Determination of the Configuration of Wine Lactone

The intense sweet and coconut‐like smelling odorant 1 , named ‘wine lactone’, was isolated from different wine varieties. The chemical structure of this compound, which has not yet been detected in wine or a food, was identified by high‐resolution mass spectrometry (HR‐MS) as 3a,4,5,7a‐tetrahydro‐3,6‐dimethylbenzofuran‐2(3 H )‐one. For the evaluation of the configuration of wine lactone, stereochemically controlled syntheses were developed. All eight isomers were characterized by NMR, MS, IR, and CD measurements. The configuration of ‘wine lactone’ was in agreement with synthesized (3 S ,3a S ,7a R )‐enantiomer ( 1a ) on the basis of enantioselective GC. For this isomer, the lowest odor threshold (0.02 pg/1 air) was detected.