Trans-3-Methyl-4-octanolide explained

trans-3-Methyl-4-octanolide, also called trans-β-methyl-γ-octalactone is a chemical compound of the lactone family with formula . It exists in two stereoisomers: (3R,4S) and (3S,4R).

The (3S,4R) form is found in whiskey and other alcoholic beverages that have been aged in oak barrels, together with the more important cis isomer.^{[1] [2]} It has a coconut, celery or fresh wood aroma, that can be detected by humans at the concentration of 20 μg/L in air.^[3] A mixture of the cis and trans isomers is repellent for mosquitos and flies.^[4]

The (3S,4R) isomer is extracted by the alcoholic beverage from some precursor substances in the oak wood.^[5] It can be synthesized in various ways.^{[3] [6] [7]}

See also

• cis-3-Methyl-4-octanolide, the more important stereoisomer

Notes and References

1. Web site: Aromas and Flavours . Wine-Pages.com . 2007-12-18 . dead . https://web.archive.org/web/20071018025957/http://www.wine-pages.com/guests/tom/taste5.htm . 2007-10-18 .
2. Hans-Dieter Belitz, Peter Schieberle, and Werner Grosch (2004) Food Chemistry, page 383. Springer,
3. 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
4. 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
5. Masuda and Nishimura (1971), Branched nonalactones from some Quercus species. Phytochemistry, volume 10, pages 1401-1402.
6. Hisashi Nishikori, Katsuji Ito, and Tsutomu Katsuki (1998) A short-step synthesis of trans-whisky lactone by an asymmetric Michael reaction. Tetrahedron: Asymmetry, volume 9, pages 1165–1170.
7. Katsuji Ito, Miwa Yoshitake and Tsutomu Katsuki (1995), Enantioselective Synthesis of trans-Whisky Lactone by Using Newly Developed Asymmetric Ring Expansion Reaction of Oxetane as a Key Step. Chemistry Letters, volume 24, issue 11, page 1027