2,5-Di-tert-butyl-2,5-diethylpyrrolidine-1-oxyls: Where Is a Reasonable Limit of Sterical Loading for Higher Resistance to Reduction?

• Autor: Zhurko, Irina F ; Dobrynin, Sergey A ; Glazachev, Yurii I ; Gatilov, Yuri V ; Kirilyuk, Igor A
• Assuntos: 1,3-dipolar cycloaddition ; Amino acids ; azomethine ylide ; EPR ; Free radicals (Chemistry) ; Hydrogen ; Oxidation ; reduction-resistant nitroxide ; three-component domino reaction
• É parte de: Molecules (Basel, Switzerland), 2024-01, Vol.29 (3), p.599
• Notas: ObjectType-Article-1
  SourceType-Scholarly Journals-1
  ObjectType-Feature-2
  content type line 23
  
• Descrição: The pyrrolidine nitroxides with four bulky alkyl substituents adjacent to the N-O∙ group demonstrate very high resistance to reduction with biogenic antioxidants and enzymatic systems. This makes them valuable molecular tools for studying the structure and functions of biomolecules directly in a living cell and for functional EPR and NMR tomography in vivo. The first example of highly strained pyrrolidine nitroxides with both ethyl and -butyl groups at each of the α-carbon atoms of the nitroxide moiety with -configuration of the -butyl groups was prepared using a three-component domino reaction of -leucine and 2,2-dimethylpentan-3-one with dimethyl fumarate with subsequent conversion of the resulting strained pyrrolidine into 1-pyrroline-1-oxide and addition of EtLi. The nitroxide has demonstrated unexpectedly fast reduction with ascorbate, the rate constant = (2.0 ± 0.1) × 10 M s . This effect was explained by destabilization of the planar nitroxide moiety due to repulsion with the two neighboring -butyl groups to each other.
  
• Editor: Switzerland: MDPI AG
  
• Idioma: Inglês