6-Substituted-5H-pyrrolo[2,3-b]pyrazines via palladium-catalyzed heteroannulation from N-(3-chloropyrazin-2-yl)-methanesulfonamide and alkynes

Microwave-assisted, Copper-free Sonogashira Coupling Between Aryl Halides and Terminal Alkynes Using Recyclable Ionic Liquid and Catalyst

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An efficient method for the Sonogashira coupling reaction between aryl halides and terminal alkynes has been developed. The reaction was performed in ionic liquid 1-butyl-3- methylimidazolium tetrafluoroborate ([Bmim][BF4]) under microwave irradiation. High yields of products were obtained in a very short reaction time. Moreover, the medium and catalyst could be recovered and reused three times without considerable decrease in reaction yields.

Regioselective synthesis of dipyrrolopyrazine (DPP) derivatives via metal free and metal catalyzed amination and investigation of their optical and thermal properties

Pyrazine is an important molecular scaffold employed in organic optoelectronic materials.

2,6-Di(thiophenyl)-1,5-dihydrodipyrrolopyrazine (DT-DPP) structural isomers as donor–acceptor–donor molecules and their optoelectronic investigation

We report the synthesis and characterization of two new D–A–D molecules via Pd catalyzed C–C and C–N coupling reactions. This illustrates the potential of DT-DPP for promising optoelectronic applications.

Transition metal-catalyzed functionalization of pyrazines

Transition metal-catalyzed reactions are generally used for carbon-carbon bond formation on pyrazines and include, but are not limited to, classical palladium-catalyzed reactions like Sonogashira, Heck, Suzuki, and Stille reactions. Also a few examples of carbon-heteroatom bond formation in pyrazines are known. This perspective reviews recent progress in the field of transition metal-catalyzed cross-coupling reactions on pyrazine systems. It deals with the most important C-C- and C-X-bond formation methodologies.

Synthesis of a 7-azaindole by chichibabin cyclization: reversible base-mediated dimerization of 3-picolines

The lithium diisopropylamide (LDA)-mediated condensation of 2-fluoro-3-picoline and benzonitrile to form 2-phenyl-7-azaindole via a Chichibabin cyclization is described. Facile dimerization of the picoline via a 1,4-addition of the incipient benzyllithium to the picoline starting material and fast 1,2-addition of LDA to benzonitrile cause the reaction to be complex. Both adducts are shown to reenter the reaction coordinate to produce the desired 7-azaindole. The solution structures of the key intermediates and the underlying reaction mechanisms are studied by a combination of IR and NMR spectroscopies.

Discovery of 4-azaindoles as novel inhibitors of c-Met kinase

A series of 4-azaindole inhibitors of c-Met kinase is described. The postulated binding mode was confirmed by an X-ray crystal structure and series optimisation was performed on the basis of this structure. Future directions for series development are discussed.