Stereochemical assignment of 2-amino-1,2,3,4-tetrahydro-1-naphthalenols via oxazolidin-2-one derivatives

Abstract

The stereochemical assignment of cis- and trans-2-amino-1,2,3,4-tetrahydro-1-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.