Diphenylphosphorylated PEG (DPPPEG) as a new support for generation of nano-Pd(0) as catalyst for carbon–carbon bond formation via copper-free Sonogashira and homocoupling reactions of aryl halides in PEG

Oxidative and Reductive Cross-Coupling Reactions Catalyzed by an Anionic “Ligandless” Palladium Complex

“…Among the most straightforward and well-established methods are palladium-catalyzed cross-coupling reactions. − While the Mizoroki–Heck reaction allows access to stilbenes (Scheme a), − the Suzuki–Miyaura reaction, among others, yields biphenyls (Scheme b). − However, most of these cross-coupling reactions suffer from low atom economy and the necessity to use toxic, air-sensitive organometallic reagents. − Among the required aryl halides, aryl chlorides are the reaction partners of choice since they are less expensive, but on the other side, they are also less reactive. One approach to attenuate these drawbacks is the development of the oxidative Heck reaction − of a boronic acid (as a surrogate for the aryl halide) and an alkene for the synthesis of stilbenes (Scheme a). − A viable alternative for the synthesis of symmetric biphenyls is the reductive homodimerization of aryl halides (Scheme b). − …”