Cis-3-Methyl-4-octanolide explained

cis-3-Methyl-4-octanolide, also called cis-β-methyl-γ-octalactone or 5-butyldihydro-4-methylfuran-2(3H)-one, is a chemical compound of the lactone family with formula . It exists in two optical isomers: 3R,4R ("+") and 3S,4S ("−").

The 3S,4S isomer, commonly known as whisky lactone or quercus lactone is an important ingredient in the aroma of whiskey (where it was first identified by Suomalainen and Nykänen in 1970) and other alcoholic beverages that have been aged in oak barrels. It is sometimes added to the liquor as a flavoring agent.^{[1] [2] [3] [4]} It has a coconut, celery or fresh wood aroma, that can be detected by humans at the concentration of 1 μg/L in air.^[5] A mixture of the cis and trans isomers is repellent for mosquitos and flies.

The 3S,4S isomer is extracted by the alcoholic beverage from some precursor substances in the oak wood.^{[5] [6] [7]} It can be synthesized from a cyclopentane derivative.^[8]

See also

• trans-3-Methyl-4-octanolide, a stereoisomer also found in oak-aged beverages.

Notes and References

1. NITS Material Measurement Laboratory, Cis-3-methyl-4-octanolide. Accessed on 2011-01-02.
2. Web site: Aromas and Flavours . Wine-Pages.com . 2007-12-18 . https://web.archive.org/web/20071018025957/http://www.wine-pages.com/guests/tom/taste5.htm . 2007-10-18 . dead .
3. Hans-Dieter Belitz, Peter Schieberle, and Werner Grosch (2004) Food Chemistry, page 383. Springer,
4. LECO Corporation, Qualitative Comparison of Whisky Samples Using Fast GC/TOFMS . Accessed on 2011-01-02.
5. Eric Masson, Raymond Baumes, Christine Le Guernevé, and Jean-Louis Puech (2000) Identification of a Precursor of β-Methyl-γ-octalactone in the Wood of Sessile Oak (Quercus petraea (Matt.) Liebl.). J. Agric. Food Chem. volume 48, pages 4306-4309
6. Masuda and Nishimura (1971), Branched nonalactones from some Quercus species. Phytochemistry, volume 10, pages 1401-1402.
7. Takashi Tanaka and Isao Kouno (1996), Whisky Lactone Precursors from the Wood of Platycarya strobilacea. Journal of Natural Products, volume 59, pages 997-999.
8. Yukio Suzuki, Wakako Mori, Hiroyuki Ishizone, Koichi Naito, and Toshio Honda (1992) Concise Enantiospecific Syntheses of (+)-Eldanolide and (−)-cis-Whisky Lactone. Tetrahedron letters, volume 33, pages 4931-4932