6S,8R-Stereochemistry of the C27- and C29-Alkane-6,8-diols Isolated from Three Compositae Flowers.
作者:Motohiko UKIYA、Toshihiro AKIHISA、Shigeyasu MOTOHASHI、Ken YASUKAWA、Yumiko KIMURA、Yoshimasa KASAHARA、Michio TAKIDO、Norio TOKUTAKE
DOI:10.1248/cpb.48.1187
日期:——
The Δδ(δS-δR) values for the C-1 methyl 1H signals in the 1H-NMR spectroscopy of the bis-MTPA esters of four synthetic stereoisomers of alkane-6, 8-diols, viz., bis-MTPA esters of (6S, 8R)-C27- (1a) and C29- (3a) (Δδ=-0.05 ppm), (6R, 8S)-C27- (2a) and C29- (4a) (Δδ=+0.05 ppm), (6S, 8S)-C27- (5a) (Δδ=-0.01 ppm), and (6R, 8R)-C27- (6a) (Δδ=+0.01 ppm) alkane-6, 8-diols, made it possible to differentiate unequivocally among the four stereoisomers. This allowed the determination of the (6S, 8R)-stereochemistry (Δδ=-0.05 ppm for the bis-MTPA esters) for the natural C27- and C29-alkane-6, 8-diols isolated from the flowers of three Compositae plants, Carthamus tinctorius, Cynara cardanclus, and Taraxacum platycarpum.
四种烷-6、8-二醇的合成立体异构体的双-MTPA 酯(即:(6S, 8R)-C27- (1a) 和 C29- (3a) 的双-MTPA 酯)的 1H-NMR 光谱中 C-1 甲基 1H 信号的 Δδ(δS-δR) 值(Δδ=-0.05 ppm,6R, 8S)、(6S, 8R)-C27- (1a) 和 C29- (3a) (Δδ=-0.05 ppm)、(6R, 8S)-C27- (2a) 和 C29- (4a) (Δδ=+0.05 ppm)、(6S, 8S)-C27- (5a) (Δδ=-0.01ppm)和 (6R, 8R)-C27- (6a) (Δδ=+0.01ppm)烷-6,8-二醇,这使得明确区分四种立体异构体成为可能。这样就可以确定从三种菊科植物(Carthamus tinctorius、Cynara cardanclus 和 Taraxacum platycarpum)的花中分离出来的天然 C27- 和 C29- 烷-6,8-二醇的 (6S,8R) 立体化学结构(双-MTPA 酯的Δδ=-0.05 ppm)。