Synthesis and Qualitative Olfactory Evaluation of Benzodioxepine Analogues

Marine fragrances, particularly Calone 1951 (R) (= 7-methyl-2H- 1,5 -benzodioxepin-3 (4H) -one; 1) has carved a minor but distinct niche in the broad field of fragrance chemistry. By focusing on the polar structure fragment of the benzodioxepinone parent compound, we set out to determine the molecular influence on the dominant marine note attributed to the Calone 1951 (R) structure. A selection of one-step modifications of the ketone 1 resulted in a range of odor-active conformers with diverse olfactory attributes. The synthesis of a range of benzodioxepine analogues, i.e., of 3-11, is presented alongside olfactory evaluation (Tables 2 and 3). Removal of the carbonyl group of 1 and increasing the size of the aliphatic ring portion (see 6 and 7) introduced sweetness and a predominant loss of the marine character.