反应详情

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).

1. customA 50 ml round-bottom flask equipped with a Dean-Stark distillation setup and condenser
2. customcollected in the Dean-Stark (2 hours)
3. temperaturecooled
4. additionbenzene (30 ml) added
5. washthe organic layer washed with water (50 ml)
6. extractionThe aqueous layer was extracted with CH2Cl2 (3×50 ml)
7. washThe combined organic phase was washed with sat. NaHCO3 (100 ml), brine (100 ml)
8. dry with materialdried (MgSO4)
9. filtrationfiltered
10. concentrationconcentrated
11. customPurified by normal phase SiO2 chromatography (10 to 60% EtOAc/hexanes)