Synthesis and Properties of Conformationally Constrained Analogues of Floral‐Type Odorants

The twelve bridged analogues 8 – 19 of floral‐type odorants related to cyclamenaldehyde ( 1 ) were synthesized (Schemes 1–5) to investigate the relationship between the structural and conformational features of these compounds and their odor properties. Comparison of the data from sensory evaluation and molecular modeling suggests that the side chain of both the unconstrained and the constrained active analogues is not extended (anti) but rather folded (gauche) in the ‘bioactive’ conformation. However, it is mainly the nature of the substituents at the α position of the aldehyde function that critically influences the odor quality and strength. These studies provide new information that should aid ongoing efforts to develop models of odorant? receptor interactions.