Reaktion #57063

Reaktionsgleichung

n-BuLi

Methyl 3-cyclopentylpropanoate

3-cyclopentylpropionic acid

sulfuric acid

dimethyl methylphosphonate

→

product

Ausbeute 82.0%

Dimethyl 4-cyclopentyl-2-oxobutylphosphonate

Ausbeute 82.0%

Lösungsmittel

methanol

THF

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas added dropwise for 10 minutes
2. 2
   workup.STIRRINGThe mixture was stirred for 2 hours at −78° C.
3. 3
   SonstigeThe mixture was quenched with addition of 1N HCl to pH 4-5
4. 4
   SonstigeThe organic layer was separated
5. 5
   Waschenwashed with brine
6. 6
   Trocknendried over MgSO4
7. 7
   SonstigeThe residue was purified through flash chromatography on silica gel (EtOAc:Hexanes=1:1)

Vorschrift

To a solution of dimethyl methylphosphonate (2.17 ml, 20 mmol) in anhydrous THF (20 mL), cooled at −78° C. was added n-BuLi (1.6 M in hexane, 13.7 mL, 22 mmol). The mixture was stirred for 30 minutes at this temperature under nitrogen. Methyl 3-cyclopentylpropanoate (1.56 g, 10 mmol), prepared from 3-cyclopentylpropionic acid (Aldrich) and methanol at the presence of the catalytic amount of the concentrated sulfuric acid (the procedure described in Intermediate 17.1), was added dropwise for 10 minutes. The mixture was stirred for 2 hours at −78° C., gradually was warm to room temperature. The mixture was quenched with addition of 1N HCl to pH 4-5. The organic layer was separated, washed with brine and dried over MgSO4. The residue was purified through flash chromatography on silica gel (EtOAc:Hexanes=1:1) to give the product (1.80 g) with colorless oil in 82% yield. 1HNMR (CD3OD, ppm) δ 1.03 (m, 2H), 1.51 (m, 1H), 1.61 (m, 6H), 1.73 (m, 2H), 2.63 (t, J=7.4 Hz, 2H), 3.09 (d, J=22.7 Hz, 2H), 3.76 (s, 3H), 3.87 (s, 3H)

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