Holloway Lauren R, Bogie Paul M, Lyon Yana, Julian Ryan R, Hooley Richard J
Department of Chemistry, University of California-Riverside , Riverside, California 92521, United States.
Inorg Chem. 2017 Sep 18;56(18):11435-11442. doi: 10.1021/acs.inorgchem.7b01958. Epub 2017 Aug 25.
Self-assembled Fe-iminopyridine cage complexes containing doubly benzylic methylene units such as fluorene and xanthene can be selectively oxidized at the ligand backbone with BuOOH, with no competitive oxidation observed at the metal centers. The self-assembled cage structure controls the reaction outcome, yielding oxidation products that are favored by the assembly, not by the reactants or functional groups. Whereas uncomplexed xanthene and fluorene control ligands are solely oxidized to the ketone equivalents with BuOOH, the unfavorability of the self-assembled ketone cages forces the reaction to form the butyl peroxide and alcohol-containing oxidation products, respectively. In addition, the oxidation is diastereoselective, with only single isomers of the cage assemblies formed, despite the presence of as many as 10 stereocenters in the final product. The self-assembled structures exploit self-complementary hydrogen bonding and geometrical constraints to direct the postassembly reactions to outcomes not observed in free solution. This selectivity is reminiscent of the fine control of post-translational modification seen in biomacromolecules.
含有芴和呫吨等双苄基亚甲基单元的自组装铁-亚氨基吡啶笼状配合物，可用叔丁基过氧化氢在配体主链上进行选择性氧化，在金属中心未观察到竞争性氧化。自组装笼状结构控制反应结果，生成的氧化产物是组装体所青睐的，而非反应物或官能团所青睐的。未络合的呫吨和芴控制配体用叔丁基过氧化氢仅被氧化为酮类似物，而自组装酮笼状结构的不利性分别迫使反应形成过氧化丁基和含醇的氧化产物。此外，氧化反应具有非对映选择性，尽管最终产物中存在多达10个立体中心，但仅形成笼状组装体的单一异构体。自组装结构利用自互补氢键和几何限制，将组装后反应导向在自由溶液中未观察到的结果。这种选择性让人联想到生物大分子中翻译后修饰的精细控制。
