Réaction #2254201

Équation de réaction

tetrahydro-4H-pyran-4-one

methyl cyanoacetate

ammonium acetate

acetic acid

→

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

Solvants

benzene

water

Conditions de réaction

Traitement

1. 1
   AutreA 50 ml round-bottom flask equipped with a Dean-Stark distillation setup and condenser
2. 2
   Autrecollected in the Dean-Stark (2 hours)
3. 3
   Températurecooled
4. 4
   workup.ADDITIONbenzene (30 ml) added
5. 5
   Lavagethe organic layer washed with water (50 ml)
6. 6
   ExtractionThe aqueous layer was extracted with CH2Cl2 (3×50 ml)
7. 7
   LavageThe combined organic phase was washed with sat. NaHCO3 (100 ml), brine (100 ml)
8. 8
   Séchagedried (MgSO4)
9. 9
   Filtrationfiltered
10. 10
    Concentrationconcentrated
11. 11
    AutrePurified by normal phase SiO2 chromatography (10 to 60% EtOAc/hexanes)

Mode opératoire

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).

Source