Tetrahydro-dimethyl-benzofuranone

A very important lactone in wines is the so-called wine lactone," 3a,4,5,7a-tetrahydro-3,6-dimethyl-2(3H)-benzofuranone 5, which exists in four enantiomeric pairs. This compound was first identified and isolated from the urine of Koala bears (75TL1885, 97JAFC3027), from their diet of the leaves of the Eucalyptus punctata tree. And this shows that the wine lactone belongs to monoterpenoid flavoring ingredients, which have been converted into oxygenated forms. 

Synonyms Dehydroxymenthofurolactone 3,6-Dimethyl-5,6,7,7a-tetrahydro-2(4H)-benzofuranone Mintlactone... 

Fig. 5.12. Gas chromatogram of the diastereomers of 3a,4,5,7a-tetrahydro-3,6-dimethyl-2(3H)-benzofuranone (wine lactone) on a chiral phase (according to Guth, 1997)...

IR, 3R, 4S) which occurs in peppermint oil, has a clean sweet, cooling and refreshing peppermint aroma, while in the d-form (IS, 3S, 4R) it has remarkable, disagreeable notes such as phenolic, medicated, camphor and musty. Carvone (XXI in Table 5.33) in the R(—)-form has a peppermint odor. In the S(+)-form it has an aroma similar to caraway. Other examples that show the influence of stereochemistry on the odor threshold of terpenes are 3a,4,5,7a-tetrahydro-3,6-dimethyl-2(3H)-benzofuranone (cf. 5.2.5) and 1-p-menthene-8-thiol (cf. 5.3.2.5). 

---