Domino reactions Mizoroki-Heck/Stille

Scheme 8.26 Combination of a domino Mizoroki-Heck/Stille reaction with C—H activation.

In most of the palladium-catalysed domino processes known so far, the Mizoroki-Heck reaction - the palladium(0)-catalysed reaction of aryl halides or triflates as well as of alkenyl halides or triflates with alkenes or alkynes - has been apphed as the starting transformation accordingly to our classification (Table 8.1). It has been combined with another Mizoroki-Heck reaction [6] or a cross-coupling reaction [7], such as Suzuki, Stille or Sonogashira reactions. In other examples, a Tsuji-Trost reaction [8], a carbonylation, a pericyclic or an aldol reaction has been employed as the second step. On the other hand, cross-couphng reactions have also been used as the first step followed by, for example, a Mizoroki-Heck reaction or Tsuji-Trost reactions, palladation of alkynes or allenes [9], carbonylations [10], aminations [11] or palladium(II)-catalysedWacker-type reactions [12] were employed as the first step. A novel illustrative example of the latter procedure is the efficient enantioselective synthesis of vitamin E [13]. 

In domino transition-metal-catalysed processes, cross-coupling reactions can also be nsed as the starting transformation. Most often, Suzuki, Stille and Sonogashira reactions are employed in this context. They can be combined with a Mizoroki-Heck reaction and other palladium-catalysed transformations. 

The Heck-Mizoroki reaction has also been heavily applied in one-pot sequential reaction sequences. The topic of sequential, domino, consecutive, or tandem catalytic reactions is a very timely subject, as at its core is efficiency, economy, and waste minimization in organic synthesis. In 2010 [59], one of us published a review of this topic which explains the current state of play and includes relevant references on the subject. However, the topic is still rather murky in terms of definitions, and this is something that we feel needs urgent attention. The Heck-Mizoroki is a very suitable transformation for inclusion in a sequential catalytic process, given that it leads to the formation of C=C units, a common functionality for further catalytic transformation. 

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