Mammalian blood odorant and chirality: synthesis and sensory evaluation by humans and mice of the racemate and enantiomers of trans-4,5-epoxy-(E)-2-decenal

The racemate and enantiomers of trans-4,5-epoxy-(E)-2-decenal 1, an odorant with a metallic blood smell, were synthesized. The detection threshold for humans was 0.019 ppb for (2E,4S,5S)-(−)-1 and 0.62 ppb for (2E,4R,5R)-(+)-1, respectively. The racemate (±)-1 made mice scared stiff at a dosage of approximately 1 mg, while the enantiomers were not significantly bioactive.

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(2E,4R,5R)-trans-4,5-Epoxy-(E)-2-decenalC10H16O2ee 97.2% (chiral GC)[α]D24 = +26.2 (c 2.24, hexane)Source of chirality: Sharpless asymmetric epoxidation [(−)-DET]Absolute configuration: (4R,5R)