Pd(0) and Ni(0) catalyzed polymerization reactions

Abstract

Three novel metal catalyzed cross‐coupling polymerization reactions which result in carbon‐carbon bond formation are described and discussed in context with other metal catalyzed cross‐coupling polymerization reactions. Diarylacetylene monomers and dimers are prepared by the phase transfer Pd(0)/Cu(I) catalyzed coupling of aryl halides with 2‐methyl‐3‐butyn‐2‐ol. Aryl‐alkyl bond forming polymerization reactions are achieved by the phase transfer Pd(0) catalyzed coupling of B‐alkyl‐9‐borabicyclo[3.3.1]nonane derivatives with aryl halides. Soluble polyphenylenes are prepared by the Ni(0) catalyzed homocoupling of substituted phenylenebistriflates in the presence of zinc.

Regioregular and Regioirregular Poly(p-phenylene)s via Ni(0)-Catalyzed Homocoupling of Arylene Bismesylates

“…Aryl bismesylates were synthesized by the reaction of methanesulfonyl chloride with the corresponding phenol in pyridine 2a 4‘-fluoro-2,5-bis[(methylsulfonyl)oxy]benzophenone ( 6e ),2a 2-methyl-1,4-bis[(methylsulfonyl)oxy]benzene ( 6f ),2a 2,2‘-dibenzoyl-4,4‘-bis[(methylsulfonyl)oxy]biphenyl ( 9a ),5c 2,2‘-bis( p -fluorobenzoyl)-4,4‘-bis[(methylsulfonyl)oxy]biphenyl ( 9e ),5c and 2,2‘-bis( p - tert -butylbenzoyl)-4,4‘-bis[( methylsulfonyl)oxy]biphenyl ( 9b ) 5c were synthesized as reported previously.…”

“…Synthetic procedures for the preparation of substituted and unsubstituted poly( p -phenylene)s (PPP) can be classified as direct or indirect methods. − The two most efficient direct methods for the synthesis of PPP are based on the Suzuki cross-coupling and Ni(0)-catalyzed homocoupling reactions. − The application of Ni(0)-catalyzed homocoupling reactions to the synthesis of PPP was elaborated in our laboratory. ,3a Both substituted 1,4-dihalobenzenes (i.e., dibromo and dichloro) 2a,b,d,e and bis(sulfonates) of substituted hydroquinones and other dihydroxyarylenes 2a-c,3a were used as monomers in Ni(0)-catalyzed polymerization reactions. In our first series of experiments, chlorine and bromine groups were used only as models for the sulfonate leaving groups.…”

“…Since a large number of substituted hydroquinones and bisphenols are available commercially and readily through published procedures, this broadens considerably the scope of this synthetic methodology. However, the extensive application of this methodology to the synthesis of PPP has been slow since the very expensive triflate was the first successful leaving group used. 2a-c…”

“…The melting temperature and the rate of crystallization of PPP can be decreased by increasing its configurational and conformational entropy , (b) increasing the number of constitutional isomers of the aromatic repeat units, 2b, (c) generating a linear chain conformation from various meta and other phenylenic units,2e and (d) decreasing the rate of interconversion between the pseudo-atropisomeric conformers (i.e., replacing a 4,4‘-diphenylene with a 4,4‘-binaphthylene). 2c,f, The most soluble PPP obtained to date contained long alkyl pendant groups. 8a,c-e Their solubility is due to the high entropy generated by the large number of conformational isomers of the side groups. When small substituents, which have few conformational or configurational isomers, are used, an enhancement of the overall entropy can be obtained only by increasing the number of constitutional isomeric monomeric repeat units.…”

Microwave‐Assisted Polymer Synthesis: Recent Developments in a Rapidly Expanding Field of Research

“…CC coupling procedures are often applied for step‐growth polymerization resulting in conjugated polymers that can be applied in, e.g., light‐emitting diodes, solar cells, and organic field effect transistors 34–36. These CC coupling procedures are often based on metal catalysis which might benefit from microwave irradiation by specific absorption of the metal ions.…”