experimental observations to show atropisomerism. Energy barrier for the inversion of pentathiepin ring was experimentally determined by variable temperature 1H NMR. The kinetic data suggested that pentathiepin ring inversion was prompt in solution. Insufficient rotational energy barriers of chiral axis and pentathiepin ring inversion make substantially impossible to separate optically pure diastereomer
通过二硫杂锡的硫化反应在联芳基上合成了新型的轴向手性苯并多硫化物。在1,1'-联芳基上观察到五硫平,三硫醇和三硫醇2-氧化物环为单一异构体。通过在邻位引入甲基增加了手性轴的旋转能垒。在这种情况下,三硫醇氧化物环和五环素环都以非对映异构体的形式出现。邻位-甲苯基官能团也被萘基部分取代,以产生更多的旋转障碍。Suzuki-Miyaura交叉偶联反应将手性轴并入多硫化物官能团附近。计算得出的旋转能垒与实验观察结果非常吻合,以显示阻转异构现象。通过可变温度1 H NMR实验确定了五硫平环倒置的能垒。动力学数据表明,戊硫平环的倒置在溶液中是迅速的。手性轴的旋转能垒和戊二烯环反转不充分,即使通过手性色谱分离也基本上不可能分离出光学纯的非对映异构体。哦,H。山本T。中仲,S .; 小川 阿拉姆四面体Lett。2007年,48,4991-4994。]。
Synthesis of novel axially chiral cyclic benzopolysulfides
作者:Ryu Sato、Hidetoshi Ohta、Tatsuya Yamamoto、Shiduko Nakajo、Satoshi Ogawa、Ashraful Alam
DOI:10.1016/j.tetlet.2007.05.117
日期:2007.7
synthesized by sulfurization of dithiastannole. Naphthyl moiety was introduced near the pentathiepin ring by Suzuki–Miyaura cross-coupling reaction. Pentathiepins were found as diastereomeric mixture. Rotational energy barrier for C–C bond was estimated by theoretical calculation. Energy barrier for the inversion of pentathiepin ring was experimentally determined by variable temperature 1H NMR.
通过二硫杂锡的硫化合成了新型的轴向手性苯并五硫平。萘基部分通过Suzuki-Miyaura交叉偶联反应引入到五硫平环附近。发现五肽是非对映异构体混合物。通过理论计算可以估算出C–C键的旋转能垒。通过可变温度1 H NMR实验确定了五硫平环倒置的能垒。