304-28-9Relevant articles and documents
Stereoselective Postassembly CH Oxidation of Self-Assembled Metal-Ligand Cage Complexes
Holloway, Lauren R.,Bogie, Paul M.,Lyon, Yana,Julian, Ryan R.,Hooley, Richard J.
, p. 11435 - 11442 (2017)
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 tBuOOH, 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 tBuOOH, the unfavorability of the self-assembled ketone cages forces the reaction to form the tbutyl 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.
Selective Preparation of Fluorene Derivatives Using the t-Butyl Function as a Positional Protective Group
Kajigaeshi, Shoji,Kadowaki, Toshiya,Nishida, Akiko,Fujisaki, Shizuo
, p. 97 - 104 (2007/10/02)
Several 4-substituted 2,7-di-t-butylfluorene derivatives (3) were prepared by electrophilic substitutions of 2,7-di-t-butylfluorene (1). 4-Substituted fluorene (4), such as 4-bromo- (4a), 4-methyl (4e), and 4-aacetylaminofluorene (4j), were obtained by the trans-t-butylations of 3.Although we attempted to synthesize 1,8-disubstituted fluorene from 3,6-di-t-butylfluorene (2) which was derived from 2,2'-diiodo-4,4'-di-t-butyldiphenylmethane (5), by the same methods, we obtained only 2,7-disubstituted fluorene derivatives (8); it turned out electrophilic substitutions of 2 gave 2,7-disubstituted 3,6-di-t-butylfluorene derivatives.