Reaktion #221027

Reaktionsgleichung

1,3-dimethyl-3,4,5,6-tetrahydro-2(1 H)-pyrimidinone

Allyl iodide

3,3-dimethyl-3-phenyl propionic acid

dry ice acetone

Lithium diisopropylamide

→

oil

Ausbeute 64.0%

2-allyl-3-methyl-3-phenylbutanoic acid

Ausbeute 64.0%

Lösungsmittel

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.STIRRINGto stir for 30 minutes
2. 2
   workup.STIRRINGto stir overnight
3. 3
   Temperaturwhile warming to room temperature
4. 4
   SonstigeThe reaction is quenched by the addition of 10% aqueous hydrochloric acid solution
5. 5
   Extraktionextracted thrice with ethyl acetate
6. 6
   WaschenThe combined extracts are washed twice with 10% aqueous hydrochloric acid solution and once with saturated sodium chloride solution
7. 7
   Trocknendried over anhydrous sodium sulfite
8. 8
   Einengenconcentrated under reduced pressure

Vorschrift

In accordance with a modified literature procedure (Pfeffer, P. E.; Silbert, L. S.; Chirinko, J. M. J. Org. Chem. 37(3), 1972, 451-458), a solution of 3,3-dimethyl-3-phenyl propionic acid (0.50 g, 2.8 mmol, from Reference Example 22) in tetrahydrofuran (5 mL) is cooled to −40° C. (dry ice/acetone) while stirring under a nitrogen atmosphere. Lithium diisopropylamide (Aldrich, 2.0 M solution in tetrahydrofuran/ethylbenzene/heptane, 3.1 mL, 6.2 mmol) is added dropwise via syringe, followed by 1,3-dimethyl-3,4,5,6-tetrahydro-2(1 H)-pyrimidinone (DMPU, 0.37 mL, 4.2 mmol). The reaction mixture is then allowed to warm to room temperature and to stir for 30 minutes before being re-cooled to 0° C. (ice water bath). Allyl iodide (0.15 mL, 1.3 mmol) is then added neat via syringe and the reaction mixture is allowed to stir overnight while warming to room temperature. The reaction is quenched by the addition of 10% aqueous hydrochloric acid solution and extracted thrice with ethyl acetate. The combined extracts are washed twice with 10% aqueous hydrochloric acid solution and once with saturated sodium chloride solution, dried over anhydrous sodium sulfite, and concentrated under reduced pressure. Flash chromatography (silica gel, hexane/dichloromethane/ethyl acetate) is performed to give a clear blond oil (0.39 g, 64%). MS (ES−): (M−H)=217.0

Quelle