664987-32-0Relevant articles and documents
Mechanistically Driven Development of an Iron Catalyst for Selective Syn-Dihydroxylation of Alkenes with Aqueous Hydrogen Peroxide
Borrell, Margarida,Costas, Miquel
supporting information, p. 12821 - 12829 (2017/09/25)
Product release is the rate-determining step in the arene syn-dihydroxylation reaction taking place at Rieske oxygenase enzymes and is regarded as a difficult problem to be resolved in the design of iron catalysts for olefin syn-dihydroxylation with potential utility in organic synthesis. Toward this end, in this work a novel catalyst bearing a sterically encumbered tetradentate ligand based in the tpa (tpa = tris(2-methylpyridyl)amine) scaffold, [FeII(CF3SO3)2(5-tips3tpa)], 1 has been designed. The steric demand of the ligand was envisioned as a key element to support a high catalytic activity by isolating the metal center, preventing bimolecular decomposition paths and facilitating product release. In synergistic combination with a Lewis acid that helps sequestering the product, 1 provides good to excellent yields of diol products (up to 97% isolated yield), in short reaction times under mild experimental conditions using a slight excess (1.5 equiv) of aqueous hydrogen peroxide, from the oxidation of a broad range of olefins. Predictable site selective syn-dihydroxylation of diolefins is shown. The encumbered nature of the ligand also provides a unique tool that has been used in combination with isotopic analysis to define the nature of the active species and the mechanism of activation of H2O2. Furthermore, 1 is shown to be a competent synthetic tool for preparing O-labeled diols using water as oxygen source.
Fluoride ion-promoted α-ketol rearrangement during unmasking of silyl-protected medium-ring dihydroxy ketones
Hartung, Ryan E.,Hilmey, David G.,Paquette, Leo A.
, p. 713 - 716 (2007/10/03)
A new strategy for implementing α-ketol rearrangements under mild conditions is presented. The reactants are mono- and disilylated stereoisomers of α,α′- and α,β-dihydroxycycloheptanones and -cyclooctanones. Compounds of this class experience ready deprotection upon treatment with tetrabutyl-ammonium fluoride. In certain examples, this process is accompanied by structural isomerization. Since the product diols are stable to the reaction conditions, these chemical changes have been attributed to kinetically controlled events following transient alkoxide generation resulting from cleavage of the O-Si bond proximal to the carbonyl group. The experimental findings are evaluated against a backdrop of calculated (MM3) steric energies of the silicon-free products and their response to equilibration under strongly basic conditions.
