反应详情

A solution of 4-methylbenzaldehyde (0.981 ml, 8.32 mmol), methyl acetoacetate (0.898 ml, 8.32 mmol), piperidine (0.041 ml, 0.416 mmol), and acetic acid (0.024 ml, 0.416 mmol) in benzene (12.5 ml) was refluxed with a Dean Stark apparatus for 1 day. The reaction was concentrated; the residue was dissolved in EtOAc, washed with water, sat. NaHCO3, Brine, dried with Na2SO4, filtered, and concentrated. Purification with column chromatography afforded a 2:3 mixture of E/Z isomers of methyl 2-(4-methylbenzylidene)-3-oxobutanoate (1539.1 mg, 7.05 mmol, 84.7% yield) as yellow oil: E=1H NMR (400 MHz, CHLOROFORM-d) d=7.67 (s, 1 H), 7.29 (d, J=8.2 Hz, 2 H), 7.18 (d, J=8.1 Hz, 2 H), 3.83 (s, 3 H), 2.37 (s, 3 H), 2.36 (s, 3 H) LCMS (m/z) ES+=219 (M+1). Z=1H NMR (400 MHz, CHLOROFORM-d) d=7.55 (s, 1 H), 7.33 (d, J=8.2 Hz, 2 H), 7.20 (d, J=8.1 Hz, 2 H), 3.86 (s, 3 H), 2.42 (s, 3 H), 2.38 (s, 3 H); LCMS (m/z) ES+=219 (M+1).

1. concentrationThe reaction was concentrated
2. dissolutionthe residue was dissolved in EtOAc
3. washwashed with water, sat. NaHCO3, Brine
4. dry with materialdried with Na2SO4
5. filtrationfiltered
6. concentrationconcentrated
7. customPurification with column chromatography
8. customafforded