Polukhtine Andrei, Karpov Grigori, Popik Vladimir V
Department of Chemistry, University of Georgia, Athens, GA 30602, USA.
Curr Top Med Chem. 2008;8(6):460-9. doi: 10.2174/156802608783955700.
The concept of photoswitchable enediynes, which are stable in the dark but undergo efficient cycloaro-matization reaction to produce p-benzyne diradical after irradiation with light of an appropriate wavelength, is discussed. Two novel methods for the generation of reactive enediyne compounds from thermally stable precursors have been developed. In the first approach, one of the triple bonds of cyclodeca-3-ene-1,5-diynes is replaced with cyclopropenone group. Cyclopropenone-containing enediyne precursors are unable to undergo cycloaromatization because the enediyne fragment is incomplete. Photolysis of cyclopropenones results in the efficient decarbonylation and the regeneration of a triple bond thus completing the enediyne pi-system. The second method employs photo-Wolff reaction to achieve ring contraction of stable eleven-membered ring precursor enediynes. Benzannulated cyclic enediynes produced by the photodecomposition of enediyne precursor containing 2-diazo-1,3-diketones possess enolized beta-ketoester fragment and undergo remarkably facile tau(36)o = 5 min - 3 h) Bergman cyclization. The generation of reactive enediyne was also achieved with NIR light by non resonant two-photon excitation.
本文讨论了光开关烯二炔的概念，这类化合物在黑暗中稳定，但在适当波长的光照射后会发生高效的环化芳构化反应生成对苯撑双自由基。现已开发出两种从热稳定前体生成活性烯二炔化合物的新方法。在第一种方法中，环癸 - 3 - 烯 - 1,5 - 二炔的一个三键被环丙烯酮基团取代。含环丙烯酮的烯二炔前体无法进行环化芳构化，因为烯二炔片段不完整。环丙烯酮的光解导致高效脱羰并再生三键，从而完成烯二炔π体系。第二种方法采用光沃尔夫反应实现稳定的十一元环前体烯二炔的环收缩。由含2 - 重氮 - 1,3 - 二酮的烯二炔前体光分解产生的苯并环烯二炔具有烯醇化的β - 酮酯片段，并能非常容易地进行（τ(36)o = 5分钟 - 3小时）伯格曼环化反应。通过非共振双光子激发，利用近红外光也实现了活性烯二炔的生成。
