Influence of amino acid stereocenters on the formation of bicyclic N, O -acetals

  1. Jiménez-Osés, G. 2
  2. Aydillo, C. 1
  3. Busto, J.H. 1
  4. Zurbano, M.M. 1
  5. Peregrina, J.M. 1
  6. Avenoza, A. 1
  1. 1 Universidad de La Rioja
    info

    Universidad de La Rioja

    Logroño, España

    ROR https://ror.org/0553yr311

  2. 2 University of California Los Angeles
    info

    University of California Los Angeles

    Los Ángeles, Estados Unidos

    ROR https://ror.org/046rm7j60

Revista:
Journal of Organic Chemistry

ISSN: 0022-3263

Año de publicación: 2014

Volumen: 79

Número: 6

Páginas: 2556-2563

Tipo: Artículo

DOI: 10.1021/JO500015C SCOPUS: 2-s2.0-84896999419 WoS: WOS:000333477500020 GOOGLE SCHOLAR

Otras publicaciones en: Journal of Organic Chemistry

Resumen

In recent years, our group has reported the highly diastereoselective acid-catalyzed N,O-acetalization/intramolecular transcarbamoylation cascade of reactions between protected α-amino acid derivatives (Ser and Thr) and tetramethoxyalkanes. The resulting oligocyclic N,O-acetals have been used as excellent chiral building blocks for asymmetric transformations such as diastereoselective alkylation of the α-position. We now evaluate the scope of the reaction with related non-natural α-amino acid derivatives. A combined experimental and theoretical study reveals the key influence of the α-carbon substitution (serine versus α-methylserine) and the relative configuration of α-/β-carbons (threonine versus allo-threonine) in the thermodynamic stability of the products and, as a consequence, the stereochemical outcome of the reaction. Notably, the complete diastereoselectivity achieved with natural amino acid precursors is completely lost with their non-natural analogues. © 2014 American Chemical Society.