Suzuki reactions poly

The Suzuki reaction was also used to prepare the polyketone since this particular reaction tolerates the subsequent step (Scheme 6.19).135 Palladium-catalyzed cross-coupling of aromatic diacid chlorides and bis(trimethylstannane) monomers was utilized to prepare poly(arylene ether ketone)s.136... 

As an example, consider the use of PVPy as a solid poison in the study of poly(noibomene)-supported Pd-NHC complexes in Suzuki reactions of aryl chlorides and phenylboroiuc acid in DMF (23). This polymeric piecatalyst is soluble under some of the reaction conditions employed and thus it presents a different situation from the work using porous, insoluble oxide catalysts (12-13). Like past studies, addition of PVPy resulted in a reduction in reaction yield. However, the reaction solution was observed to become noticeably more viscous, and the cause of the reduced yield - catalyst poisoning vs. transport limitations on reaction kinetics - was not immediately obvious. The authors thus added a non-functionalized poly(styrene), which should only affect the reaction via non-specific physical means (e.g., increase in solution viscosity, etc.), and also observed a decrease in reaction yield. They thus demonstrated a drawback in the use of the potentially swellable PVPy with soluble (23) or swellable (20) catalysts in certain solvents. 

Many poly(p-phenylenes) have since been synthesized by such Suzuki reactions [137]. 

Some of the most widely studied organic reactions at this time are palladium catalysed carbon-carbon cross coupling reactions, which have been extensively investigated in water. For example, palladium catalysed Suzuki reactions can be performed in water in the presence of poly (ethylene glycol) (PEG). It should be noted that the PEG may be playing the role of a surfactant (PTC) and/or a support for the metal catalyst in water. Interestingly, in this example, no phosphine is needed and the products are easily separated and the catalyst phase reused. Unfortunately, diethyl ether was used to extract the product and as this solvent is hazardous (low flash point and potential peroxide formation), the overall process would be greener if an alternative solvent could be used. 

Later, the same methodology was applied by Wallow and Novak for the synthesis of water-soluble poly(p-phenylene) derivatives via the poly-Suzuki reaction of 4,4 -biphenylylene bis(boronic acid) with 4,4 -dibromodiphenic acid in aqueous di-methylformamide [26]. These aromatic, rigid-chain polymers exhibit outstanding thermal stability (decomposition above 500 °C) and play an important role in high-performance engineering materials [27] conducting polymers [28] and nonlinear optical materials [29]. 

Reaction of aryl halides with boronic acids catalyzed by palladium compounds (Suzuki reaction) is one of the most versatile reactions for selective formation of carbon-carbon bonds. One of the first reports of the application of microwaves to this type of reaction was published by Larhed et al. in 1996 [115]. Subsequently, Varma et al. described the Suzuld-type coupling of boronic acids and aryl halides (Eq. 80) in the presence of palladium chloride and poly(ethylene glycol) (PEG-400) under the action of MW irradiation [116]. The reactions were performed at 100 °C to give the desired coupling products in 50 to 90% yield within 50 s. The coupling reaction can be also conducted under conventional conditions (oil bath, 100 °C), but to achieve similar yields a longer reaction time was needed (15 min). It was found that addition of KE affords better yields. 

Among the first examples of so-called liquid-phase synthesis were aqueous Suzuki reactions employing poly(ethylene glycol) (PEG)-bound aryl halides and sulfonates in palladium-catalyzed cross couplings [71]. It was shown that no additional phase-transfer catalyst (PTC) was needed when the PEG-bound electrophiles were coupled with aryl boronic acids in water under microwave irradiation conditions, in sealed vessels, in a domestic microwave oven (Scheme 16.49). Work-up involved precipitation of the polymer-bound biaryl from a suitable organic solvent with ether. 

Pittelkow, M., Moth-Poulsen, K.,et al. Poly(amidoamine)-Dendrimer-Stabilized Pd(0) Nanoparticles as a Catalyst for the Suzuki Reaction. Langmuir,l 9(18), 7682-7684 (2003). 

Thiophene Copolymers. A copolymer from N-vinylcarbazole and thiophene, poly(2,7-bi-2-thienyl-9-vinyl-9-//-carbazole) was synthesized via a radical polymerization and a Suzuki reaction [58]. 

Of all the chemical processes which were reviewed and described in references [1-3], it should be noted that up to now only the Kovacic and Yamamoto reactions and, to a lesser extent, the thermal dehydrogenation of poly(l,3-cyclohexadiene) have been used to synthesize polyphenylenes for usual or special applications. Only recently, a new impulse has been given to the synthesis of linear functionalized high molecular-weight PPPs with the adaptation of the Suzuki reaction, and this is currently one of the best possible ways of synthesizing soluble, functionalized PPPs for specific applications with, in particular, the realization of rigid rod-like polymers for mechanical applications, as will be shown in Section 2.1.3. 

A soluble derivative of (64) was prepared by the Suzuki reaction [121]. The polymer (67) was soluble in chloroform and was 52, corresponding to 104 aromatic rings. The Amax and bandgap were 333 and 392 nm, respectively. A few benzene derivatives were also copolymerized with (65), but the Dp of the resulting copolymers was much lower than poly(67), due to die low reactivity of dibromobenzenes. 

With the first method, Schluter [180,181] utilized the Suzuki reaction to produce a poly(p-phenylene)-type backbone possessing reactive ort/to-hydroxy-methyl substituents. These substituents were subsequently used to couple a variety of Frechet-type monodendrons along the backbone as described in Figure 26. In general, the lower generations (i.e., G = 1) coupled with... 

As for poly(p-phenylene), there are two important methods the Ni-catalyzed coupling of Yamamoto and Colon, on the one hand, and the Suzuki reaction based on the coupling of aromatic boronic acids with halogenated aromatic compounds in the presence of a Pd(0) catalyst, on the other. Besides these two main methods, a series of other metal-catalyzed couplings have been explored. 

For carbon nanotubes, organosoluble PS-SWCNT nanocomposites [292] have been prepared that could be efficiently transformed to highly hydrosoluble, pH-responsive materials via direct sulfonation of the grafted PS chains [296]. In another approach, MWCNT-C H was clicked with azide-functionalized poly(glycerol methacrylate) and the final hairy MWCNTs were used for the in situ synthesis and immobilization of monodisperse 3 nm-sized palladium nanoparticles. The final heterostructure had a high catalytic activity (77%) for the C-C coupling Suzuki reaction between 4-bromobenzene and phenyl boronic acid [293],... 

In recent years, extensive investigations have been performed on the use of nickel rather than palladium complexes for catalyzing the Suzuki reaction,and indeed, several recent studies have also concerned the catalytic properties of poly-NHC complexes of nickel(II), particularly with pincer-type hgands best results were obtained with CNC complex 67, which exhibited good catalytic activity at 100 °C even with aryl chlorides as well as with aryl tosylates and mesylates. Triphenylphosphane was however required as a cocatalyst. 

Finally, an asymmetric variant of the Suzuki reaction was developed using as catalyst a poly-NHC metal complex with hgand 2 (see also Section 2.1). The complex exhibited a rather low catalytic activity toward aryl iodides and bromides as substrates. However, chiral binaphthyls were prepared with ees up to 70%. ... 

Over the past two decades, Suzuki polycondensation has become one of the most efficient methods for the synthesis of conjugated polymers. As another important cross-coupling protocol, the Suzuki-Miyaura cross-coupling reaction was invented by Suzuki and co-workers in 1979 The scope of the Suzuki reaction for synthetic applications has been surveyed in several excellent reviews by Kotha, Lahiri, Kashinath, Miyaura and Fu. The Suzuki-Miyaura cross-coupling reaction provided deeper insights into how to connect two specific sp -hybridized C-atoms more efficiently and under milder conditions. The Suzuki-Miyaura cross-coupling reaction was first used by Schlueter et al. to prepare poly(para-phenylene)s. ... 

The side reaction responsible for the coupling of phenyl groups from triphenylphosphine with the organic electrophile (see 148) has also been identified as being capable of incorporating phosphorous into poly(p-phenylene)s synthesized by the Suzuki reaction (249). 

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