反应详情

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.

1. temperaturewas heated
2. temperatureat reflux in a 250 ml round bottom flask
3. customequipped with a Dean-Stark and a reflux condenser
4. temperatureAfter cooling
5. customthe layer was separated
6. washthe organic was washed by water (120 ml)
7. extractionthe aqueous layer was extracted by CH2Cl2 (3×120 ml)
8. washThe combined organic was washed with sat'd NaHCO3, brine
9. customdried
10. concentrationconcentrated
11. customthe 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. customgave
13. additiona mixture of E and Z isomers