摘要
A regioselective synthesis of 6-alkyl- and 6-aryluracils was developed by the dimerization of 3-alkyl- and 3-aryl-2-propynamides promoted by either Cs2CO3 or K3PO4. A range of 3-aryl-2-propynamides, with both electron-deficient and electron-rich 3-aryl substituents, were successfully reacted in high yields. Cs+ acts as a soft Lewis acid to polarize the carbon-carbon triple bond, and solid K3PO4 interacts with carbonyl oxygen, promoting intermolecular nucleophilic attack by the only weakly nucleophilic amide nitrogen. Experiments were conducted to support the proposed mechanism.
- 出版日期2017-6-2