反应详情

Paraformaldehyde (6.32 g) was added portionwise to a solution of 211 (2.21 g, 7.04 mmol) in toluene (55 ml) with pTSA (60 mg). The reaction mixture was heated under reflux for 2 h. Further paraformaldehyde (632 mg) was added and heating under reflux was continued overnight. Additional pTSA (60 mg) and paraformaldehyde (1.9 g) was added to the reaction mixture portionwise over 2 h. The solution was cooled to rt, water (50 ml) and ethyl acetate (60 ml) were added. The layers were separated and the organic layer was washed with water (2×50 ml) and brine (50 ml), dried (MgSO4) and concentrated in vacuo to afford the title compound (2.15 g, 94%) as a colourless oil. 1H NMR indicated a mixture of conformers, signals for both conformers are listed 1.04, 1.12 (3H, d, J=6.7 Hz, CH3CH), 2.14, 2.17 (3H, s, CH3CO), 2.38-2.51 (1H, m, CHH for both conformers), 2.89-3.06 (1H, m, CHH for both conformers), 3.84, 3.85 (3H, s, OCH3), 4.06-4.6 (2H, m, CH2 for both conformers), 5.01-5.02 (3H, m, CHCH3 and CH2Ph for both conformers), 6.6-6.64 (2H, m, 2×CH for both conformers), 7.28-7.44 (5H, m, 5×CH, phenyl for both conformers). LC/MS (ES+) tr=1.02 min, m/z 348.19 (M++Na).

1. temperatureThe reaction mixture was heated
2. temperatureunder reflux for 2 h
3. temperatureheating
4. temperatureunder reflux
5. customThe layers were separated
6. washthe organic layer was washed with water (2×50 ml) and brine (50 ml)
7. dry with materialdried (MgSO4)
8. concentrationconcentrated in vacuo