Linear-selective cross-coupling polymerization of branched oligothiophene by deprotonative metalation and cross-coupling

Abstract

Brominated oligothiophene with a branched structure was subjected to deprotonative metalation with a bulky magnesium amide chloromagnesium 2,2,6,6-tetramethylpiperidine-2-yl lithium chloride salt (TMPMgCl·LiCl), which is known as the Knochel-Hauser base. The thus metalated oligothiophene was polymerized in the presence of a nickel(II) NHC (N-heterocyclic carbene) complex to afford polymers of M n of 4400 to 44 000, which corresponds well with the monomer feed/catalyst loading ratio. Analysis by MALDI-TOF MS suggests the formation of a linear polymer with oligothiophene as the monomer. Polymerization of 7-mer (7T-Br 4 ) also affords polythiophene of a similar structure.Chart 1 Oligothiophene dendrimers. † Electronic supplementary information (ESI) available: Synthetic procedures and characterisation data. See

Dehalogenative or Deprotonative? The Preparation Pathway to the Organometallic Monomer for Transition‐Metal‐Catalyzed Catalyst‐Transfer‐Type Polymerization of Thiophene Derivatives

“…It was revealed that Murahashi coupling polymerization was successfully achieved by the lithiated species of chlorothiophene, which is prepared by treatment of n BuLi and 5 . Following addition of nickel catalyst 20 underwent polymerization, where use of CPME (cyclopentyl methyl ether) as a solvent was found effective . Block copolymerization was also shown to take place suggesting that the polymerization with organolithium proceeded in a living manner.…”

Diversifying Cross‐Coupling Strategies, Catalysts and Monomers for the Controlled Synthesis of Conjugated Polymers

“…To date, only one NHC ligand has been used in CTP, with 2,6‐( i Pr) 2 C 6 H 3 substituents on the nitrogen atoms of the ring (abbreviated as IPr). Two Ni‐IPr precursors have been employed for the polymerization of thiophene monomers (Figure ) . Interestingly, three different cross coupling methods have been employed with this class of catalyst, demonstrating its broad potential in CTP.…”

“…Interestingly, three different cross coupling methods have been employed with this class of catalyst, demonstrating its broad potential in CTP. It has been explored for Murahashi, Kumada–Corriu and Suzuki–Miyaura coupling . In the recent report employing Ni(IPr)(PPh 3 )Cl 2 for ester functionalized thiophenes, the catalyst displayed some sensitivity to hydrolysis .…”

“…TwoN i-IPr precursors have been employed for the polymerization of thiophene monomers (Figure6). [38,61,[136][137][138][139] Inter- Figure 5. Other classes of nickel catalysts that have been explored in CTP.…”

“…estingly, three different cross coupling methods have been employed with this class of catalyst, demonstrating its broad potential in CTP.I th as been explored for Murahashi, Kumada-Corriu and Suzuki-Miyaura coupling. [38,58,[136][137][138][139] In the recent report employing Ni(IPr)(PPh 3 )Cl 2 for ester functionalized thiophenes, the catalyst displayed some sensitivity to hydrolysis. [38] This has been observed before for Ni-NHC complexes and consequently,s ome caution is necessary when using these precatalysts with H 2 Op resent.…”