Reaktion #2254201

Reaktionsgleichung

tetrahydro-4H-pyran-4-one

methyl cyanoacetate

ammonium acetate

acetic acid

→

methyl 2-cyano-2-(oxan-4-ylidene)acetate

Lösungsmittel

benzene

water

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeA 50 ml round-bottom flask equipped with a Dean-Stark distillation setup and condenser
2. 2
   Sonstigecollected in the Dean-Stark (2 hours)
3. 3
   Temperaturcooled
4. 4
   workup.ADDITIONbenzene (30 ml) added
5. 5
   Waschenthe organic layer washed with water (50 ml)
6. 6
   ExtraktionThe aqueous layer was extracted with CH2Cl2 (3×50 ml)
7. 7
   WaschenThe combined organic phase was washed with sat. NaHCO3 (100 ml), brine (100 ml)
8. 8
   Trocknendried (MgSO4)
9. 9
   Filtrationfiltered
10. 10
    Einengenconcentrated
11. 11
    SonstigePurified by normal phase SiO2 chromatography (10 to 60% EtOAc/hexanes)

Vorschrift

A 50 ml round-bottom flask equipped with a Dean-Stark distillation setup and condenser was charged with tetrahydro-4H-pyran-4-one (4.61 ml, 50 mmol), methyl cyanoacetate (5.3 ml, 60 mmol), ammonium acetate (1 g, 13 mmol), acetic acid (0.57 ml, 10 mmol) and benzene (30 ml). The mixture was refluxed until no more water collected in the Dean-Stark (2 hours), cooled, benzene (30 ml) added and the organic layer washed with water (50 ml). The aqueous layer was extracted with CH2Cl2 (3×50 ml). The combined organic phase was washed with sat. NaHCO3 (100 ml), brine (100 ml) dried (MgSO4), filtered and concentrated. Purified by normal phase SiO2 chromatography (10 to 60% EtOAc/hexanes) to afford methyl 2-cyano-2-(oxan-4-ylidene)acetate as a colorless oil (6.30 g, 70%, m/z: 181.1 [M+H]+ observed).

Quelle