Palladium-catalyzed Mizoroki-Heck reaction

It is worth noting that the diastereoselectivity of these direct arylations turned out to be complementary to palladium-catalyzed Mizoroki-Heck reactions (Scheme 25). 

Haneda, S., Ueba, C., Eda, K. and Hayashi, M. (2007) Imidazole and imidazoline derivatives as IV-donor ligands for palladium-catalyzed Mizoroki-Heck reaction. Adv. Synth. Catal., 349, 833-5. 

Mino, T., Shirae, Y, Sasai, Y. et al. (2006) Phosphine-free palladium catalyzed Mizoroki-Heck reaction using hydrazone as a ligand. J. Org. Chem., 71, 6834—9. 

Combination of the oxidative addition of aryl halide with olefin insertion followed by -hydrogen elimination provides a useful olefin arylation process catalyzed by a palladium complex (Mizoroki-Heck reaction) [63-65]. The essential part of the catalytic cycle is shown in Scheme 1.23. 

Doi, T., Fujimoto, N., Watanabe, J. and Takahashi, T. (2003) Palladium(0)-catalyzed Mizoroki-Heck reaction and Rh(I)-catalyzed asymmetric hydrogenation of polymer-supported dehydroalanine system. Tetrahedron Lett., 44, 2161-5. 

Reetz et al. reported phosphine-free, paUadium-catalyzed Mizoroki-Heck reactions of unactivated aryl halides using paUadium(O) nanoparticles [23, 24]. The thermolytic decomposition of Pd(OAc)2 at 130°C in the presence of ammonium salts resulted in the formation of R4N X -stabilized palladium(O) nanoparticles (Scheme 7.6). The decisive role of palladium colloids was secured by nuclear magnetic resonance (NMR) studies of the oxidative addition step yielding PhPdl and PhPdX3. ... 

An acridinylidene palladium carbene complex, starting from 9-chloro-10-methylacridine and Pd(PPli3)4 by oxidative addition at 60 °C in toluene in 53% yield, was applied to catalyze Mizoroki—Heck reactions of 190 and 191 to 192 (Scheme 75). Increasing the catalyst concentration to 0.001 mol% with respect to the palladium, an almost quantitative conversion was measured by gas chromatography (2006ASC1862). 

An example of a microflow continuous palladium-catalyzed Mizoroki-Heck coupling between iodobenzene with butyl acrylate, in combination with continuous microextraction/ catalyst recyclation was reported by Liu and coworkers (Liu et al., 2004). Their reaction was catalyzed by a [Pd(PPh3)Cl2(BMIM)] carbene complex, which was immobilized in the low-viscosity ionic liquid l-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][(CF3S02)2N]). Using automated microflow apparatus (Figure 7), iodobenzene, butyl acrylate, and tripropylamine were introduced from one inlet of the micromixer (channel width 0.1 mm, inner volume 2 mL), and the ionic liquid containing the Pd catalyst was introduced from the other inlet. Two solutions were mixed in the microreactor and were pnimped into the temperature controlled residence time unit. 

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-... 

Bulky ligands as above have also proved to be effective in other palladium-catalyzed reactions of aryl halides, e.g., amination [16-19], Suzuki-Miyaura reaction [20-22], Mizoroki-Heck reaction [23, 24], Migita-Kosugi-Stille reaction [25], and aryloxylation and alkoxylation [26-28] as well as the reaction with various carbon nucleophiles as described below. The ligands are considered to enhance both the initial oxidative addition of aryl halides and the reductive elimination of products [29, 30]. The effectiveness of the commercially available simple ligand, P(f-Bu)3, was first described for the amination by Nishiyama et al. [16]. 

Palladium-catalyzed arylation and vinylation of alkene is referred to as the Mizoroki-Heck reaction and is one of the most widely used Pd(0)-catalyzed C-C bond formations in organic synthesis. However, the reaction has not been extensively employed for C-glycosylation [96]. The example shown in O Scheme 67 outlines the reaction of iodopyridine and furanose gly-cal for the synthesis of C-nucleoside [97]. The mechanism began with the oxidative addition of iodopyridine to Pd(0) catalyst, and the resulting organo-palladium species was inserted by... 

Scheme 1.23. Mechanism of palladium-catalyzed arylation of olefins (Mizoroki-Heck reaction).

Palladium-catalyzed C-C bond formation 2.3.5.1 The Mizoroki-Heck reaction... 

The Mizoroki-Heck reaction, a palladium-catalyzed coupling of olefins with aryl or vinyl halides/triflates, is a powerful method for carbon-carbon bond formation. " " High efficiency is usually obtained only by starting from expensive aryl iodide (or bromide) or by using a fairly large amount of catalyst. Improvement of the catalytic activity as well as recovery and recycling of the catalyst is needed. 

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. 

Asymmetric intermolecular Mizoroki—Heck reaction From phosphine/ phosphinite-nitrogen to phosphite-nitrogen hgands 12IJC572. Asymmetric palladium-catalyzed intramolecular Wacker-type cycliza-tions of unsaturated alcohols and amino alcohols to give O- and N-het-erocycles 13MOL6173. 

Kamikawa, K., Harada, K. and Uemura, M. (2005) Catalytic asymmetric induction of planar chirality palladium catalyzed intramolecular Mizoroki-Heck reaction of prochiral (arene)chromium complexes. Tetrahedron Asymmetry, 16, 1419-23. 

Palladium-Catalyzed Arylation Reactions of Alkenes (Mizoroki-Heck Reaction and Related Processes)... 

In the Mizoroki-Heck reaction, the catalysis begins with the oxidative addihon of a C(sp )—X bond to a palladium(O) complex to give a C(sp )—Pd(II) complex common to almost all palladium(O)-catalyzed cross-coupling reachons (cf. Section 7.2.1). There are, however, alternative ways to generate the central o-aryl palladium(II) intermediate and to effect a Mizoroki-Heck-type process (Scheme 7.42). 

Scheme 7.53 Different modes of cyclization palladium(ll)-catalyzed oxidative Mizoroki-Heck reactions of indoles.

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