A novel catalytic CâH activation route to privileged dibenzo[a,e]pentalene (DBP) structures has been established. In the presence of PdCl2, AgOTf, and o-chloranil, a CâH/CâH annulation of arylacetylenes takes place to furnish the corresponding DBPs. A number of mechanistic experiments indicate that this new annulation occurs through alkyne-directed, ortho-selective, electrophilic aromatic CâH palladation. Not only symmetric diarylacetylenes but also unsymmetric arylacetylenes are applicable to this reaction. UV-vis absorption spectra and DFT studies on the resulting DBPs indicate a strong substituent effect on the energy levels of the HOMO and HOMOâ1 of DBPs.
一种新的催化C–H活化路线已经建立,用于优越的二苯并[a,e]五烯(
DBP)结构。在PdCl2、AgOTf和邻
氯醌的存在下,芳基炔的C–H/C–H环化反应发生,从而生成相应的
DBP。多个机理实验表明,这种新的环化反应是通过
炔烃指导的邻位选择性电亲核芳香C–H
钯化发生的。不仅对称的二芳基炔,而且不对称的芳基炔也适用于该反应。对所得
DBP的紫外-可见吸收光谱和DFT研究表明,取代基对
DBP的HOMO和HOMO–1能级有强烈的取代效应。