Sterically crowded five-membered heterocyclic systems. Part 3. Unexpected formation of stable flexible pyrrolidinoxyl biradicals via nitrone aldol dimers: a spectroscopic and mechanistic study
作者:Ryszard B. Nazarski、Romuald Skowroński
DOI:10.1039/p19890001603
日期:——
substituted cyclic nitrones (1) and subsequent aerial oxidation gave new pyrrolidinoxyl radicals (4) and the corresponding crystalline biradical species, to which the structure (5) was assigned unequivocally from spectroscopic (e.s.r., u.v.-visible, mass, and 1H and 13C n.m.r. spectra) and mechanistic considerations. Base-catalysed self-condensation of the nitrones (1), to give the nitrone hydroxylamines
将甲基碘化镁添加到各种取代的环硝酮中(1),随后进行空气氧化,得到新的吡咯烷基氧基(4)和相应的结晶双自由基物质,其结构(5)明确地由光谱确定(esr,uv-可见,质量) ,以及1 H和13 C nmr光谱)和机理方面的考虑。碱催化的硝酮自缩合(1),得到硝酮羟胺(18),然后进行格氏试剂加成,得到拥挤的双-N-羟基化合物(3);然后将它们氧化成双自由基(5)。的双自由基(两个氨基氧基之间的分子内电荷转移相互作用的可能性5)(为了在解释所观察到的UV吸收CA。328纳米),并且还-1-吡咯啉-1-氧化物的二聚化(特别是那些在空间上很拥挤),简要讨论。