反応 #2254201

反応方程式

tetrahydro-4H-pyran-4-one

methyl cyanoacetate

ammonium acetate

acetic acid

→

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

溶媒

benzene

water

反応条件

後処理

1. 1
   その他A 50 ml round-bottom flask equipped with a Dean-Stark distillation setup and condenser
2. 2
   その他collected in the Dean-Stark (2 hours)
3. 3
   温度cooled
4. 4
   workup.ADDITIONbenzene (30 ml) added
5. 5
   洗浄the organic layer washed with water (50 ml)
6. 6
   抽出The aqueous layer was extracted with CH2Cl2 (3×50 ml)
7. 7
   洗浄The combined organic phase was washed with sat. NaHCO3 (100 ml), brine (100 ml)
8. 8
   乾燥dried (MgSO4)
9. 9
   ろ過filtered
10. 10
    濃縮concentrated
11. 11
    その他Purified by normal phase SiO2 chromatography (10 to 60% EtOAc/hexanes)

実験手順

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).

出典