Highly Efficient Catalysts for Direct Arylation Polymerization (DArP)

• Published in: Asian journal of organic chemistry 2018-07, Vol.7 (7), p.1206-1216
• Main Authors: Wakioka, Masayuki, Ozawa, Fumiyuki
• Format: Article
• Language: English
• Subjects: Catalysis; Catalysts; Chemical reactions; Chemical synthesis; Coupling; defect prevention; direct arylation; Functional groups; Hydrogen bonds; ligand control; Organic chemistry; Palladium; palladium catalysts; polycondensation; Polymerization; Polymers; Solvents; Toluene; π-conjugated polymers
• ISSN: 2193-5807; 2193-5815
• DOI: 10.1002/ajoc.201800227

Recently, the palladium‐catalyzed direct arylation polymerization (DArP) has emerged as a viable alternative to conventional synthetic means of making π‐conjugated polymers based on catalytic cross‐coupling reactions. The DArP, which proceeds through C−H bond activation, has a distinct advantage over cross‐coupling polymerization in terms of fewer reaction steps and higher functional group tolerance. We have developed novel catalysts for DArP by using P(2‐MeOC6H4)3 (L1) and P(2‐Me2NC6H4)3 (L2) as ligands. Although common direct arylation catalysts require the use of strongly coordinating solvents such as DMA and DMF, our catalysts exhibit high activity in THF and toluene, which are good solvents for π‐conjugated polymers. Thus, we could realize the precise synthesis of highly head‐to‐tail regioregular poly(3‐hexylthiophene) (HT‐P3HT) and donor–acceptor type alternating copolymers (DA polymers) with well‐controlled structures through DArP. Simple, yet highly efficient! Palladium‐based catalysts have been developed for direct arylation polymerization (DArP) by using P(2‐MeOC6H4)3 (L1) and P(2‐Me2NC6H4)3 (L2) as ligands. These catalysts realize the precise synthesis of π‐conjugated polymers including head‐to‐tail regioregular poly(3‐hexylthiophene) and donor–acceptor type alternating copolymers (DA polymers) through C−H bond activation.