Chirality in the Absence of Rigid Stereogenic Elements: The Design of Configurationally Stable C3-Symmetric Propellers (Articolo in rivista)

Type
Label
  • Chirality in the Absence of Rigid Stereogenic Elements: The Design of Configurationally Stable C3-Symmetric Propellers (Articolo in rivista) (literal)
Anno
  • 2009-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1002/chem.200801505 (literal)
Alternative label
  • Benincori, T.; Marchesi, A.; Pilati, T.; Ponti, A.; Rizzo, S.; Sannicolo, F. (2009)
    Chirality in the Absence of Rigid Stereogenic Elements: The Design of Configurationally Stable C3-Symmetric Propellers
    in Chemistry - A European Journal
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Benincori, T.; Marchesi, A.; Pilati, T.; Ponti, A.; Rizzo, S.; Sannicolo, F. (literal)
Pagina inizio
  • 94 (literal)
Pagina fine
  • 105 (literal)
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  • 15 (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#note
  • DOI: 10.1002/chem.200801505 (literal)
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • [a] Prof. T. Benincori Dipartimento di Scienze Chimiche ed Ambientali Universit? dell'Insubria via Valleggio 11, 22100 Como (Italy) [b] Dr. A. Marchesi Laboratori Alchemia s.r.l. via S. Faustino 68, 20134 Milano (Italy) [c] Dr. T. Pilati, Dr. A. Ponti, Dr. S. Rizzo, Prof. F. Sannicol? Istituto di Scienze e Tecnologie Molecolari Consiglio Nazionale delle Ricerche via Golgi 19, 20133 Milano (Italy) Fax: (+39) 0250314300 E-mail: alessandro.ponti@istm.cnr.it [d] Prof. F. Sannicol? Dipartimento di Chimica Organica e Industriale C.I.MA.I.NA., Universit? di Milano via Venezian 21, 20133 Milano (Italy) Fax: (+39) 0250314139 E-mail: francesco.sannicolo@unimi.it (literal)
Titolo
  • Chirality in the Absence of Rigid Stereogenic Elements: The Design of Configurationally Stable C3-Symmetric Propellers (literal)
Abstract
  • Residual stereoisomerism is a form of stereoisomerism scarcely considered so far for applicative purposes, though extremely interesting, since the production of stereoisomers does not involve classical rigid stereogenic elements. In three-bladed propeller-shaped molecules, a preferred stereomerization mechanism, related to the correlated rotation of the rings, allows the free interconversion of stereoisomers inside separated sets (the residual stereoisomers) that can inter-convert through higher energy pathways. In light of possible future applications as chiral ligands for transition metals in stereoselective processes, some C-3-symmetric phosphorus-centered propellers, which could exist as residual enantiomers, are synthesized and the possibility of resolving their racemates into residual antipodes is explored. While the tris(aryl)methanes are configurationally stable at room temperature, only selected tris(aryl)phosphane oxides display a configurational stability high enough to allow resolution by HPLC on a chiral stationary phase (CSP HPLC) at a semipreparative level at room temperature. Stability was evaluated through different techniques (circular dichroism (CD) signal decay, dynamic CSP HPLC (CSP DHPLC), dynamic NMR analysis (DNMR)) and the results compared and discussed. Phosphanes were found much less stable than the corresponding phosphane oxides, for which preliminary calculations suggest that the three-ring-flip enantiomerization mechanism (M,) would be easier than phosphorus pyramidal inversion. The parameters affecting the configurational stability of the residual enantionters of C-3-symmetric propellers are discussed. (literal)
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