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 nitroxylradicals 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