Rotational isomerism involving an acetylenic carbon<scp>iv</scp>: synthesis and structure of bis(1,1′;3′,1″-terphenyl-2′-yl)ethynes: molecular design of sterically congested alkynes toward restricted rotation about acetylenic axis.
作者:Shinji Toyota、Taku Iida、Chinatsu Kunizane、Naoki Tanifuji、Yukihiro Yoshida
DOI:10.1039/b302016a
日期:——
between the tolyl groups. The relative stabilities of possible conformers were analyzed by the PM3 calculations. The axially chiral derivative with two methoxymethyl groups showed no evidence of restricted rotation about the acetylenic axis by VT NMR measurements, its barrier being less than 35 kJ mol(-1). The spectroscopic features and reactivities of this sterically congested alkyne are also described
通过Stille或Sonogashira偶联从相应的碘化物合成在所有邻位具有4-甲基苯基(甲苯基)基团的标题二苯基乙炔衍生物。X-射线结构揭示了sp碳上的两个末端苯基基团在共面构象之外扭曲了63度,从而避免了甲苯基之间的空间相互作用。通过PM3计算分析可能的构象异构体的相对稳定性。带有两个甲氧基甲基的轴向手性衍生物通过VT NMR测量没有显示出绕乙炔轴旋转受限的证据,其势垒小于35 kJ mol(-1)。还描述了这种空间拥挤的炔烃的光谱特征和反应性。