Lithium Hydroxide → 4-(2-Tert-butoxycarbonyl-ethyl)-3,5-dimethyl-benzoic acid

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Reaktionsgleichung

C[O:2][C:3](=[O:21])[C:4]1[CH:9]=[C:8]([CH3:10])[C:7]([CH2:11][CH2:12][C:13]([O:15][C:16]([CH3:19])([CH3:18])[CH3:17])=[O:14])=[C:6]([CH3:20])[CH:5]=1.[Li+].[OH-]>C(O)C.C(O)(=O)CC(CC(O)=O)(C(O)=O)O>[C:16]([O:15][C:13]([CH2:12][CH2:11][C:7]1[C:8]([CH3:10])=[CH:9][C:4]([C:3]([OH:21])=[O:2])=[CH:5][C:6]=1[CH3:20])=[O:14])([CH3:19])([CH3:18])[CH3:17]

Komponenten

Reaktionsbedingungen

Temperatur: 0 °C

Versuchsvorschrift

To a solution of 4-(2-tert-butoxycarbonyl-ethyl)-3,5-dimethyl-benzoic acid methyl ester (10.8 g, 37.0 mmol) in ethanol (100 mL) a 2 M aq. solution of LiOH (50 mL) is added at 0° C. The turbid mixture is stirred at 0° C. for 30 min, then at rt for 4 h. The mixture is diluted with 10% aq. citric acid solution and extracted three times with diethyl ether. The combined organic extracts are dried over MgSO4, filtered and concentrated. The solid residue is suspended in diethyl ether/heptane, stirred at rt, and filtered. The slurry procedure in diethyl ether/heptane is repeated. The solid material is collected and dried under HV to give 4-(2-tert-butoxycarbonyl-ethyl)-3,5-dimethyl-benzoic acid (5.09 g) as a white crystalline powder; LC-MS: tR=0.95 min, [M+1]+=279.14; 1H NMR (CDCl3): δ 1.47 (s, 9 H), 2.30-2.40 (m, 2 H), 2.39 (s, 6 H), 2.94-3.03 (m, 2 H), 7.75 (s, 2 H).

Aufarbeitung

waitat rt for 4 h
extractionextracted three times with diethyl ether
dry with materialThe combined organic extracts are dried over MgSO4
filtrationfiltered
concentrationconcentrated
stirringstirred at rt
filtrationfiltered
customThe solid material is collected
customdried under HV

Quellen und Nachweise

ORD-Eintrag: ord-003f94326edf4134b5e15827d22d4649
Quelldatensatz: uspto-grants-2011_08
DOI: 10.6084/m9.figshare.5104873.v1
Patentnummer: US08003800B2

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