RESUMO
Electrochemical studies of the reduction and oxidation reactions of five different organic nitroxyls have been performed across a wide pH range (0-13). The resulting Pourbaix diagrams illustrate structural effects on their various redox potentials and on the p Ka values of the corresponding hydroxylamine and hydroxylammonium ions. Evidence is also given for the reversible formation of a hydroxylamine N-oxide when nitroxyls are oxidized in alkaline media. Structural effects on the thermodynamics of this reaction are assessed.
Assuntos
Compostos Azabicíclicos/química , Óxidos N-Cíclicos/química , Catálise , Técnicas Eletroquímicas , Concentração de Íons de Hidrogênio , Estrutura Molecular , OxirreduçãoRESUMO
The asymmetric desymmetrization of 4,6-diprotected myo-inositol derivatives was achieved by using a bifunctional, readily available nucleophilic catalyst. The orthogonally protected products were obtained in 80-99% yield with 90-99% ee. Such structures serve as potential enantiopure building blocks for the synthesis of myo-inositol phosphates.
Assuntos
Fosfatos de Inositol/síntese química , Inositol/análogos & derivados , Catálise , Fosfatos de Inositol/química , EstereoisomerismoRESUMO
This paper focuses on readily accessible thiourea hydrogen bond catalysts derived from amino acids, whose steric and electronic features are modulated by their degree of substitution at the carbinol carbon center. These catalysts were applied in the asymmetric transfer hydrogenation of nitroolefins furnishing the chiral products in up to 99% yield and 86% enantiomeric excess. The proposed catalyst's mode of action is supported by mechanistic investigations.