Laboratory of Asymmetric Catalysis and Synthesis, EPFL SB ISIC LCSA, BCH 4305, 1015 Lausanne (Switzerland) http://isic.epfl.ch/lcsa.
Angew Chem Int Ed Engl. 2014 Mar 24;53(13):3484-7. doi: 10.1002/anie.201310723. Epub 2014 Feb 19.
Larger condensed arenes are of interest owing to their electro- and photochemical properties. An efficient synthesis is the catalyzed aromatic annulation of a smaller arene with two alkyne molecules. Besides difunctionalized starting materials, directed C-H functionalization can be used for such aromatic homologation. However, thus far the requirement of either pre-functionalized substrates or suitable directing groups were limiting this approach. Herein, we describe a rhodium(III)-catalyzed method allowing the use of completely unbiased arenes and internal alkynes. The reaction works best with copper(II) 2-ethylhexanoate and decabromodiphenyl ether as the oxidant combination. This aromatic annulation tolerates a variety of functional groups and delivers homologated condensed arenes. Aside from simple benzenes, naphthalenes and higher condensed arenes provide access to highly substituted and highly soluble acenes structures having important electronic and photophysical properties.
大的稠环芳烃因其电化学和光化学性质而受到关注。一种有效的合成方法是催化较小的芳烃与两个炔烃分子的芳香环化反应。除了双官能化的起始原料外，定向 C-H 官能化也可用于这种芳香同系化。然而，到目前为止，对预官能化的底物或合适的导向基团的要求限制了这种方法。在此，我们描述了一种铑(III)催化的方法，允许使用完全无偏见的芳烃和内部炔烃。该反应在铜(II) 2-乙基己酸酯和十溴二苯醚作为氧化剂组合时效果最佳。这种芳香环化反应可以容忍各种官能团，并提供同系化的稠环芳烃。除了简单的苯外，萘和更高的稠环芳烃可以获得具有重要电子和光物理性质的高度取代和高溶性并苯结构。
