Photogreen Lab, Department of Chemistry, University of Pavia , V. Le Taramelli 12, 27100 Pavia, Italy.
J Am Chem Soc. 2014 Oct 1;136(39):13874-81. doi: 10.1021/ja507735u. Epub 2014 Sep 18.
The photoreactivity of differently substituted (chloromethoxybenzyl)trimethylsilanes in alcohols and alcohol/water mixtures has been investigated by means of a combined computational and experimental approach. Subsequent elimination of the chloride anion and the trimethylsilyl cation gives the corresponding methoxy-substituted α,n-didehydrotoluenes (α,n-MeO-DHTs). The rate of desilylation is evaluated through the competition with arylation via phenyl cation (ca. 10(8) s(-1)). α,2-MeO- and α,4-MeO-DHTs show a purely radical behavior (H abstraction from the solvent, methanol), while α,3-MeO-DHT shows mainly a ionic chemistry, as when the parent α,3-DHT is thermally generated. This is likely due to triplet-singlet surfaces crossing occurring during desilylation.
通过计算和实验相结合的方法，研究了不同取代的（氯甲氧基苄基）三甲基硅烷在醇和醇/水混合物中的光反应性。随后消除氯离子和三甲基硅阳离子，得到相应的甲氧基取代的α,n-去氢甲苯（α,n-MeO-DHTs）。通过与芳基阳离子（约 10(8) s(-1))的芳基化竞争来评估脱硅反应的速率。α,2-MeO-和α,4-MeO-DHTs 表现出纯粹的自由基行为（从溶剂甲醇中提取氢），而α,3-MeO-DHT 主要表现出离子化学行为，就像母体α,3-DHT 被热生成时一样。这可能是由于在脱硅过程中发生了三重态-单重态表面交叉。
