Negishi coupling standard

Solvents play a pivotal role in the Negishi coupling, as demonstrated in the coupling of alkenyl zinc reagents with iodo alkenes. In this case, DMF is superior to THF, one of the standard solvents (Scheme 5-77). 

In conclusion, the fantastically diverse chemistry of indole has been significantly enriched by palladium-catalyzed reactions. The accessibility of all of the possible halogenated indoles and several indolyl triflates has resulted in a wealth of synthetic applications as witnessed by the length of this chapter. In addition to the standard Pd-catalyzed reactions such as Negishi, Suzuki, Heck, Stille and Sonogashira, which have had great success in indole chemistry, oxidative coupling and cyclization are powerful routes to a variety of carbazoles, carbolines, indolocarbazoles, and other fused indoles. 

Bipyridines are readily prepared by cross-coupling reactions and the Negishi reaction is no exception [35]. Organozinc 99, prepared in standard fashion from 19, could be cross-coupled with 102 to generate 100. Triflate 102 was prepared from aminopyridine 101 via diazotization followed by formation of the triflate. 

The pyridyl group has also been immobilized on the resin and was able to survive lithiation conditions necessary to prepare the halopyridine [62]. This approach has also been applied to the Sonogashira, Stille, and Negishi reactions vide infra). In the Suzuki example, the resin-bound pyridine 177 can be converted to the haloderivative 178 using standard lithiation chemistry. With 178 in-hand, cross-coupling and cleavage from the resin afforded 179. 

The formation of C-C bonds is one of the important fields of synthetic organic chenustry. Modern methods are in the focus of scientists in academia and industry, often being connected to catalysis. Products based on catalysis represent more than 90% of the total amount of new compounds. Presently, palladium-catalysed reactions play a dominant role. For example, Mizoroki-Heck reactions, as well as Stille, Suzuki, Negishi, Kumada and Sonogashira couplings, are in the standard toolbox of organic chemists [1]. 

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