The Type 3 Catalytic System

23 Four Types of Intermolecular Mizoroki-Heck Catalytic System 23.1 The Type 1 Catalytic System 

It should be noted that extreme care should be exercised when designing catalytic systems for type 1 reactions and in interpreting the results. As soon as these reactions are effectively catalysed by trace amounts of almost any palladium precursor, the nature of catalytically active species cannot be reliably established. Hence, the effects and the real role of potential components of the catalytic system are in question. As a result, the suggestion of catalytic reactions in the absence of deliberately added precatalysts or in the presence of palladium compounds, which are well known not to release palladium, is illegitimate [72, 73]. 

From a preparative viewpoint, type 1 reactions are reliable, high yielding, allow for simple scale-up and are easily optimized. Application of these processes to other substrate-alkene pairs is usually successful as long as the aryl hahde is sufficiently activated towards oxidative addihon. 

On demand, such processes achieve very high TONs or TOP values after ophmization using various published SRPCs. We note here that any reported ultrahigh TONs and TOP values are difficult to reproduce. 

An interesting realizahon of a type 1 system is the so-called recyclable protocols, in which only a minor porhon of the initially added SRPC is consumed. The major portion remains intact and might be reused. 

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