Reaktion #349965

Reaktionsgleichung

methyl phenylacetate

phosphonate

n-butyllithium

dimethyl methylphosphonate

→

dimethyl 2-oxo-3-phenylpropylphosphonate

Ausbeute 29.0%

Lösungsmittel

acetic acid

hexane

tetrahydrofuran

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe reaction temperature less than -70° (20 minutes)
2. 2
   workup.WAITAfter 3.5 hours at -78° the reaction mixture was allowed
3. 3
   Sonstigerotary evaporated to a white gel
4. 4
   Extraktionthe aqueous phase extracted with 100 ml portions of chloroform (3x)
5. 5
   Trocknendried (MgSO4)
6. 6
   Einengenconcentrated (water aspirator) to a crude residue
7. 7
   workup.DISTILLATIONdistilled

Vorschrift

A solution of 6.2 g (50 mmoles) dimethyl methylphosphonate (Aldrich) in 125 ml dry tetrahydrofuran was cooled to -78° in a dry nitrogen atmosphere. To the stirred phosphonate solution was added 21 ml of 2.37 M n-butyllithium in hexane solution (Alfa Inorganics, Inc.) dropwise over a period of 18 minutes at such a rate that the reaction temperature never rose above -65°. After an additional 5 minutes stirring at -78°, 7.5 g (50.0 mmole) methyl phenylacetate was added dropwise at a rate that kept the reaction temperature less than -70° (20 minutes). After 3.5 hours at -78° the reaction mixture was allowed to warm to ambient temperature, neutralized with 6 ml acetic acid and rotary evaporated to a white gel. The gelatonous material was taken up in 75 ml water, the aqueous phase extracted with 100 ml portions of chloroform (3x), the combined organic extracts were backwashed (50 cc H2O), dried (MgSO4), and concentrated (water aspirator) to a crude residue and distilled, b.p. 134°-5° (<0.1 mm) to give 3.5 g (29%) dimethyl 2-oxo-3-phenylpropylphosphonate. (2).

Quelle