Conformational studies by dynamic NMR.: 86.: Structure, stereodynamics, and cryogenic enantioseparation of the stereolabile isomers of o-dinaphthylphenyl derivatives
Conformational studies by dynamic NMR.: 86.: Structure, stereodynamics, and cryogenic enantioseparation of the stereolabile isomers of o-dinaphthylphenyl derivatives
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DOI：
10.1021/jo016397m
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发表时间：
2002-03-08
影响因子：
3.6
通讯作者：
Villani, C
中科院分区：
文献类型：
--
作者：
Dell-Erba, C;Gasparrini, F;Villani, C
包含在邻位带有两个α-萘基取代基的苯环的烃的静态和动态立体化学，即，1，2-二-（4-甲基-萘-1-基）-苯1已通过变温NMR、低温HPLC和MM计算的组合进行了研究。而在溶液中，观察到顺式（内消旋）和反式（手性）形式，并测定了相应的相互转化势垒（Δ G（双刃）= 19.5 kcal mol（-1）），只有非对映异构体反式被发现存在于结晶状态（X射线衍射）。当通过在苯环中引入硝基使分子不对称时，如在1，2-二-（4-甲基-萘-1-基）-4-硝基苯2中，手性顺式和反式非对映异构体同时存在于溶液和固态中，尽管比例不同。在-20 ℃下在HPLC手性固定相上的低温色谱法允许分离立体不稳定的非对映异构体和相应的对映异构体。
Static and dynamic stereochemistry of the hydrocarbon comprising a phenyl ring bearing two a-naphthyl substituents in the ortho positions, i.e., 1,2-di-(4-methyl-naphth-1-yl)-benzene 1, has been studied by a combination of variable temperature NMR, cryogenic HPLC, and MM calculations. Whereas in solution both syn (meso) and anti (chiral) forms were observed and the corresponding interconversion barrier was determined (DeltaG(double dagger) = 19.5 kcal mol(-1)), only the diastereoisomer anti was found to be present in the crystalline state (X-ray diffraction). When the molecule is rendered asymmetric by introduction of a nitro group in the phenyl ring as in 1,2-di-(4-methyl-naphth-1-yl)-4-nitrobenzene 2, the chiral syn and anti diastereoisomers are simultaneously present both in solution and in the solid state, albeit in different proportions. Cryogenic chromatography on a HPLC chiral stationary phase at -20 degreesC allowed the stereolabile diastereoisomers and the corresponding enantiomers to be separated.