Palladium-Catalyzed Tandem Reaction of Yne-Propargylic Carbonates with Boronic Acids: A Simple Method for the Synthesis of Fused Aromatic Rings through Allene-Mediated Electrocyclization
作者:Feng Wang、Xiaofeng Tong、Jiang Cheng、Zhaoguo Zhang
DOI:10.1002/chem.200400573
日期:2004.11.5
The palladium-catalyzed tandem reactions of yne-propargylic carbonates with aryl boronic acids, 2-furyl boronic acid, and 2-thiopheneboronic acid, followed by 6pi-electrocyclization to give fused ring aromatic products such as naphthalene, benzofuran, and benzothiophene derivatives are realized. Screening of the reaction conditions revealed that the combination of [Pd(PPh3)4] in THF gave the best results
炔丙基碳酸酯与芳基硼酸,2-呋喃基硼酸和2-噻吩基硼酸进行钯催化的串联反应,然后进行6π电环化,生成稠环芳族产物,如萘,苯并呋喃和苯并噻吩衍生物。 。反应条件的筛选表明,在炔丙基碳酸酯与苯基硼酸反应中,[Pd(PPh3)4]在THF中的组合在反应性和产物收率方面提供了最佳结果。当使用取代的苯基硼酸时,该反应对位阻敏感。但是,当我们将2-呋喃基硼酸用作有机金属试剂时,大多数底物的性能都非常好,可以得到苯并呋喃衍生物。此外,2-噻吩硼酸也是一种非常有效的偶合试剂,可以高收率获得苯并噻吩。提出了一种机制,该机制涉及由Pd0和碳酸炔丙基酯形成烯丙基钯络合物,然后插入分子内三键和Suzuki偶联反应,然后进行电环化。