Oxidative coupling of alkynes mediated by nitroxyl radicals under Sonogashira conditions and Pd-free catalytic approach to stable radicals of 3-imidazoline family with triple bonds
作者:Sergei F. Vasilevsky、Olga L. Krivenko、Igor V. Alabugin
DOI:10.1016/j.tetlet.2007.09.031
日期:2007.11
In the presence of Pd catalyst, 3-imidazoline nitroxyl radicals promote oxidative coupling (dimerization) of terminal alkynes even in the absence of Cu(II) additives. On the other hand, the Pd-free CuI–PPh3–K2CO3–DMF catalytic system leads to the efficient cross-coupling of 1-hydroxy-4-[2-(p-iodophenyl)vinyl]-2,2,5,5-tetramethyl-3-imidazoline-3-oxide with terminal aryl- and hetarylacetylenes with the
在Pd催化剂存在下,即使不存在Cu(II)添加剂,3-咪唑啉硝基氧基也会促进末端炔烃的氧化偶联(二聚)。另一方面,无钯的CuI–PPh 3 –K 2 CO 3 –DMF催化体系导致1-羟基-4- [2-(对-碘苯基)乙烯基] -2,2的有效交叉偶联。,5,5-四甲基-3-咪唑啉-3-氧化物与末端芳基和杂芳基乙炔形成4- [2-(芳基/杂芳基乙炔基)苯基]乙烯基] -2,2,5,5-四甲基-3 -咪唑啉-3-氧化物-1-氧基的产率为70-75%。