Reaktion #2254221

Reaktionsgleichung

6-oxaspiro[4.5]decan-9-one

methylcyanoacetate

ammonium acetate

acetic acid

→

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

Ausbeute 87.8%

Lösungsmittel

hexane

benzene

EtOAc

benzene

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturwas heated
2. 2
   Temperaturat reflux in a 250 ml round bottom flask
3. 3
   Sonstigeequipped with a Dean-Stark and a reflux condenser
4. 4
   TemperaturAfter cooling
5. 5
   Sonstigethe layer was separated
6. 6
   Waschenthe organic was washed by water (120 ml)
7. 7
   Extraktionthe aqueous layer was extracted by CH2Cl2 (3×120 ml)
8. 8
   WaschenThe combined organic was washed with sat'd NaHCO3, brine
9. 9
   Sonstigedried
10. 10
    Einengenconcentrated
11. 11
    Sonstigethe 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
    Sonstigegave
13. 13
    workup.ADDITIONa mixture of E and Z isomers

Vorschrift

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.

Quelle