The selective preparation of monoketals 3a-f from pentaerythritol 1 and cyclic, acyclic, aromatic, and aliphatic ketones 2a-f was achieved by a facile method. The extreme polarity and low solubility of pentaerythritol in almost all organic solvents were the main difficulties to be overcome for the preparation of monoketals in good yields and high selectivity. A benzene-dimethylformamide (40:60) mixture proved to be excellent for the ketalization. The one-step procedure developed allowed the preparation of monoketals in good yields and good to excellent selectivity (higher than 90%).
通过一种简便的方法成功地从五羟基醇1和环状、非环状、芳香族和
脂肪族
酮2a-f选择性制备了单
酮基化合物3a-f。五羟基醇在几乎所有有机溶剂中的极高极性和低溶解度是制备单
酮基化合物时主要需要克服的困难。实验表明,
苯-二
甲基甲
酰胺(40:60)混合物在
酮基化反应中表现优异。所开发的一步法程序使得单
酮基化合物的制备在良好收率和良好至优异选择性(超过90%)下得以实现。