Chemistry:2,5-Undecanedione
2,5-Undecanedione is a γ-diketone in which the two carbonyl groups are separated by two methylene groups.
Synthesis
Heinz Hunsdiecker described the synthesis of 2,5-undecanedione from 5-methylfurfural in 1942. 5-Methylfurfural 1 is first reacted with methyl propyl ketone 2 in an aldol condensation reaction to form an α,β-unsaturated carbonyl compound 3. The double bond of the side chain condensation product is reduced with sodium amalgam. The intermediate 4 is then converted to 2-methyl-5-hexylfuran 5 in a Wolff-Kishner reduction using hydrazine. An acid-catalyzed reaction at 120 °C (248 °F) cleaves the furan ring, producing 2,5-undecanedione 6.[1]
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An alternative route of synthesis starts with heptanal 1. First, the carbonyl group is protected with 1,3-propanedithiol 2, producing a dithiane 3. The dithiane is deprotonated using n-Butyllithium in tetrahydrofuran, and alkylated using 1,3-dichloro-2-butene 4 to give the intermediate 5. Hydrolysis of the dithioacetal protecting group with concentrated sulfuric acid yields 2,5-undecanedione 6, which can be worked up and purified using Girard's reagent T[2] in methanol.[3]
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Uses
2,5-Undecanedione is used in the Hunsdiecker condensation (de), a reaction developed by Heinz Hunsdiecker in 1942 to produce cyclopentenones from γ-ketones, in sodium hydroxide solution to produce the fragrance dihydrojasmone:[1]
References
- ↑ 1.0 1.1 Heinz Hunsdiecker (1942-05-06), "Über das Verhalten der γ-Diketone, I. Mitteilung", Berichte der Deutschen Chemischen Gesellschaft 75 (5): 447–454, doi:10.1002/cber.19420750502
- ↑ PubChem. "Girard's reagent T" (in en). https://pubchem.ncbi.nlm.nih.gov/compound/67156.
- ↑ Ho, Tse-Lok; Ho, Honor C.; Wong, C. M. (1973-01-15). "A Synthetic Route to Dihydrojasmone; Sulfuric Acid as Dethioacetalization Agent" (in en). Canadian Journal of Chemistry 51 (2): 153–155. doi:10.1139/v73-023. ISSN 0008-4042. http://www.nrcresearchpress.com/doi/10.1139/v73-023.
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