Electron-transfer-induced photocyclization reactions of arene-iminium salt systems. Effects of cation-diradical deprotonation and desilylation on the nature and efficiencies of reaction pathways followed
作者:Alexander J. Y. Lan、Robert O. Heuckeroth、Patrick S. Mariano
DOI:10.1021/ja00243a029
日期:1987.4
The features of these photochemical processes whose chemical outcomes are dependent upon the nature of reaction pathways available to cation diradical intermediates are discussed. Finally, the photoinduced, diradical cyclization methodology for transformation of the silicon-containing N-xylylpyrrolinium perchlorates 4 and 6 has been compared to the alternative dipolar pathway promoted by fluoride-induced
N-xylyl-1-pyrrolinium perchlorate 3-6 由激发态电子转移引起的光环化反应已被探索,目的是揭示机械细节并开发合成应用。硅取代的盐 4 和 6 都经过光环化以产生各自的苯并吲哚里西啶产物 30 和 13,完全通过涉及顺序电子转移-脱甲硅烷基化的机制。另一方面,不含硅的 2-苯基-1-吡咯啉高氯酸盐 5 在辐照时会转化为吲哚里西啶 13 和 2-苯基-1-吡咯啉 (10)。建议通过中间双自由基阳离子 14 的裂解产生光碎裂生成 10,这与去质子化和 1,6-双自由基偶联竞争形成 13。最后,当2-甲基-N-二甲苯基-和2-甲基-N-苄基吡咯啉鎓高氯酸盐3和21被辐照时,产生苯并吡咯里西啶22和23。氘标记研究表明,这些光环化反应通过双自由基阳离子偶联过程进行。讨论了这些光化学过程的特征,其化学结果取决于可用于阳离子双自由基中间体的反应途径的性质。最后,将用于转化含硅