Stereochemical assignment of 2-amino-l,2,3,4-tetrahydro-l-naphthalenols via oxazolidin-2-one derivatives

Abstract

The stereochemical assignment of cis- and trans-2-amino-1,2,3,4-tetrahydro-l-naphthalenols (1) can be performed by means of their conformationally restrained tricyclic tetrahydronaphtho[2,1-d]oxazol-2-one derivatives 2-6. Thus, 1H and 13C nuclear magnetic resonance data of compounds 2-6 reveal differences between the cis and trans stereoisomers that are independent of the nature and number of the aromatic substituents. Conformational analysis of compounds 2-6 has been performed from the LAOCOON/3 analysis of their nuclear magnetic resonance spectra and MNDO theoretical results, through the use of the Karplus-Altona equation. Whereas the trans compounds exist in a rigid half-chair conformation, a 1:1 equilibrium of two interconverting half-chair conformers is found for the cis derivatives.