Bhunia Samir Kumar, Polley Arghya, Natarajan Ramalingam, Jana Ranjan
Organic and Medicinal Chemistry Division, CSIR-Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032 (India), Fax: (+91) 33-2473-5197.
Academy of Scientific and Innovative Research-Kolkata, 4 Raja S. C. Mullick Road, Jadavpur, Kolkata 700032 (India).
Chemistry. 2015 Nov 16;21(47):16786-91. doi: 10.1002/chem.201503474. Epub 2015 Oct 6.
A palladium-catalyzed expeditious synthesis of dibenzofused carbazoles from readily available 2-arylindoles and diaryliodonium salts is reported. Interestingly, after the electrophilic C3 palladation of indole, an unexpected "through-space" 1,4-palladium migration to the 2-aryl moiety, by remote C-H bond activation followed by C-H arylation with diaryliodonium salt, and an unprecedented 1,2-aryl shift take place. Finally, an intramolecular cross-dehydrogenative coupling (CDC) at the C2 position affords dibenzo[a,c]carbazoles in high yields. Remarkably, the present migratory annulation occurs through three C-H bond activation one C-C bond cleavage, and the simultaneous construction of three new C-C bonds in a single operation.
报道了一种由易于获得的2-芳基吲哚和二芳基碘鎓盐通过钯催化快速合成二苯并稠合咔唑的方法。有趣的是，在吲哚的亲电C3钯化之后，发生了意想不到的“空间穿越”1,4-钯迁移至2-芳基部分，这是通过远程C-H键活化，随后与二芳基碘鎓盐进行C-H芳基化反应，并发生了前所未有的1,2-芳基迁移。最后，在C2位置进行分子内交叉脱氢偶联（CDC）反应，以高产率得到二苯并[a,c]咔唑。值得注意的是，目前的迁移环化反应通过三次C-H键活化、一次C-C键断裂，并在单一操作中同时构建三个新的C-C键。
