Bismuth triflate-catalyzed rearrangement of acetates of the Baylis–Hillman adducts into (E)-trisubstituted alkenes
- 作者：Thierry Ollevier ; Topwe M. Mwene-Mbeja
- 关键词：Bismuth ; Lewis acids ; Rearrangement ; Claisen ; Morita– ; Baylis– ; Hillman ; Green chemistry
- 刊名：Tetrahedron
- 出版年：2008
- 期刊代码：107_00404020
- 类别：ch
- 出版时间：26 May 2008
- 卷：64
- 期：22
- 页码：5150-5155
- 文件大小：735 K
摘要
In the presence of a catalytic amount of bismuth triflate, methyl 3-acetoxy-3-aryl-2-methylenepropanoates and 3-acetoxy-3-aryl-2-methylenepropanitriles were smoothly converted into methyl (2E)-2-(acetoxymethyl)-3-arylprop-2-enoates and (2E)-2-(acetoxymethyl)-3-arylprop-2-enenitriles, respectively. A remarkable reversal in stereochemical directions from ester to nitrile was observed. 3-Aryl-3-hydroxy-2-methylenepropanoates and 3-aryl-3-hydroxy-2-methylenepropanitriles could be easily obtained as Baylis–Hillman adducts from methyl acrylate and acrylonitrile, respectively. The overall process is an efficient isomerization of the Baylis–Hillman adducts to the corresponding cinnamyl derivatives. The isomerization reaction proceeded rapidly and afforded smoothly the cinnamyl acetates in moderate to very good yields using catalytic amounts of Bi(OTf)3·4H2O (10 mol%).