Dai Yifeng, Shao Junqiang, Yang Shaoxiang, Sun Baoguo, Liu Yongguo, Ning Ting, Tian Hongyu
School of Food Chemistry, Beijing Key Laboratory of Flavor Chemistry, Beijing Technology and Business University , Beijing 100048, China.
J Agric Food Chem. 2015 Jan 21;63(2):464-8. doi: 10.1021/jf503866x. Epub 2015 Jan 9.
The enantioselective synthesis of four stereoisomers of 2-methyl-tetrahydrofuran-3-thiol acetate was achieved. The two enantiomers of the important intermediate cis-2-methyl-3-hydroxy-tetrahydrofuran were obtained by Sharpless asymmetric dihydroxylation (AD), whereas the two enantiomers of trans-2-methyl-3-hydroxy-tetrahydrofuran were derived from the corresponding optically active cis-isomers by Mitsunobu reaction. Each stereoisomer of 2-methyl-3-hydroxy-tetrahydrofuran went through mesylation and nucleophilic substitution to afford the corresponding product with specific configuration. (2R,3S)- and (2R,3R)-2-methyl-tetrahydrofuran-3-thiol acetate were obtained in 80% ee, whereas the (2S,3R)- and (2S,3S)-isomers were in 62% ee. The odor properties of the synthesized four stereoisomers were evaluated by gas chromatography-olfactometry (GC-O), which revealed perceptible differences among stereoisomers both in odor features and in intensities.
实现了2-甲基-四氢呋喃-3-硫醇乙酸酯四种立体异构体的对映选择性合成。重要中间体顺式-2-甲基-3-羟基-四氢呋喃的两种对映体通过夏普莱斯不对称双羟基化反应（AD）获得，而反式-2-甲基-3-羟基-四氢呋喃的两种对映体则通过 Mitsunobu 反应从相应的旋光性顺式异构体衍生而来。2-甲基-3-羟基-四氢呋喃的每种立体异构体经过甲磺酰化和亲核取代反应，得到具有特定构型的相应产物。(2R,3S)-和(2R,3R)-2-甲基-四氢呋喃-3-硫醇乙酸酯的对映体过量百分数（ee）为80%，而(2S,3R)-和(2S,3S)-异构体的ee为62%。通过气相色谱-嗅觉测量法（GC-O）对合成的四种立体异构体的气味特性进行了评估，结果表明立体异构体在气味特征和强度方面均存在明显差异。
