Synthesis of cis-jasmone
cis-Jasmone is one of the components of jasmine scent and is used in perfumery. Many of its syntheses end with an intramolecular aldol condensation of (Z)-undec-8-ene-2,5-dione.
The 1,4-diketone can form several enolates, but only one of them, that of the CH2 next to C5, leads to a five-membered ring on attacking C2; dehydration gives the conjugated cyclopentenone. The Z double bond of the side chain is not affected.