反応 #2254221

反応方程式

6-oxaspiro[4.5]decan-9-one

methylcyanoacetate

ammonium acetate

acetic acid

→

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

収率 87.8%

溶媒

hexane

benzene

EtOAc

benzene

反応条件

後処理

1. 1
   温度was heated
2. 2
   温度at reflux in a 250 ml round bottom flask
3. 3
   その他equipped with a Dean-Stark and a reflux condenser
4. 4
   温度After cooling
5. 5
   その他the layer was separated
6. 6
   洗浄the organic was washed by water (120 ml)
7. 7
   抽出the aqueous layer was extracted by CH2Cl2 (3×120 ml)
8. 8
   洗浄The combined organic was washed with sat'd NaHCO3, brine
9. 9
   その他dried
10. 10
    濃縮concentrated
11. 11
    その他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)
12. 12
    その他gave
13. 13
    workup.ADDITIONa mixture of E and Z isomers

実験手順

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.

出典