Pomarose is a high-impact captiveodorant patented by Givaudan.[1] It is a double-unsaturated ketone that does not occur in nature. Pomarose has a powerful fruity rose odor with nuances of apples, plums and raisins, which is almost entirely due to the (2E,5Z)-stereoisomer, while its (2E,5E)-isomer is barely detectable for most people.[2] Catalyzed by traces of acids, both isomers equilibrate however quickly upon standing in glass containers.
5,6,7-Trimethylocta-2,5-dien-4-one was suspected by Philip Kraftet al.[3] by investigation of the NMR spectra of an unknown trace component with damascone odor in a crude complex reaction product. Although this trace component eventually turned out to be the constitutional isomer 2-methyl-3-isopropylhepta-2,5-dien-4-one. Pomarose was synthesized for structural curiosity and found to possess even superior fruity, rosy odor characteristics, reminiscent of apples, plums, raisins and other dried fruits with a low odor threshold of 0.5 ng/L air. The synthesis comprised borontrifluoride-catalyzed addition of methyl isopropyl ketone to 1-ethoxyprop-1-yne, which afforded ethyl 2,3,4-trimethylpent-2-enoate, and then was transformed into the target molecule by Grignard reaction with propen-1-ylmagnesium bromide via in situ enolization.
Pomarose has been used in a variety of perfumes.[4] It had its debut in Be Delicious for Men and it is also used in Unforgivable, 1 Million, CK free, Legend, Unforgivable Woman and John Galliano.
^Kraft, Philip (2001). "Preparation of 2-,5-,6-,7-,8-substituted oct-2-en-4-ones with odor and taste properties". Eur. Pat. Appl. 2001: EP 1149820 A1 20011031.
^Kraft, Philip; Denis, Caroline; Eichenberger, Walter (2001). "5,6,7-Trimethylocta-2,5-dien-4-one − A Suspected Odorant with Surprising Olfactory Properties". European Journal of Organic Chemistry. 2001 (12): 2363–2369. doi:10.1002/1099-0690(200106)2001:12<2363::AID-EJOC2363>3.0.CO;2-E.
