Reacción #2254221

Ecuación de reacción

6-oxaspiro[4.5]decan-9-one

methylcyanoacetate

ammonium acetate

acetic acid

→

methyl 2-cyano-2-[6-oxaspiro[4.5]decan-9-ylidene]acetate

Rendimiento 87.8%

Disolventes

hexane

benzene

EtOAc

benzene

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturawas heated
2. 2
   Temperaturaat reflux in a 250 ml round bottom flask
3. 3
   Otroequipped with a Dean-Stark and a reflux condenser
4. 4
   TemperaturaAfter cooling
5. 5
   Otrothe layer was separated
6. 6
   Lavadothe organic was washed by water (120 ml)
7. 7
   Extracciónthe aqueous layer was extracted by CH2Cl2 (3×120 ml)
8. 8
   LavadoThe combined organic was washed with sat'd NaHCO3, brine
9. 9
   Otrodried
10. 10
    Concentraciónconcentrated
11. 11
    Otrothe residual was purified by flash chromatography (340 g silica gel column, eluted by EtOAc in hexane: 5% EtOAc, 2 CV; 5-25%, 14 CV; 25-40%, 8 CV)
12. 12
    Otrogave
13. 13
    workup.ADDITIONa mixture of E and Z isomers

Procedimiento

A mixture of 6-oxaspiro[4.5]decan-9-one (13.74 g, 89.1 mmol), methylcyanoacetate (9.4 ml, 106.9 mmol), ammonium acetate (1.79 g, 26.17 mmol) and acetic acid (1.02 ml, 17.8 mmol) in benzene (75 ml) was heated at reflux in a 250 ml round bottom flask equipped with a Dean-Stark and a reflux condenser. After 3 h, TLC (25% EtOAc in hexane, PMA stain) showed the reaction was completed. After cooling, benzene (50 ml) was added and the layer was separated, the organic was washed by water (120 ml) and the aqueous layer was extracted by CH2Cl2 (3×120 ml). The combined organic was washed with sat'd NaHCO3, brine, dried and concentrated and the residual was purified by flash chromatography (340 g silica gel column, eluted by EtOAc in hexane: 5% EtOAc, 2 CV; 5-25%, 14 CV; 25-40%, 8 CV) gave a mixture of E and Z isomers: methyl 2-cyano-2-[6-oxaspiro[4.5]decan-9-ylidene]acetate (18.37 g, 87.8% yield, m/z 236.0 [M+H]+ observed) as a clear oil.

Fuente