Reacción #2254201

Ecuación de reacción

tetrahydro-4H-pyran-4-one

methyl cyanoacetate

ammonium acetate

acetic acid

→

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

Disolventes

benzene

water

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroA 50 ml round-bottom flask equipped with a Dean-Stark distillation setup and condenser
2. 2
   Otrocollected in the Dean-Stark (2 hours)
3. 3
   Temperaturacooled
4. 4
   workup.ADDITIONbenzene (30 ml) added
5. 5
   Lavadothe organic layer washed with water (50 ml)
6. 6
   ExtracciónThe aqueous layer was extracted with CH2Cl2 (3×50 ml)
7. 7
   LavadoThe combined organic phase was washed with sat. NaHCO3 (100 ml), brine (100 ml)
8. 8
   Secadodried (MgSO4)
9. 9
   Filtraciónfiltered
10. 10
    Concentraciónconcentrated
11. 11
    OtroPurified by normal phase SiO2 chromatography (10 to 60% EtOAc/hexanes)

Procedimiento

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).

Fuente