通常,空间正交轨道之间的远程电子通信效率低下,并且仅限于场和感应效应。在这项工作中,我们提供了实验证据,表明可以通过两个简并且相互正交的前沿分子轨道 (MO) 在过渡态的分子内电子转移来实现这种通信。当这些轨道之间的能隙接近零或“轨道交叉”时,正交轨道之间的相互作用被放大。两个空的或两个完全占据的 MO 之间的交叉不会导致稳定,当一个空的 MO 被填充(即电子注入)或填充的 MO 之一被减少(即空穴注入)时,可以“激活” )。在还原环芳构化反应中,这种交叉定义了具有由面内和面外 π 系统定义的能量的过渡态。在此,我们使用轨道交叉在烯二炔的还原性 C1-C5 环芳构化反应中为该概念的实用性提供了实验证据。与类似的自由基环化相比,通过轨道交叉与远程取代基的通信大大提高了闭环步骤的区域选择性。我们还提供了与电子注入苄基化烯二炔的效率有关的光物理数据。与类似的自由基环化相比,通过轨道交叉与远程取代
Complex Annulations through Silver Carbenoid Intermediate: An Alternative Entry to Transformations of 1,2,3-Triazoles
作者:Yuan Yang、Jiang-Xi Yu、Xuan-Hui Ouyang、Jin-Heng Li
DOI:10.1021/acs.orglett.7b01682
日期:2017.8.4
transformations of N-sulfonyl-4-(2-(ethynyl)aryl)-1,2,3-triazoles with various generated in situ or external nucleophiles by means of silver catalysis for producing diverse functionalized isoquinolines is described. Mechanistically, the reaction is proposed to involve a key silver carbenoid intermediate, thus enabling the formation of multiple chemical bonds via ring opening, N2 extrusion, silver carbenoid
aryldiyne derivatives with sulfonyl hydrazides in the presence of tetrabutylammonium iodide (TBAI) and tert-butyl hydroperoxide (TBHP) led to a cascade cyclization reaction to yield sulfonylated indeno[1,2-c]quinolines in moderate to good yields. The features of the methodology include metal-free reaction, the ease of reagent handling, and a broad functional group tolerance.
Copper-catalysed three-component carboiodination of arynes: expeditious synthesis of<i>o</i>-alkynyl aryl iodides
作者:Wenxuan Cao、Sheng-Li Niu、Li Shuai、Qing Xiao
DOI:10.1039/c9cc09160b
日期:——
A copper-catalysed three-component iodoalkynylation reaction of arynes for the expeditious and versatile synthesis of o-alkynyl aryl iodides has been developed. Mechanism research shows that the reaction goes through two steps enabled by copper catalysis: the formation of 1-iodo-2-arylacetylene and the insertion of the aryne into a C(sp)-I bond.
Photoactivated enediynes as targeted antitumoral agents: Efficient routes to antibody and gold nanoparticle conjugates
作者:Danielle Falcone、Jane Li、Amit Kale、Graham B. Jones
DOI:10.1016/j.bmcl.2007.12.045
日期:2008.2
Efficient syntheses of a series of functionalized aryl enediynes have been developed. The building blocks were used to effect conjugation to carrier PEG templates which allowed subsequent coupling to a cardiac targeted monoclonal antibody. Immunocompetence of the enediyne-Mab conjugates was demonstrated by ELISA, and both parent enediynes and bioconjugates underwent successful photo-Bergman cyclization
A fair exchange: In the title reaction, alkynyllithium serves as an initiator for benzyne generation through an iodine–lithium exchange (see scheme; Tf=trifluoromethanesulfonyl). When performed in the presence of stoichiometric amounts of a nucleophile, the generated benzyne undergoes attack by lithio nucleophiles to generate aryllithium, which is then iodinated by iodoalkyne to give the iodoarenes