The effect of increased bulk of the beta-aryl group in enols Ar(2)C=C(OH)R from Ar = mesityl = Mes (1) to Ar = 2,4,6-i-Pr(3)C(6)H(2) = Tip (2) was investigated. The solid-state structure when R = H (a) does not significantly differ for 1a and 2a. The dynamic behavior of 2a resembles that of 1a, but the rotational barriers for both the threshold one-ring flip process and the two-ring flip process are
烯醇Ar(2)C = C(OH)R从Ar =均一= Mes(1)到Ar = 2,4,6-i-Pr(3)C( 6)H(2)=尖端(2)已研究。当R = H(a)时,固态结构对于1a和2a没有显着差异。2a的动态行为类似于1a,但是对于2a,阈值一环翻转过程和二环翻转过程的旋转势垒都更高。2a的单环翻转式屏障取决于溶剂。当R = Me(2b)和t-Bu(2c)时,阈值两环翻转势垒高于同位异构体,但2c的阈值高于预期。2a和1a的溶剂及其与
DMSO的关联相似。在非氢键接受溶剂中,C = COH构象与OH.pi(Tip)缔合为同平面,并且与OH呈反斜线。氢键接受溶剂中的溶剂缔合。总而言之,与变化Mes-> Tip相关联的增加的体积沿预期的方向改变了结构和行为,但是除了DeltaG(c)()值之外,在很大程度上没有变化。