Polarity Reversal Catalysis Research Articles

Inhibition of Rearrangements in Stannane-Mediated Radical Reduction Reactions by Catalytic Quantities of Diphenyl Diselenide. An Example of Polarity Reversal Catalysis

The presence of only 10 mol % of PhSeH, PhSeSePh (reduced in situ to PhSeH), and, to a lesser extent, PhSH has a dramatic effect on the efficiency of stannane-mediated free radical rearrangement reactions owing to the superior hydrogen donating qualities of PhSeH and PhSH. Slow radical rearrangements can be prevented altogether, and the yields of even moderately rapid rearrangements significantly diminished. The addition of 10 mol % of PhSeSePh to stannane-mediated aryl radical cyclizations is advantageous as the initial, rapid, 5-hexenyl rearrangement is not impaired but the subsequent, slower neophyl rearrangement is effectively minimized, resulting in the formation of vastly improved 5-exo/6-endo ratios. 2 tabs.

Homolytic reactions of ligated boranes. Part 18. The scope of enantioselective hydrogen-atom abstraction by chiral amine–boryl radicals for kinetic resolution under conditions of polarity reversal catalysis

Download options Please wait... Article information DOI https://doi.org/10.1039/P19940001033 Article type Paper Download Citation J. Chem. Soc., Perkin Trans. 1, 1994, 1033-1041 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Homolytic reactions of ligated boranes. Part 18. The scope of enantioselective hydrogen-atom abstraction by chiral amine–boryl radicals for kinetic resolution under conditions of polarity reversal catalysis H. Dang, V. Diart and B. P. Roberts, J. Chem. Soc., Perkin Trans. 1, 1994, 1033 DOI: 10.1039/P19940001033 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Hai-Shan Dang Valérie Diart Brian P. Roberts

ChemInform Abstract: Polarity Reversal Catalysis of Radical Reactions: Hydrogen‐Atom Abstraction from Cyclopentadiene and from Cycloheptatriene.

AbstractIn the absence of catalyst (cat.) both radicals (III) and (IV) are observed (ESR) from tBuO· attack on cyclopentadiene (I) while in the presence of cat.

Polarity reversal catalysis of hydrogen atom abstraction reactions

Overall transfer of electron deficient hydrogen to the electrophilic t-butoxyl radical is catalysed by Me3N → BH2Hext; hydrogen atom abstraction is actually brought about by the nucleophilic Me3N → ḂHHext.