Unusual aluminum chloride-assisted conversion of isopropenyl acetate into 3-acetyl- and 3,5-diacetyl-2,6-dimethyl- 4H-pyran-4-ones
作者:V. L. Novikov、O. P. Shestak、V. A. Denisenko
DOI:10.1007/s11172-010-0283-0
日期:2010.8
Reflux of isopropenyl acetate with an excess of AlCl3 in 1,2-dichloroethane affords 3,5-diacetyl-2,6-dimethyl-4H-pyran-4-one in 17% yield. The mild acidic cleavage of the latter (2% HCl, 20 °C, 16 h) gives 3-acetyl-2,6-dimethyl-4H-pyran-4-one in 87% yield, whereas this reaction under more drastic conditions (17% HCl, reflux, 3 h) gives 2,6-dimethyl-4H-pyran-4-one in 61% yield.
乙酸异丙烯酯与过量的 AlCl3 在 1,2-二氯乙烷中回流,得到 3,5-二乙酰-2,6-二甲基-4H-吡喃-4-酮,产率为 17%。后者的温和酸性裂解(2% HCl,20 °C,16 小时)以 87% 的产率得到 3-乙酰基-2,6-二甲基-4H-吡喃-4-one,而该反应在更剧烈的条件下( 17% HCl,回流,3 小时)以 61% 的产率得到 2,6-二甲基-4H-吡喃-4-酮。