New Norbornyl Derivatives as Woody Fragrant Materials

Abstract

The optimization of a Diels-Alder reaction to prepare a novel ketone bearing a 2,3-dimethylnorbornyl group is presented together with the structure elucidation of the isomers. Employing this new ketone as starting material, derivatives with new woody odor notes as well as attempts to obtain ambery-musky odorants are reported.

Synthesis and odour evaluation of alcohols bearing a cis‐1,2‐dimethyl norbornane moiety

“…Starting from the readily available Presantone H®, 1‐ exo , the olefin 2 was obtained in 90% yield via a Wittig reaction with methyltriphenylphosphonium bromide and t ‐BuOK (Equation 1):…”

“…We have been interested by the preparation of woody‐like molecules that have some structural similarity to β ‐santalol. A patent on the synthesis of Presantone® leading to the preparation of Legnox®, a mixture of isomers presenting a strong woody character, has been published, as well as the synthesis of several other derivatives . Among them, Presantone H®, 1‐ exo , has been obtained by hydrogenation of Presantone®, followed by fractional distillation (Scheme ).…”

Synthesis of New exo‐ and endo‐3,8‐Dihydro‐β‐santalols and Other Norbornyl‐Derived Alcohols

“…All of the reagents and solvents were commercially available, and were used without any further purification when not specified. Spectral data of compounds 5 and 6 (exo/endo) have already been reported [23]. All reactions were carried out in small-to-large scale (1 g to 100 g or more).…”

“…A few years ago, a patent filed by Mane et al [22] reported that derivatives of 2,3-dimethylnorbornenyl methyl ketone 5 (Scheme 1) presented some interesting woody notes, and several norbornyl derivatives of 5 and 6 were further described [23].…”

“…Pure exo-and endo-isomers of 6 were obtained by distillation on a 500-g scale. Complete structural assignments for both isomers were accomplished by 1D-and 2D-NMR analysis, and the structure of endo-6 was further confirmed by an X-Ray crystallographic analysis of the corresponding oxime endo-7 [23].…”