Enantiomeric Purity and Odor Characteristics of 2- and 3-Acetoxy-1,8-cineoles in the Rhizomes of <i>Alpinia </i><i>g</i><i>alanga</i> Willd.
作者:Kikue Kubota、Yuki Someya、Reiko Yoshida、Akio Kobayashi、Tetsu-ichiro Morita、Hiroyuki Koshino
DOI:10.1021/jf9807465
日期:1999.2.1
(S)-(+)-O-methylmandelate esters of trans- and cis-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-5- and 6-ols (2- and 3-hydroxy-1,8-cineoles) were prepared, and eight diastereomers were separated. The absolute configuration of the asymmetric carbons of the cineole moiety of each diastereomer was determined by H-1 NMR data according to the Mosher theory. Each mandelate was reduced with LiAlHe4 to obtain optically pure hydroxy-1,8-cineoles, this being followed by acetylation to afford optically pure acetoxy-1,8-cineoles. These acetates were subjected to chiral GC, using a cyclodextrin column, and the enantiomeric purity of trans- and cis-1,3,3-trimethyl-2-oxabicyclo[2.2.2]octan-5- and 6-yl acetates in the aroma concentrate from the rhizomes of Alpinia galanga was determined as 93.9 (5S), 19.4 (5R), 63.5 (6R), and 100 (6R) % cc, respectively. The aroma character of each enantiomer was also evaluated by GC-sniffing.