Chemical Resources Laboratory, Tokyo Institute of Technology, 4259-R1-5 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
Org Biomol Chem. 2010 Mar 7;8(5):1202-11. doi: 10.1039/b920821f. Epub 2010 Jan 13.
Biginelli reactions were well catalyzed on mesoporous silica MCM-41 (M41) whose activity was much greater than that of amorphous silica. Octane was the most suitable among 6 kinds of solvents examined. The addition of metal ions on M41 enhanced the catalytic activity in the order Al > Ti > Fe = In. Al-planted M41s with Si/Al ratios of 45-35 showed the highest catalytic activity and could be used repeatedly though a small loss of the activity was observed. The catalysis could widely be applied to obtain various substituted dihydropyrimidinones (DHPMs) with high yields, some of which were very difficult to prepare until now. In addition, Biginelli reactions were combined with formyl C-H insertion reactions of diazoester on mesoporous silica; that is, a tandem one-pot four-component DHPM synthesis was attempted. Acetaldehyde, ethyl diazoacetate, p-tolualdehyde, and urea could be condensed and the corresponding DHPM derivative was obtained with 50% yield on Al-planted M41.
Biginelli 反应在中孔硅 MCM-41（M41）上得到了很好的催化，其活性远大于无定形硅。在考察的 6 种溶剂中，辛烷是最合适的。在 M41 上添加金属离子，其催化活性顺序为 Al > Ti > Fe = In。Si/Al 比为 45-35 的 Al 负载的 M41 表现出最高的催化活性，虽然活性略有下降，但可以重复使用。该催化反应可广泛应用于获得各种取代的二氢嘧啶酮（DHPMs），产率很高，其中一些迄今为止很难制备。此外，Biginelli 反应与重氮酯的甲酰基 C-H 插入反应相结合，即在中孔硅上尝试串联一锅四组分 DHPM 合成。可以缩合乙醛、乙基重氮乙酸酯、对甲苯醛和尿素，并在 Al 负载的 M41 上以 50%的产率得到相应的 DHPM 衍生物。
