Rotational isomerism in 3,4-alkylenedioxy-2,5-bis[di(<i>tert</i>-butyl)hydroxymethyl]thiophenes>
作者:John S. Lomas、Christine Cordier
DOI:10.1002/poc.640
日期:2003.7
In 3,4-ethylenedioxy-2,5-bis[di(tert-butyl)hydroxymethyl]thiophene there are three rotational isomers, syn,syn (SS), anti,syn (AS) and anti,anti (AA) (syn, free; anti, hydrogen-bonded), differing in the number (zero, one or two) of alcohol hydrogen atoms intramolecularly hydrogen bonded to the oxygen atoms of the bridge. When a methyl group is introduced into the bridge the AS rotamer can be distinguished
在3,4-乙撑二氧基-2,5-双[二(叔丁基)羟甲基]噻吩中,存在三种旋转异构体,即syn,syn(SS),anti,syn(AS)和anti,anti(AA)(syn,游离;抗,氢键键合),其分子内氢键合到桥的氧原子上的醇氢原子数(零,一或两个)不同。当将甲基引入桥中时,可以将AS旋转异构体与SA区别开[其中第一个字符表示-C(t -Bu)2的方向OH基团更接近于取代基]通过1 H NOESY实验进行。带有氢键的溶剂倾向于带有“游离” OH基团的形式,但是甲基衍生物的AS:SA比值与溶剂无关,因此稍微有利于AS异构体。无论使用哪种溶剂,甲基均对平衡旋转异构体比率没有重大影响。各种平衡的旋转势垒约为20 kcal mol -1。版权所有©2003 John Wiley&Sons,Ltd.