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Selective synthesis of aminoalcohols by hydroxyalkylation of amines in alcohol or in cyclic ether cosolvents: a new domino radical mechanism promoted by TiCl4-Zn/t-BuOOH
No full textMILD OXIDATION OF ALKYLAROMATICS TO CORRESPONDING HYDROPEROXIDES CATALYSED BY N-HYDROXY DERIVATIVES
No full textMulticomponent versus domino reactions: One-pot freeradical synthesis of ??-amino-ethers and ??-amino-alcohols
Full text linkFollowing an optimized multicomponent procedure, an aryl amine, a ketone, and a cyclic ether or an alcohol molecule are assembled in a one-pot synthesis by nucleophilic radical addition of ketyl radicals to ketimines generated in situ. The reaction occurs under mild conditions by mediation of the TiCl4/Zn/t-BuOOH system, leading to the formation of quaternary β-amino-ethers and -alcohols. The new reaction conditions guarantee good selectivity by preventing the formation of secondary products. The secondary products are possibly derived from a competitive domino reaction, which involves further oxidation of the ketyl radicals
New Advances in Titanium-Mediated Free Radical Reactions
No full textTitanium complexes have been widely used as catalysts for C‑C bond-forming processes via free-radical routes. Herein we provide an overview of some of the most significant contributions in the field, that covers the last decade, emphasizing the key role played by titanium salts in the promotion of selective reactions aimed at the synthesis of multifunctional organic compounds, including nucleophilic radical additions to imines, pinacol and coupling reactions, ring opening of epoxides and living polymerization
New domino radical synthesis of aminoalcohols promoted by TiCl4–Zn/t-BuOOH system: selective hydroxyalkylation of amines in alcohol or in cyclic ether cosolvents
No full text
AEROBIC OXIDATION OF ALKYLAROMATICS TO CORRESPONDING HYDROPEROXYDES CATALYSED BY N-HYDROXY IMIDES
No full textDifferent N-hydroxyphthalimide (NHPI) derivatives were investigated as catalyst for the aerobic oxidation of alkylaromatics,
including cumene, phenylcyclohexane and ethylbenzene, leading to the corresponding hydroperoxides in good yields and high
selectivity.
The employment of different initiators among a large number of aldehydes, the nature of the solvent and the effect of the
temperature, were carefully analysed.
The progressive reduction of the solvent-alkylaromatic volumetric ratio was also investigated in order to make the proposed
approach suitable for industrial applications.
The issue related to the low solubility of the NHPI in less polar reacting mixtures was effectively worked out by the use of more
lipophilic catalysts. In particular, while using aldehydes as initiator, the presence of two or more N-hydroxy moieties on the same
molecule seems to be advantageous in order to get better chemical efficiencies respect to molecules bearing a single N-hydroxy
group. Bond energy measurements and kinetic data by EPR spectroscopy are also presented as a valid support for explaining the
experimental data.
The recovery and reuse of the catalyst was obtained through a reversible adsorption onto non-basic amberlyst resins followed by
its desorption using non-protic polar solvents. The proposed approach seems to be of particular interest for the industrial
application.
The sunlight photocatalytic oxidation of cumene to hydroperoxide by organic n-semiconductors in presence of NHPI was also
investigated
MILD OXIDATION OF ALKYLAROMATICS TO CORRESPONDING HYDROPEROXIDES CATALYSED BY N-HYDROXY DERIVATIVES
No full textThe catalytic activity of different N-hydroxyphthalimide (NHPI)1 derivatives was investigated in the oxidation of alkylaromatics, including cumene,2,3 phenylcyclohexane2,4 and ethylbenzene,4,5 leading to the corresponding hydroperoxides in good yields and high selectivity.
The employment of different initiators among a large number of aldehydes, together with the nature of the solvent and the effect of the temperature, was carefully analysed.
In order to make the proposed approach suitable for industrial applications, the progressive reduction of the solvent-alkylaromatic volumetric ratio was also investigated.
In particular, the issue related to the low solubility of the NHPI in less polar reacting mixtures was effectively worked out by the use of more lipophilic molecules bearing N-hydroxy moieties.6
The relevancy of the proposed process is particularly apparent when considering the extremely mild operative conditions. Bond energy measurements by EPR spectroscopy are also presented as a valid support for explaining the experimental data
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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