(-)-(4S,4aS,8aR)-Geosmin - earthy-musty. The (-) enantiomer is much more odoriferous than the (+) form. The (-)-enantiomer is the one found in nature. Odor threshold = 0.0082- 0.018 ppb (in water) Also known as (-)-(4S,4aS,8aR)-4,8a-Dimethyl-octahydronaphthalen-4a-ol and as (-)-trans-1S,10R-Dimethyl-trans-9S-decalol. Ref: Philippe Darriet, Sophie Lamy, Stephane La Guerche, Monique Pons, Denis Dubourdieu, Dominique Blancard, Panagiotis Steliopoulos and Armin Mosandl, Stereodifferentiation of geosmin in wine, Eur. Food Res. Technol. (2001) 213: 122-125; For a stereospecific synthesis of (+)- and (-)-geosmin, see: Gilbert Revial, Asymmetric Michael-type alkylation of chiral imines. Enantioselective syntheses of (-)-geosmin and two other related natural terpenes, as well as enant-(+)-geosmin, Tetrahedron Letters, Volume 30, Issue 31, 1989, Pages 4121-4124 Odor threshold values given are from Polak, E. H.; Provasi, J., Odor sensitivity of geosmin enantiomers, Chem. Senses 1992, 17, 23-26. It should be noted that reported threshold values for geosmin range from 0.002 - 360 ppb in the literature (L.J. van Gemart, Compilations of odour threshold values in air and water, Boelens Aroma Chemical Information Service, Publisher, 1999, Water Section p. 27).

(+)-(4R,4aR,8aS)-Geosmin - earthy-musty. The (-) enantiomer is much more odoriferous than the (+) form Odor threshold = 0.066-0.090 ppb (in water) Also known as (+)-(4R,4aR,8aS)-4,8a-Dimethyl-octahydronaphthalen-4a-ol and as (-)-trans-1R,10S-Dimethyl-trans-9R-decalol. Ref: Philippe Darriet, Sophie Lamy, Stephane La Guerche, Monique Pons, Denis Dubourdieu, Dominique Blancard, Panagiotis Steliopoulos and Armin Mosandl, Stereodifferentiation of geosmin in wine, Eur. Food Res. Technol. (2001) 213: 122-125; For a stereospecific synthesis of (+)- and (-)-geosmin, see: Gilbert Revial, Asymmetric Michael-type alkylation of chiral imines. Enantioselective syntheses of (-)-geosmin and two other related natural terpenes, as well as enant-(+)-geosmin, Tetrahedron Letters, Volume 30, Issue 31, 1989, Pages 4121-4124 Odor threshold values given are from Polak, E. H.; Provasi, J., Odor sensitivity of geosmin enantiomers, Chem. Senses 1992, 17, 23-26. It should be noted that reported threshold values for geosmin range from 0.002 - 360 ppb in the literature (L.J. van Gemart, Compilations of odour threshold values in air and water, Boelens Aroma Chemical Information Service, Publisher, 1999, Water Section p. 27).

Ionones, Irones, Damascones & Structurally Related Odorants

Acyclics (Alcohols, Esters, Acids, Aldehydes)

Lactones

Sesquiterpenoid Related Odorants