Contrastive Photoreduction Pathways of Benzophenones Governed by Regiospecific Deprotonation of Imidazoline Radical Cations and Additive Effects
作者:Eietsu Hasegawa、Takayuki Seida、Naoki Chiba、Tomoya Takahashi、Hiroshi Ikeda
DOI:10.1021/jo0514220
日期:2005.11.1
In the photoreaction of benzophenones with 1,3-dimethyl-2-phenylbenzimidazoline (DMPBI), benzhydrols were major products. Addition of H2O accelerated the reaction with no change in the product distribution, while AcOH, PhOH, and metal salts such as LiClO4 and Mg(ClO4)2 were effective additives to produce benzpinacols. In contrast, benzpinacols were exclusively formed regardless of the solvent and the
在二苯甲酮与1,3-二甲基-2-苯基苯并咪唑啉(DMPBI)的光反应中,苯甲醇是主要产物。H 2 O的添加加速了反应,产物分布没有变化,而AcOH,PhOH和金属盐(如LiClO 4和Mg(ClO 4)2)是生产苯并人醇的有效添加剂。相反,在与2-(邻-羟基苯基)-1,3-二甲基苯并咪唑啉(邻-HPDMBI)的反应中,无论溶剂和添加剂如何,仅形成苯并二十烷醇。这些观察结果与DMPBI • +在C 2上提供质子的假设相符。位置的二苯甲酮羰自由基而Ø -HPDMBI •+捐赠苯酚质子。