Investigation on the Reactions of Small Ring Ion Radicals and their Application to Synthetic Reactions

1. 三个氘标记和烷基取代的双环[2.2.0]己烷的光敏单电子氧化产生了主要保留构型的1,5-己二烯，这表明中间环己烷-1,4-二基阳离子自由基在船形构象中发生了环裂解，而船形构象被相当大的能量势垒与椅形构象和/或扭形构象分开。环裂变的立体专一性取决于电子受体的还原电位，这意味着自由基离子对中的环裂解和反向电子转移在速率上是竞争的。合成了4-Thiadispiro[2.1.2.2]非8-烯和几种螺环丙基芴，并测定了它们对缺电子化合物的反应性。前一种化合物与TCNQ和TCNE进行环加成，其中以太溶剂的使用至关重要，并获得噻吩衍生物。研究了几种1,4桥杜瓦苯衍生物在光敏单电子氧化条件下的行为。它们经历了中心sigma键的裂解，得到亲核试剂加入的弯曲苯阳离子自由基。在研究过程中，我们还成功地合成了弯曲度最高的苯衍生物-[4]对环己烷，一种新型的全共轭双环体系-双环[4.2.2]十戊烯，以及邻喹啉衍生物-3,4-苯并托酮。

1. The photosensitized one electron oxidation of three deuterium-labeled and alkyl substituted bicyclo[2.2.0]hexanes afforded 1,5-hexadienes predominantly with the retention of configuration, which indicated that intermediate cyclohexane-1,4-diyl cation radicals underwent ring cleavage in the boat conformation which was separated from the chair and/or twist-boat conformation by a sizable energy barrier. The dependence of the stereospecificity of ring fission on the reduction potential of electron acceptor implied that the ring cleavage and back electron transfer in the radical ion pairs were competitive in rate.2. 4-Thiadispiro[2.1.2.2]non-8-ene and several spiro-cyclopropylfluorenes were synthesized and their reactivities toward electron deficient compounds were examined. The former compound underwent cycloadditions with TCNQ and TCNE in which the use of ethereal solvent was critical and afforded thiophenophane derivatives.3. The behavior of some 1,4-bridged Dewar benzene derivatives under the conditions of photosensitized one electron oxidation was studied. They underwent the cleavage of central sigma bond to give bent benzene cation radicals to which nucleophiles added. In the process of study, we also succeeded in generating the most highly bent benzene derivative-[4]paracyclophane, a novel, fully conjugated bicyclic system-bicyclo[4.2.2]decapentaene, and an ortho quinoidal tropone derivative-3,4-benzotropone.