Poly Heck-coupling polymerization

The coupling reaction of aryl-alkenyl halides with alkenes in the presence of a palladium catalyst and a base is known as the Heck coupling (Scheme 9.4).6 Since the early 1980s, this type of coupling reaction has been used for die syndiesis of poly(arylenevinylene) and related polymers by polymerization of AB- or AA/BB-type of monomers (Scheme 9.5).7... 

The wide variety of coupling methods adapted from organic synthesis to condensation polymerization of just one CP can be appreciated from Fig. 5-12. for poly(pheny-lene). Typical condensations and eliminations adapted to syntheses of such CPs as poly(phenylene) and poly(phenylene vinylene) (P(PV)) are illustrated in Fig. 5-13. Fig. 5-14 shows the variety of precursor routes available to P(PV). More recently, the Yu group [86] has demonstrated application of Pd-catalyzed Stille and Heck reactions to the synthesis of poly(thiophene) (P(T)) derivatives (cf. Fig. 5-15. Besides the Grignard couplings such as shown in Eq. 1.6, Chapter 1, P(T) s can also be prepared via a variety of other procedures, such as Friedel-Crafts alkylation [87], and direct oxidation with FeClj as for P(Py) above. 

Scheme 4 shows the synthesis of poly(/7-arylenevinylene)-type (PAV-type) jT-stacked polymer by Heck-Mizoroki cross-coupling [24, 25]. The treatment of pseudo-/7ara-divinyl[2.2]paracyclophane 14 with diiodofluorene 15 using a Pd(OAc)2/P(o-Tol)3/NBu3 catalytic system afforded the corresponding stacked polymer 16 in 96 % isolated yield with M =5,200 [26]. Poly(/7-arylene)-type (PA-type) jc-stacked polymers were prepared by Suzuki-Miyaura cross-coupling [27, 28], and a representative example is shown in Scheme 5. The Pd(PPh3)4-catalyzed polymerization of monomer 9 with bis(boronic acid ester) monomer 17 afforded the polymer 18 in 89 % isolated yield (Mn=2,600) [29].

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