Boron as a Powerful Reductant: Synthesis of a Stable Boron‐Centered Radical‐Anion Radical‐Cation Pair
作者:Philipp Bissinger、Holger Braunschweig、Alexander Damme、Christian Hörl、Ivo Krummenacher、Thomas Kupfer
DOI:10.1002/anie.201409513
日期:2015.1.2
importance of radical‐anion radical‐cation pairs in single‐electron transfer (SET) reactions, such species are still very rare and transient in nature. Since diborenes have highly electron‐rich BB double bonds, which makes them strong neutral reductants, we envisaged a possible realization of a boron‐centered radical‐anion radical‐cation pair by SET from a diborene to a borole species, which are known
尽管自由基-阴离子自由基-阳离子对在单电子转移(SET)反应中具有根本的重要性,但这类物种在自然界中仍然非常罕见和短暂。由于diborenes具有富电子高度乙乙双键,这使得它们强烈中性还原剂,我们设想的可能实现一个以硼为中心的自由基阴离子自由基阳离子对由SET从diborene到borole物种,这是众所周知在单电子还原时形成稳定的自由基阴离子。但是,由于所有已知二硼烯的还原电势(E 1/2 = -1.05 / -1.55 V)的负电势不足以还原MesBC 4 Ph 4(E 1/2 = -1.69 V),因此合适的二硼烯I iPr⋅(我PR)BB(我PR)⋅I我PR,是度身订造,以符合这些要求。该二硼烯的半波电势为E 1/2 = -1.95 V,是已知最强的中性有机还原剂,可通过SET与MesBC 4 Ph 4反应,从而获得稳定的以硼为中心的自由基-阴离子自由基-阳离子对。