反应详情

A solution of 2,2-dimethyl-pent-4-enal (5.0 g, 44 mmol), cyano-acetic acid ethyl ester (5.12 mL, 48 mmol), piperidine (1.3 mL, 14 mmol) and acetic acid (4.52 mL, 80 mmol) in 170 mL of toluene was heated under reflux for 18 hours in a flask equipped with a Dean-Stark separator. Several mL of water was collected in the trap. The reaction was cooled and washed with 1N HCl, NaHCO3 and brine, successively. The organic layers were dried over Na2SO4 and concentrated to an oil. This oil was chromatographed eluting with 20% of EtOAc in hexane to give a combination of two lots total 8.3 g (91%). 1H NMR (400 MHz; CDCl3) 1.28 (s, 6H), 1.32 (t, 3H, J=7 Hz),. 2.26 (d, 2H, J=7.6 Hz), 4.27 (q, 2H, J=7.2 Hz), 5.08 (d, 1H, J=12 Hz), 5.10 (d, 1H, J=4 Hz), 5.72 (m, 1H).

1. temperatureunder reflux for 18 hours in a flask
2. customequipped with a Dean-Stark separator
3. customSeveral mL of water was collected in the trap
4. temperatureThe reaction was cooled
5. washwashed with 1N HCl, NaHCO3 and brine
6. dry with materialThe organic layers were dried over Na2SO4
7. concentrationconcentrated to an oil
8. customThis oil was chromatographed
9. washeluting with 20% of EtOAc in hexane
10. customto give a combination of two lots total 8.3 g (91%)