180624-10-6Relevant articles and documents
Revisiting the Gold-Catalyzed Dimerization of 2-Ethynylanilines: A Room-Temperature and Silver-Free Protocol for the Synthesis of Multifunctional Quinolines
Praveen, Chandrasekar,Perumal
, p. 855 - 864 (2016/03/15)
A room temperature and silver-free protocol for the formation of quinolines from 2-ethynylanilines through a dimerization event was achieved using a dinuclear gold catalyst, Au2(BIPHEP)(NTf2)2. The reaction is inherently modular, allowing for the incorporation of peripheral substituents at any site of the quinoline product. The reaction is readily applied to other heterocyles also as exemplified by the preparation of naphthyridines. Competition reactions to determine the reactivity of dissimilar alkynes demonstrated that the product ratio of dimerization vs intermolecular addition is rather dependent on the electronic nature of aryl substituent on the alkynes. However, control experiments with substrates possessing internal alkynes resulted in cycloisomerization instead of expected dimerization, which is indicative of possible steric influence of the alkyne terminus in the reaction outcome.
Efficient reagents for the synthesis of 5-, 7-, and 5,7-substituted indoles starting from aromatic amines: Scope and limitations
Ezquerra, Jesus,Pedregal, Concepcion,Lamas, Carlos,Barluenga, Jose,Perez, Marta,Garcia-Martin, Miguel Angel,Gonzalez, Jose M.
, p. 5804 - 5812 (2007/10/03)
Upon reaction with IPy2BF4, 4-substituted anilines give regioselectively the corresponding o-iodoanilines in nearly quantitative yield, in a process that can be carried out on a multigram scale. Palladium-catalyzed coupling of the resulting 2-iodoanilines with (trimethylsilyl)acetylene (TMSA), followed by efficient CuI-mediated nitrogen cyclization onto alkynes with concurrent elimination of the TMS substituent, allows a straightforward elaboration of 5-mono- and 5,7-disubstituted indoles from aromatic amines. This new approach to the aforementioned indoles does not requires protective groups on nitrogen at any step and can be adapted for preparing related 7-monosubstituted indoles. Moreover, examples iterating the process are given, allowing bis-annulation and sequential double annulation and resulting in synthesis of benzodipyrroles. Additionally, suitable conditions for iodination of some of the target indoles with IPy2BF4 are discussed.
