C>[Si:1]([O:8][CH:9]1[CH2:13][CH:12]([O:14][C:22](=[O:24])[CH3:23])[CH:11]=[CH:10]1)([C:4]([CH3:7])([CH3:6])[CH3:5])([CH3:3])[CH3:2]

Komponenten

6

Edukt 4

HCID 6212Chloroform2×HCID 7904Vinyl AcetateHCID 8471TriethylamineHCID 101767472-Cyclopenten-1-ol, 4-[[(1,1-dimethylethyl)dimethylsilyl]oxy]-, cis-2×

Produkt 1

HCID 127633543-Acetoxy-5-t-butyldimethylsiloxycyclopent-1-eneAusbeute 51,1 %

Reagenzien, Katalysatoren, Lösungsmittel 1

HCID 15413tert-Butyl methyl etherLösungsmittel

Versuchsvorschrift

Cis-4-tert-butyldimethylsilyloxy-2-cyclopentenol (10.0 g, 46.6 mmol, prepared in example 3a) is dissolved in tert-butyl methyl ether (60 mL, anhydrous). To the solution is added triethylamine (4.5 mL, 32.3 mmol), pancreatin (30 g, available from Sigma Chemical Company), and vinyl acetate (22 mL, 239 mmol). The reaction is allowed to stir for 7 hours at room temperature. The reaction is then filtered through diatomaceous earth and the filtrate is concentrated under vacuum. The products are separated by chromatography on silica gel (5% to 20% ethyl acetate/hexane) to provide (-)-acetic acid 4-tert-butyldimethylsilyloxy-cyclopent-2-enyl ester (B, 6.1 g, 51% yield, 99% ee), [α]D -0.2°, (c=0.52, chloroform) as a yellow oil and (-)-cis-4-tert-butyldimethylsilyloxy-2-cyclopentenol (A, 4.7 g, 47% yield, >99% ee), [α]D -18.6°, (c=1.01, chloroform) as a yellow oil.

Aufarbeitung

  1. filtrationThe reaction is then filtered through diatomaceous earth
  2. concentrationthe filtrate is concentrated under vacuum
  3. customThe products are separated by chromatography on silica gel (5% to 20% ethyl acetate/hexane)

Quellen und Nachweise

ORD-Eintrag
ord-4080122b276c4fa69f2e3e82eeb5a920
Quelldatensatz
uspto-grants-1998_03
Patentnummer
US05728899

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