Practical and diversity-oriented synthesis of multisubstituted benzofurans has been accomplished from simple phenols through a Pummerer annulation/cross-coupling sequence. Operationally simple and rapid reactions of phenols with ketene dithioacetal monoxides (KDMs) with the aid of trifluoroacetic anhydride provide the corresponding 2-methylsulfanylbenzo[b]furans. The scope of the reaction encompasses phenols and KDMs having a broad range of substituents. The remaining methylsulfanyl group in the annulation products is converted to various aryl groups through cross-coupling reactions that we improved specially to this end. This two-step approach to multisubstituted benzofurans is powerful enough to synthesize highly fluorescent benzofuran derivatives as well as the naturally occurring Eupomatenoid family.
已成功实现从简单
酚类化合物合成多取代
苯并呋喃的实用且多样化的合成方法,采用了Pummerer环化/交叉偶联序列。
酚类与
酮硫酰单
氧化物(K
DMs)在
三氟乙酸酐的帮助下发生操作简便、迅速的反应,生成相应的
2-甲基硫苯并[b]
呋喃。该反应的适用范围涵盖了具有广泛取代基的
酚类和K
DMs。环化产物中的剩余
甲基硫基团通过我们特别改进的交叉偶联反应转化为各种芳基。此两步法合成多取代
苯并呋喃的能力足以合成高度荧光的
苯并呋喃衍
生物,以及
天然存在的Eupomatenoid家族。