Multicomponent Mizoroki-Heck Reactions

Multicomponent reactions are particularly viable procedures for combinatorial synthesis. The clear advantage of conducting these reactions on solid supports lies in the fact that all nonpolymer-bound components (e.g. excess of reagents) can simply be removed. 

This cleavage of the triazene linker with subsequent Mizoroki-Heck reaction is interesting in the sense that it adds yet another dimension of diversity by offering an additional possibility of functionalization. 

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In general, intermolecular Mizoroki-Heck reactions using immobilized alkenes are not as common as the variant that deals with solid-supported aryl halides, but we will come across another example in Section 14.2,3 on multicomponent Mizoroki-Heck reactions. 

In Mizoroki-Heck reactions, the developer cannot just rely on ligands. All components of the catalytic system strongly influence the nature of the catalytic species. The nature of the ligands in the coordination sphere of the catalytically active species often remains unknown, being speculative at the most. More often than not, Mizoroki-Heck reactions proceed through intermediates with coordination shells filled by undefined ancillaries. The art of the Mizoroki-Heck reaction designer is thus the systematization and judicious choice of a multicomponent catalytic system involving substrates, reaction media, bases and additives. It should not be overlooked that the nature of the palladium complexes involved heavily depends on temperature. 

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