Synthetic and mechanistic aspects of cross-coupling of nitroxyl radicals of 3-imidazoline series with terminal alkynes
作者:Sergei F. Vasilevsky、Olga L. Krivenko、Vitalii R. Gorelik、Igor V. Alabugin
DOI:10.1016/j.tet.2008.06.088
日期:2008.9
Practical syntheticapproaches to the new class of acetylenic derivatives of 3-imidazolyl-3-oxide-1-oxyls, including biradicals, were developed through cross-coupling reactions of 3-imidazolyl halides with either terminal alkynes or their copper salts. The presence of nitroxyl functional group as an internal oxidant leads to a competition between the formation of cross-coupling products and the products
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