Synthesis of 1,3,4,5‐Tetrahydro‐2‐benzoxepin Derivatives as Conformationally Restricted Analogues of cyclamenaldehyde‐type compounds and as intermediates for highly odour‐active homologues

Abstract

Abstract Nine 1,3,4,5‐tetrahydro‐2‐benzoxepin derivatives have been prepared as mimics of the folded ( gauche ) conformation of cyclamenaldehyde ( 1 ) and related compounds, but none of them showed the typical lily‐of‐the valley (muguet) odour activity. However, conversion of these substances to previously unknown analogues of 1 having a Me substituent on the aromatic ring in an ortho position to the side chain led to new fragrance substances with remarkable properties. The results indicate that the extended ( anti ) conformation is more likely to be the ‘bioactive’ one at the receptor site(s).