Hedione®

Synthesis route :

Hedione® is synthesized from a condensation between cyclopentanone and valeraldehyde, followed by an isomerization of the intermediate product obtained to give 2-pentyl-2-cyclopenten-1-one. This molecule can undergo a Michael addition by reacting it with an alkyl malonate. A hydrolysis followed by a decarboxylation and finally an esterification (using methanol and an acid catalysis) of the acid function that has formed, allows to synthesize the final product, Hedione®.

Synthesis precursor :

The classic Hedione® is a mixture of isomers, it is used to isolate Hedione® HC (High Cis), a superior olfactory quality and power (also to be notes : Cepionate®, Kharismal® and Paradisone®)

Isomerism :

Hedione®, commonly used in perfumery, is actually a 9:1 mixture of trans:cis diastereoisomers of the molecule. However, cis-Hedione® is the most powerful isomer. Its detection threshold is seventy times lower than trans-Hedione®. Thus, some Hedione® enriched in cis isomer are marketed: Cepionate® (30% cis), Kharismal® (60% cis) and Hedione® HC (for ''high cis '') (75% cis). Nevertheless, this Hedione® tends to be more unstable than the classic Hedione®, as it isomerizes in its trans form, more stable. Hedione® HC is prepared by a specific distillation technique that involves sodium carbonate. Another method is to hydrogenate the corresponding cyclopenteneacetic acid by a ruthenium II catalysis, followed by a methanol esterification of the acid function.