Understanding the Unusual Regioselectivity in the Nucleophilic Ring-Opening Reactions of gem-Disubstituted Cyclic Sulfates. Experimental and Theoretical Studies

  1. Avenoza, A. 1
  2. Busto, J.H. 1
  3. Corzana, F. 1
  4. García, J.I. 2
  5. Peregrina, J.M. 1
  1. 1 Universidad de La Rioja
    info

    Universidad de La Rioja

    Logroño, España

    ROR https://ror.org/0553yr311

  2. 2 Instituto de Nanociencia y Materiales de Aragón
    info

    Instituto de Nanociencia y Materiales de Aragón

    Zaragoza, España

    ROR https://ror.org/031n2c920

Revista:
Journal of Organic Chemistry

ISSN: 0022-3263

Año de publicación: 2003

Volumen: 68

Número: 11

Páginas: 4506-4513

Tipo: Artículo

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DOI: 10.1021/JO034178Q SCOPUS: 2-s2.0-0037764769 WoS: WOS:000183066100047 GOOGLE SCHOLAR

Otras publicaciones en: Journal of Organic Chemistry

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Resumen

The regioselectivity of the nucleophilic ring-opening reactions of three gem-disubstituted cyclic sulfates with sodium azide has been studied from both experimental and theoretical viewpoints. It is found that, depending on the substituent present in the cyclic sulfate, the reaction displays reversed regioselectivity, which allows one or another regioisomer to be obtained with selectivities greater than 4:1. The theoretical calculations show that, contrary to previous understanding, the intrinsic preference in all cases is azide attack at the less-substituted Cβ position, a consequence of similar stereoelectronic effects in the three sulfates considered. The observed preference for Cα attack in the case of the ester sulfate is explained in terms of differential solvent effects, which are in turn due to subtle differences in the charge transfer in the different transition structures.