Asymmetric Suzuki-Miyaura coupling

Figure 9 Structures of well-defined Pd-NHC complexes used in asymmetric Suzuki-Miyaura coupling...

Table 2 Preparation of chiral binaphthyls in asymmetric Suzuki-Miyaura coupling catalyzed by 79...

It has been proven that the chiral Pd(II) complexes as transition metal catalysts vs Lewis acid catalysts bring a breakthrough in the frontier of catalytic asymmetric organic synthesis. Here we discussed the key issues based on asymmetric carbon-carbon bond formations anomalous six-membered ring formation, ene-type cyclization leading to five-membered rings, spiro cycliza-tion, alkaloid and quinoline synthesis, Suzuki-Miyaura coupling, and C-H bond activation/C-C bond formation by transition metallic Pd(II) catalysts. On the other hand, the carbonyl-ene reaction, hetero Diels-Alder reaction, and... 

Fujihara used BINAP derived ligands as stabilizers for Pd NPs, giving well dispersed nanoparticles with narrow size distribution. Using chiral phosphine ligands, including S-BINAP in the asymmetric Suzuki-Miyaura coupling of naphtyl bromides and aiylboronic acids at room temperature, moderate ees of up to 74% could be achieved (Scheme 2). ... 

Scheme 2 Use of chiral ligands as stabilizers of Pd NPs in an asymmetric Suzuki-Miyaura coupling.

Figure 13.3 Natural products for which an asymmetric Suzuki-Miyaura coupling reaction has been employed in their syntheses.

Scheme 13.26 Tang and co-workers asymmetric Suzuki-Miyaura coupling approach towards atropoisomeric compounds.

A dichromium derivative has been prepared from pinacol (dichloromethyl)-boronate (163), anhydrous chromous chloride, and lithium iodide in THF at 25 °C [90]. With various aldehydes, RCHO, this reagent adds to the carbonyl carbon to form trans-l-alkenylboronic esters, RCH=CH-B(02C2Me4). For most examples yields were 84-91%, E Z ratios >95 5. This reaction was used recently to convert aldehyde 162 into alkenylboronic ester 164, an intermediate used for a Suzuki-Miyaura coupling in the asymmetric total synthesis of quinine and quinidine (Scheme 8.39) [91]. In the modified procedure, the chromium reagent was generated from 163 in the presence of the aldehyde substrate. 

The most active NHCP system developed for Suzuki-Miyaura coupling so far was introduced by Shi et al. They investigated the chiral ferrocenyl NHCP system R-8, which was developed by Chung and coworkers for asymmetric hydrogenation (see Section 10.3), because of its resemblance to the famous Josiphos ligand, which, next to its performance in asymmetric catalysis, is also known for... 

A few other chiral NHCP systems have been reported, and their application in various palladium-catalyzed transformations such as hydroamination of a,P-unsaturated nitriles [32], asymmetric Suzuki-Miyaura coupling (see Section 10.2.1) [13n], and most frequently allylic substitution reactions have been studied [29, 33, 34]. Figure 10.3 summarizes the chiral NHCP systems not used in asymmetric hydrogenations, which we will present in the following. 

In this study, the full catalytic cycle for the recently reported asymmetric Suzuki-Miyaura coupling between 1 -bromo-2-methylnaphthalene (2) and 1 -naphthal eneboronic acid (3) catalyzed by a [Pd(bis-hydrazone)] (1) complex [47], was theoretically investigated by means of DFT calculations. Importantly, the results derived from this study revealed that the transmetalation reaction does not occur in just one step, but occurs in three steps. This is owing to the relative lability of the bis-hydrazone ligand, which can easily dissociate one of the N atoms coordinated to the Pd catalyst. Very recently, this variant for the transmetalation mechanism has been reported for the Suzuki-Miyaura coupling catalyzed by a diimine chelated palladium complex [15]. 

Last but not least, theoretical calculations on the investigated asymmetric Suzuki-Miyaura coupling showed that the mechanism for the transmetalation step differs from the typical reaction pathway proposed in the literature. This is owing to the relative lability of the bis-hydrazone ligand, which can easy dissociate one of the N atoms directly coordinated to Pd. As far as the stereochemistry of the reaction is concerned, calculations so far do not provide an explanation for the high enantios-electivities observed in the experiments. Two possible reasons are either the true pathway for the reaction has not been identified yet, or an interconversion among... 

Uozumi Y, Matsuura Y, Arakawa T, Yamada YMA. Asymmetric Suzuki-Miyaura coupling in water with a chiral palladium catalyst supported on an amphiphilic resin. Angew. Chem. Int. Ed 2009 48 2708 2710. 

On the other hand, Waldmann, Arndt, and co-workers succeeded in the assembly of biphenomycin B 11 via an early stage Suzuki-Miyaura coupling and a macrolactam-ization (Scheme 4.5). ° Their synthesis was also initiated by the PTC-catalyzed asymmetric alkylation. Treatment of... 

Mikami K, Miyamoto T, Hatano M. A highly efficient asymmetric Suzuki-Miyaura coupling reaction catalyzed by cationic chiral palladium(II) complexes. Chem. Commun. 2004 2082-2083. 

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