Mizoroki-Heck cross-coupling reaction

One-Pot Sequential Mizoroki-Heck/Cross-Coupling Reaction. ( )-4-[2-(4-Acetyl-phenyl)-l-butylethenyl]benzoic Acid Ethyl Ester (171)... 

Aromatic carboxylic anhydrides have been found to be suitable substrates as aryl sources in the Pd-mediated decarboxylative Mizoroki-Heck cross-coupling reaction (Scheme 22.26) [38]. Olefins with electron-withdrawing groups generally give high yields of the (ii)-P-arylated products. With terminal olefins, a very rapid isomerization occurs and the arylated products are obtained as a mixture of isomers. 

Gao, X., Takeda, K., Zhu, Y., Nakanishi, K., and Shimada, T. (2014) A new hierarchically porous Pd HSQ monolithic catalyst for Mizoroki-Heck cross-coupling reaction. JVew /. Chem., 38, 1144-1149. 

Carbon-carbon bond formation reactions and the CH activation of methane are another example where NHC complexes have been used successfully in catalytic applications. Palladium-catalysed reactions include Heck-type reactions, especially the Mizoroki-Heck reaction itself [171-175], and various cross-coupling reactions [176-182]. They have also been found useful for related reactions like the Sonogashira coupling [183-185] or the Buchwald-Hartwig amination [186-189]. The reactions are similar concerning the first step of the catalytic cycle, the oxidative addition of aryl halides to palladium(O) species. This is facilitated by electron-donating substituents and therefore the development of highly active catalysts has focussed on NHC complexes. 

Transition metal-catalysed reactions have emerged as powerful tools for carbon-carbon (C-C) bond formation [1], Cross-coupling reactions (Suzuki-Miyaura, Mizoroki-Heck, Stille, etc.) are recognised to be extremely reliable, robust and versatile. However, some other catalysed arylation reactions have been studied and have been reported to be very efficient [2]. In recent years, A -heterocyclic carbenes (NHC) have been extensively studied and their use as ligands for transition-metal catalysis has allowed for the significant improvement of many reactions [3]. This chapter highlights the use of NHC-bearing complexes in those arylation reactions. 

Other successful examples of catalysts containing NHC ligands are found in palladium- and nickel-catalyzed carbon-carbon bond formations. The catalyst development with these metals has focused in particular on Heck-type reactions, especially the Mizoroki-Heck reaction itself [Eq. (42)] and various cross coupling reactions [Eq. (43)], e.g., the Suzuki-Miyaura reaction ([M] = and the Kumada-Corriu reaction ([M] = MgBr). " Related reactions like the Sonogashira coupling [Eq. (44)]326-329 Buchwald-... 

The catalytic activity of benzothiazole-oxime-based Pd (Il)-complexes (xxxv) was evaluated in Suzuki-Miyaura and Heck-Mizoroki C-C cross coupling reactions of aryl bromides and chlorides with aryl boronic acid and olefins under microwave conditions in water was studied by Dawood [55]. 

For example de Meijere A, Diederich F (eds) (2004) Metal-catalyzed cross-coupling reactions, second completely revised and enlarged editirai, vol 2. Wiley-VCH, Weinheim, 437 pp Oestreich M (2009) The Mizoroki-Heck reactioiL Wiley, Hoboktai, NJ, 938 pp Farina V, Scott WJ (1998) The Stille reactirm. Wiley, New York, NY, 672 pp Li JJ, (jribble GW (2006) Palladium in heterocyclic chtanistry, 2nd edn. Pergamon/Elsevier, Oxford... 

The Suzuki-Miyaura cross-coupling reaction is a standard method for carbon-carbon bond formation between an aryl halide or triflate and a boronic acid derivative, catalyzed by a palladium-metal complex. As with the Mizoroki-Heck reaction, this cross-coupling reaction has been developed in ionic liquids in order to recycle and reuse the catalyst. In 2000, the first cross-coupling of a halide derivative with phenylboronic acid in [bmim] [BF4] was described. As expected, the reaction proceeded much faster with bromobenzene and iodobenzene, whereas almost no biphenyl 91 was obtained using the chloride derivative (Scheme 36). The ionic liquid allowed the reactivity to be increased, with a turnover number between 72 and 78. Furthermore, the catalyst could be reused repeatedly without loss of activity, even when the reaction was performed under air. Cross-coupling with chlorobenzene was later achieved - although with only a moderate yield (42%) - using ultrasound activation. 

Batsanov, A.S., Knowles, J.P. and Whiting, A. (2007) Mechanistic studies on the Heck-Mizoroki cross-coupling reaction of a hindered vinylboronate ester as a key approach to developing a highly stereoselective synthesis of a C1-C7 Z,Z, -triene synthon for virideno-... 

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]. 

Although the combination of a Mizoroki-Heck and a cross coupling reaction has not been yet exploited very much, its application and development have recently been increased. In some examples, the advantage of the comparable high reaction rate of the d5-palladation of alkynes over alkenes is used to carry out a Suzuki, Stille or Souogashira reaction after the oxidative addition and the d -palladation of an alkyne. Moreover, the first step is quite often an intramolecular transformation taking advantage of (he entropic effect, but this is not a requirement. 

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. 

Transition-metal-mediated transformations play an important role in combinatorial synthesis on solid supports because they allow C-C bond formation under mild, neutral conditions and tolerate a broad range of functional groups. In particular, the palladium-mediated cross-coupling reactions, more precisely the Mizoroki-Heck, the Suzuki and the Stille reactions received a lot of attention due to their enormous derivatization potential of functional structures [5]. Although Stille coupling was the first to be explored on and... 

Having seen steps such as oxidative addition, insertion, and reductive elimination in the context of transition metal-catalyzed hydrogenation using Wilkinsons catalyst, we can now see how these same types of mechanistic steps are involved in a mechanism proposed for the Heck-Mizoroki reaction. Aspects of the Heck-Mizoroki mechanism are similar to steps proposed for other cross-coupling reactions as well, although there are variations and certain steps that are specific to each, and not all of the steps below are involved or serve the same purpose in other cross-coupling reactions. 

The beauty of this chemistry was then elaborated by Itami and Yoshida et al., who developed 2-pyridyl- and 2-pyrimidyl-directed Mizoroki-Heck multiarylahons [53]. The pivotal feature of their platforms 96 and 97 (Figure 7.2) is the tethering bond itself, which serves as a placeholder for an aryl group by unique cross-coupling reactions of the C(sp )—Si and C(sp )—S bond, respectively. 

Scheme 3.39 Some of the most important cross-coupling reactions catalyzed by Pd (i)Suzuki-Miyaura, (ii) Heck-Mizoroki, (iii) Sonogashira, (iv) Hiyama, and (v) Stille.

Thus, low loadings of palladium without added ligand can be used in cross-coupling reactions such as the Mizoroki-Heck reaction of atyl bromides, but only when the palladium-substrate ratio is kept particularly low, typically from 0.01-0.1 mol%. Quenching of ionic species (into metal colloids) is less likely at lower concentrations due to a lower collision frequency. Pd black formation is a catalytic dead end. At too low a concentration, the reaction will proceed slowly, if at all. - ... 

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