Benzene → (-)-(10R)-3,3,8,8,10-Pentamethyl-1,5-dioxaspiro[5,5]undecan-9-one

HRID 440224

Reaktionsgleichung

Reaktionsgleichung von HRID 440224
[CH3:1][C:2]1([CH3:11])[CH2:7][C:6](=[O:8])[CH2:5][C@@H:4]([CH3:9])[C:3]1=[O:10].[CH3:12][C:13]([CH3:18])([CH2:16]O)[CH2:14][OH:15].C1C=CC=CC=1>O>[CH3:12][C:13]1([CH3:18])[CH2:14][O:15][C:6]2([CH2:5][C@@H:4]([CH3:9])[C:3](=[O:10])[C:2]([CH3:1])([CH3:11])[CH2:7]2)[O:8][CH2:16]1

Komponenten

5

Edukt 3

HCID 241BenzeneHCID 31344Neopentyl glycolHCID 10176229Levodione

Produkt 1

HCID 14702805(-)-(10R)-3,3,8,8,10-Pentamethyl-1,5-dioxaspiro[5,5]undecan-9-oneAusbeute 99,2 %

Reagenzien, Katalysatoren, Lösungsmittel 1

HCID 962WaterLösungsmittel

Versuchsvorschrift

A mixture of (-)-(6R)-2,2,6-trimethyl-1,4-cyclohexandione (924 mg, 6.0 mmol), 2,2-dimethyl-1,3-propandiol (791 mg, 7.6 mmol), pyridinium p-tosylate (34 mg, 0.13 mmol), and benzene (15 mL) was heated to reflux under a Dean-Stark water separator for 4 h. The reaction mixture was allowed to cool to room temperature before it was washed with H2O, and dried over anhydrous Na2SO4. Evaporation of solvent gave a pale yellow oil (1.43 g) as the crude product, which was distilled using the Kugel-rohr apparatus (80°-100° C., 0.03 mm Hg) to give pure ketal as a colorless oil (1.31 g, 91%), [a]D -87.7° C. (c 1.10, CH3OH); ir: 1710 cm-1; 1H nmr d: 0.85 (s, 3H, CH3), 0.91 (d, J=6.6 Hz, 3H, CHCH3), 0.97 (s, 6H, 2 CH3), 1.16 (s, 3H, CH3), 1.56 (dd, J=13.5, 13.5 Hz, H-11ax), 1.58 (d, J=14.2 Hz, H-7ax), 2.38 (ddd, J=13.5, 5.3, 3.8 Hz, 1H, H-11eq), 2.47 (dd, J=14.2, 3.8 Hz, 1H, H-7eq), 2.85 (m, 1H, CHCH3), 3.41 and 3.48 (2dd, J=11.4, 1.6 Hz, 2H, 2 equatorial H at C2 and C4), 3.53 and 3.61 (2d, J=11.4 Hz, 2H, 2 axial H at C2 and C4); ms m/e: 240 (M+, 0.58), 141 (27), 155 (98), 83 (27), 69 (100).

Aufarbeitung

  1. temperaturewas heated
  2. washwas washed with H2O
  3. dry with materialdried over anhydrous Na2SO4
  4. customEvaporation of solvent

Quellen und Nachweise

ORD-Eintrag
ord-395accb4eeab49f7ac2765bc38355677
Quelldatensatz
uspto-grants-1996_05
Patentnummer
US05518995

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