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Your search keyword '"Uccello Barretta G"' showing total 165 results
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165 results on '"Uccello Barretta G"'

3. Asymmetric induction by the cholestanic moiety on tropos species: Synthesis and stereochemical characterization of bile acid-based biphenyl phosphites

Author

Iuliano, A., Facchetti, S., and Uccello-Barretta, G.

Subjects
Bile acids -- Chemical properties, Stereochemistry -- Analysis, Biological sciences, Chemistry
Abstract

The capability of the cholestanic moiety to induce a prevalent screw sense on the tropos unit of biphenyl phosphite was investigated to obtain bile acid-based biphenyl phosphites to be used in asymmetric catalysis. The bile acid moiety is capable of exerting asymmetric induction on the sense of twist of the biphenyl unit of the biphenyl phosphite appendage linked at the position 3 at low temperature (-80 degree Celsius), affording a prevalence (65:35) of one diastereoisomer on the other.

Published
2006

4. Synergistic effects of trace amounts of water in the enantiodiscrimination processes by lipodex E: a spectroscopic and computational investigation

Author

Uccello-Barretta, G, Volker, S, Balzano, F, Vanni, L, Aiello, F, Mori, M, and Ghirga, F

Subjects
Pharmacology, Cyclodextrins, Magnetic Resonance Spectroscopy, Molecular Structure, Drug Discovery3003 Pharmaceutical Science, Medicine (all), Organic Chemistry, Water, Stereoisomerism, Molecular dynamics, Molecular Dynamics Simulation, NMR Spectroscopy, Catalysis, Analytical Chemistry, Host-guest systems, Cyclohexanes, Solvents, Chirality, Propionates, gamma-Cyclodextrins, Spectroscopy
Abstract

Nuclear magnetic resonance (NMR) investigations on mixtures containing octakis(3-O-butanoyl-2,6-di-O-pentyl)-γ-cyclodextrin (Lipodex E) and each enantiomer of methyl-2-chloropropionate (MCP) ascertained the role of trace amounts of water in the enantiodiscrimination processes. Water is deeply included into the cyclodextrin and favors the formation of the inclusion complex with (S)-MCP, whereas (R)-MCP is only slightly affected, thus causing a significant increase of NMR differentiation. Molecular dynamics simulations were performed to shed light on the possible behavior of Lipodex E in different conditions (i.e., solvent, inclusion complexes), providing energetic and atomistic details that are in agreement with NMR observations.

Published
2014

5. Alder-ene addition of maleic anhydride to polyisobutene: Nuclear magnetic resonance evidence for an unconventional mechanism

Author

Balzano F., Pucci A., Rausa R., and Uccello-Barretta G.

Subjects
High resolution NMR, Polyisobutene functionalization, Alder-ene mechanism, Maleic anhydride
Abstract

In this work, the thermal Alder-ene functionalization of highly reactive, vinylidene-terminated, polyisobutene (PIB) with stoichiometric amounts of maleic anhydride at 200 °C was investigated by NMR spectroscopy. The thorough interpretation of the complex NMR spectra of PIB derivatives collected at different reaction times (from 4 to 21 h) was based on the combined use of one- and two-dimensional techniques which allowed the precise structure of all the reaction products as well as their relative content to be ascertained. The analysis evidenced the formation of large amounts of derivatives generated by the classic Alder-ene mechanism and involving the more reactive vinylidene 'exo' double bonds of PIB. More interestingly, the investigation also the investigation allowed also to detect the formation of a noteworthy amount of not expected structure generated by the thermal maleination of the less reactive PIB 'endo' ?-form provided by the isomerization of residual PIB 'exo' ?-form during the functionalization reaction. © 2012 Society of Chemical Industry.

Published
2012
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11. C11 vs C9 carbamoylation of quinine: a new class of versatile polyfunctional chiral solvating agents

Author

Uccello-Barretta G., Mirabella F., Balzano F., and Salvadori P.

Abstract

Carbamoyl derivatives of quinine obtained by derivatization of its double bond have been prepared and used as chiral solvating agents for NMR spectroscopy: their efficiency reproduces very well that of quinine and its C9 carbamates in enantiodiscriminating underivatized and derivatized chiral substrates, respectively.

Published
2003

47. [PtCl<INF>3</INF>(C<INF>2</INF>H<INF>4</INF>)]<SUP>-</SUP>[(S,S)-(PhMeCH)<INF>2</INF>NH<INF>2</INF>]<SUP>+</SUP>:  A New and Versatile Ionic Organometallic Chiral Derivatizing Agent for the Determination of the Enantiomeric Composition of Chiral Unsaturated Compounds by <SUP>195</SUP>Pt NMR Spectroscopy

Author

Uccello-Barretta, G., Bernardini, R., Lazzaroni, R., and Salvadori, P.

Abstract

The ionic complex [PtCl3(C2H4)]-[(S,S)-(PhMeCH)2NH2]+ containing a chiral secondary amine is a new and versatile chiral derivatizing agent (CDA) for the determination of the enantiomeric composition of several unsaturated compounds including simple olefins:  the diastereoisomeric mixtures arising from the exchange of ethylene by the unsaturated analytes are easily detected by 195Pt NMR spectroscopy.

Published
2000

48. On the high efficiency of cis-dichloro[(S)-a-methylbenzylamine](ethylene)platinum(II) as chiral derivatizing agent for the determination of the enantiomeric composition of chiral unsaturated ethers by 195Pt-NMR spectroscopy: a spectroscopic conformational and configurational characterization in solution of diastereoisomeric complexes cis-dichloro[(S)-a-methylbenzylamine][(S)- and (R)-3-phenyl-3-methoxybut-1-ene]platinum(II)

Author

Uccello-Barretta, G., Bernardini, R., Balzano, F., Lazzaroni, R., and Salvadori, P.

Published
2000
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