Modular Synthesis of Phenanthro[9,10-<i>c</i>]thiophenes by a Sequence of CH Activation, Suzuki Cross-Coupling and Photocyclization Reactions
作者:Ingo Schnapperelle、Thorsten Bach
DOI:10.1002/chem.201402765
日期:2014.7.28
ortho‐position of one of the aryl substituents. One aryl group was introduced by an oxidative cross‐coupling reaction, involving a CH activation at C4(3) of the thiophene core. The other aryl group was in most cases introduced by a Suzuki cross‐coupling reaction, which succeeded the oxidative cross‐coupling step. Photocyclization reactions of the 3,4‐diarylthiophenes were performed in a solvent mixture
总共合成了15个不同的3,4-二芳基噻吩,它们在一个芳基取代基的邻位带有一个氯原子。通过氧化交叉偶联反应引入一个芳基,该反应涉及噻吩核的C4(3)处的CH活化。在大多数情况下,另一个芳基是通过铃木交叉偶联反应引入的,该反应是氧化交叉偶联步骤的后续步骤。3,4-二芳基噻吩的光环化反应是在苯和乙腈的混合溶剂中(50:50 v / v)在λ = 254 nm处进行的,标题化合物的收率为60-82%。在邻位确定光环化的选择性氯取代的芳基环由氯取代基的位置决定。在另一个环上,观察到一个单一的区域异构体的苯基和对位取代的苯基。对于2-萘基和邻位取代的苯环,人们明显倾向于主要的区域异构体,而苯环中的间位取代则导致5和7位取代的菲咯啉的比例约为1:1 [9,10] [ c ]噻吩。从机理上讲,光环化很可能发生在光化学允许的,旋转的[(4n + 2)π]过程中,并伴随着HCl的消除。显示了两个菲咯啉[9,10-