Synthesis and characteristic odour of optically active 3‐hydroxy‐4‐phenyl‐2‐butanone

Enantioselective syntheses of two stereoisomers of 3‐hydroxy‐4‐phenyl‐2‐butanone were investigated via Shi's asymmetric epoxidation or Sharpless asymmetric dihydroxylation of silyl enol ether. ( R )‐3‐Hydroxy‐4‐phenyl‐2‐butanone was obtained in 73% enantiomeric excess ( ee ) by Shi's catalyst/oxone and 80% ee by AD‐mix‐β, while the ( S )‐isomer was prepared in 62% ee by AD‐mix‐α. The characteristic odour of the optically active products was analysed by gas chromatography–olfactometry. The ( R )‐isomer had a relatively weak fruity and green odour, while the ( S )‐isomer had a strong caramel, sweet and floral aroma. Additionally, the ( S )‐isomer presented a stronger odour intensity than did the ( R )‐isomer. Copyright © 2011 John Wiley & Sons, Ltd.