Polymerization Suzuki-coupling synthesis

At about die same time, die application of the Suzuki coupling, the crosscoupling of boronic acids widi aryl-alkenyl halides in die presence of a base and a catalytic amount of palladium catalyst (Scheme 9.12),16 for step-growth polymerization also appeared. Schliiter et al. reported die synthesis of soluble poly(para-phenylene)s by using the Suzuki coupling condition in 1989 (Scheme 9.13).17 Because aryl-alkenyl boronic acids are readily available and moisture stable, the Suzuki coupling became one of die most commonly used mediods for die synthesis of a variety of polymers.18... 

Ruthenium-catalysed Ring-Opening Metathesis Polymerization (ROMP) 29 526 529 (Equation 10) and Pd(tppms)3-catalysed synthesis of water soluble poly-(p-phenylene) derivatives (Equation ll).530 The latter is a special example of a Suzuki coupling (see earlier). 

Suzuki coupling chemistry of benzene boronic acid derivatives and haloben-zenes using a Pd(0) catalyst has also been employed for the synthesis of substituted PPPs as illustrated by the A-B type monomer 16 [67-73]. These initial syntheses were carried out under heterogeneous conditions at a basic pH as illustrated by Scheme 21. Such Suzuki coupling polymerizations are rather attractive alternatives as a wide variety of functional groups can be tolerated with minimal interference in the coupling scheme. 

As was shown earlier with the Suzuki coupling reactions, organopalladium intermediates can show good stability to water and other protic sources. This stability has been exploited in the synthesis of polyacetylene under air- and moisture-stable conditions. It was found that simple palladium(II) salts (PdCl2, Pd(CH3C02)2, etc.) can be used to initiate the 1,2-insertion polymerization of strained cyclic alkenes in water (eq. (8)) [31]. Once formed, poly-8 can be converted to polyacetylene through a retro-Diels-Alder reaction. 

Transition metal catalyzed coupling reactions of aromatic halides, such as Heck or Suzuki coupling, are used extensively for the synthesis of low-molecular-weight organic compounds. With bifunchonal substrates, polymers can be obtained. By contrast to all other polymerization reactions considered in this chapter, such reactions represent step-growth-type polymerizations. 

The use of Suzuki coupling for the synthesis of polyphenylene polymers was introduced by Rehahn, Schluter, and Wegner (Eq. 8) [87]. Poly(p-2,5-di-n-hexylpheny-lene) was prepared in a biphasic mixture of benzene and water as a reaction medium, using sodium carbonate as a water-soluble base. This AB-type polymerization afforded polymers containing an average of about 28 phenylene units. 

Using the example of the Suzuki-coupling reaction as a common synthesis route for polymeric semiconductors, the economic and ecologic improvements... 

We will start this chapter with a brief review of the origin of the donor-acceptor concept, followed by a short summary of the key chemistries that are used for the synthesis of D-A copolymers e.g., Suzuki coupling and Stille coupling), with a focus on their application towards the polymer synthesis. The classical step-growth polymerization will be next discussed within the context of Pd-catalyzed polycondensation. Then we will briefly discuss two recent, interesting advances in the synthesis of D-A copolymers Pd-free polycondensation and chain-growth Suzuki polymerization. Since the synthesis of D-A... 

Use of the Suzuki coupling reaction in the synthesis of PPPs has been reported. For example. Wallow and Novak [31] have polymerized 19 and 20 in the presence of palladium(O) catalyst to generate 21, a water-soluble PPP (Scheme 9). We have... 

Guillerez and Bidan [604] recently described a new synthesis of highly regioregular poly(3-octyl-thiophene) based on the Suzuki coupling reaction. The stable polymerizable precursor which bore an iodo and boronic ester derivative in the 2 and 5 positions was obtained in two steps from the 3-octyJ monomer. Polymerization of this in the presence of Pd(II) acetate gave a final CP said to contain up to 97% of head-to-tail couplings. This synthesis is summarized in Fig. 14-4. 

Typical polyphenylenes can be obtained by means of the polymerization types. Early research on sulfonated afkoxyl PPs utilized dibromo- and diboronic acid-substituted precursors via Suzuki coupling reaction for the polymer synthesis, as shown in Figure 6.1 [4]. 

Anderson et al. [34] reported the synthesis of conjugated polyrotaxanes encapsulated by cyclodextrin rings, as shown in Fig. 6. The hydrophobic diboronic acid monomer was encapsulated inside the cyclodextrin rings and polymerized by Suzuki coupling with a water-soluble diiodide monomer and terminated with bulky naphthalene stoppers to form the corresponding insulated molecular wires. 

The palladium-catalyzed coupling of boronic acids with aryl and alkenyl halides, the Suzuki reaction, is one of the most efficient C-C cross-coupling processes used in reactions on polymeric supports. These coupling reactions requires only gentle heating to 60-80 °C and the boronic acids used are nontoxic and stable towards air and water. The mild reaction conditions have made this reaction a powerful and widely used tool in the organic synthesis. When the Suzuki reaction is transferred to a solid support, the boronic add can be immobilized or used as a liquid reactant Carboni and Carreaux recently reported the preparation of the macroporous support that can be employed to efficiently immobilize and transform functionalized arylboronic adds (Scheme 3.12) [107, 246, 247]. 

A different approach to the synthesis of oligo[2]calenanes was chosen by Mullen et al. in 1995 [57]. The bromo-substituted in/out catenane 111 was coupled with appropriate comonomers under Suzuki conditions [58]. The degree of polymerization was between one and five for the resulting oligomers 112 (Figure 45). In 1997 the same group reported the first synthesis of poly[2]catenanes of the... 

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