1-benzyl-1,2,3,4-tetrahydroisoquinolines: ¹h nmr conformational studies and rotational barriers

• PATRICIO ITURRIAGA-VÁSQUEZ ^[1] ; GERALD ZAPATA-TORRES ^[1] ; MARCOS CAROLI REZENDE ^[2] ; BRUCE K. CASSELS ^[1]
  1. [1] Universidad de Chile

     Universidad de Chile

     Santiago, Chile

     
  2. [2] University of Santiago Faculty of Chemistry and Biology Department of Chemistry
• Localización: Journal of the Chilean Chemical Society (Boletín de la Sociedad Chilena de Química), ISSN-e 0717-6309, ISSN 0366-1644, Vol. 49, Nº. 1, 2004, págs. 17-23
• Idioma: inglés
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• Resumen

  • The conformational preferences of a series of 1-benzyl-1,2,3,4-tetrahydroisoquinolines (norlaudanosine and coclaurine analogues) were investigated with the aid of their 1H NMR spectra and NOESY experiments, coupled with ab initio theoretical studies to estimate energy barriers among the various stable conformers of these systems. The secondary amines prefer an extended conformation, while the N-alkylated derivatives prefer a semi-folded one, with considerable freedom to exchange between both forms. A third, folded conformation, although not much higher in energy, is relatively inaccessible