Rhodium-Catalyzed Redox-Neutral Cross-Dehydrogenative Alkenylation of Arylhydrazines for Polymer Synthesis

Chu, Benfa; Wu, Xuan; Fu, Ziwen; Wu, Weiping; Wang, Bin; Zhu, Jin

doi:10.1021/acs.macromol.1c01664

“…A Rh-catalyzed redox-neutral CDC polymerization of phenylhydrazine 40 with azobenzene acrylate 41 to furnish the polymer P28 (Scheme 27a) was recently reported. [100] Axially chiral monomers R-42 and S-42 were also used to get the polymers R-P29 and S-P29 with retaining chiral identities (Scheme 27b). N-amino groups in 40 play the roles of both directing group and internal oxidant.…”

Section: Cdc Polymerization Via Arene-alkene Couplingmentioning

confidence: 99%

Cross‐Dehydrogenative Coupling Polymerization via C−H Activation for the Synthesis of Conjugated Polymers

Chakraborty

¹

,

Luscombe

²

2023

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Owing to their versatile (opto)electronic properties, conjugated polymers have found application in several organic electronic devices. Cross‐coupling reactions such as Stille, Suzuki, Kumada couplings, and direct arylation reactions have proved to be effective for their synthesis. More atom‐efficient oxidative direct arylation polymerization has also been reported for making homopolymers. However, growing interest toward donor‐acceptor polymers has led to the recent emergence of cross‐dehydrogenative coupling (CDC) polymerization to synthesize alternating copolymers without any prefunctionalization of monomers. Metal‐catalyzed cross‐coupling of two simple arenes via double C−H activation, or of an arene with an alkene via oxidative Heck‐type reaction have been used so far for CDC polymerization. In this article, we discuss the development of CDC polymerization protocols along with the relevant small molecule CDC reactions for an improved understanding of these reactions.

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“…A Rh‐catalyzed redox‐neutral CDC polymerization of phenylhydrazine 40 with azobenzene acrylate 41 to furnish the polymer P28 (Scheme 27a) was recently reported [100] . Axially chiral monomers R‐ 42 and S‐ 42 were also used to get the polymers R ‐P29 and S ‐P29 with retaining chiral identities (Scheme 27b).…”

Section: Cdc Polymerization Via Arene–alkene Couplingmentioning

confidence: 99%

“…Low optical energy band gaps (1.38 eV and 1.36 eV for P26 A Rh-catalyzed redox-neutral CDC polymerization of phenylhydrazine 40 with azobenzene acrylate 41 to furnish the polymer P28 (Scheme 27a) was recently reported. [100] Axially chiral monomers R-42 and S-42 were also used to get the polymers R-P29 and S-P29 with retaining chiral identities (Scheme 27b). N-amino groups in 40 play the roles of both directing group and internal oxidant.…”

Section: Cdc Polymerization Via Arene-alkene Couplingmentioning

confidence: 99%

Cross‐Dehydrogenative Coupling Polymerization via C−H Activation for the Synthesis of Conjugated Polymers

Chakraborty

¹

,

Luscombe

²

2023

Angewandte Chemie

1

0

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Owing to their versatile (opto)electronic properties, conjugated polymers have found application in several organic electronic devices. Cross‐coupling reactions such as Stille, Suzuki, Kumada couplings, and direct arylation reactions have proved to be effective for their synthesis. More atom‐efficient oxidative direct arylation polymerization has also been reported for making homopolymers. However, growing interest toward donor‐acceptor polymers has led to the recent emergence of cross‐dehydrogenative coupling (CDC) polymerization to synthesize alternating copolymers without any prefunctionalization of monomers. Metal‐catalyzed cross‐coupling of two simple arenes via double C−H activation, or of an arene with an alkene via oxidative Heck‐type reaction have been used so far for CDC polymerization. In this article, we discuss the development of CDC polymerization protocols along with the relevant small molecule CDC reactions for an improved understanding of these reactions.

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“…However, the scope of the alkene partners has been limited largely to electron-deficient olefins and styrene analogues, and also by the high redox potential (Pd(II)/Pd(0) = 0.915 V vs NHE, normal hydrogen electrode), which requires a strong oxidant to drive the catalytic cycle . Moreover, the reaction scope has rarely been extended to efficient polymer synthesis, despite the apparent utility of the conjugated polymer products (Figure b) . In light of our accumulated knowledge on iron-catalyzed C–H activation for making small molecules , and polymers, we considered it feasible to design an iron-catalyzed variant of the FM-type reaction.…”

Section: Introductionmentioning

confidence: 99%

Iron-Catalyzed C–H Activation for Heterocoupling and Copolymerization of Thiophenes with Enamines

Doba

¹

,

Shang

²

,

Nakamura

³

2022

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C–H/C–H coupling via C–H activation provides straightforward synthetic access to the construction of complex π-conjugated organic molecules. The palladium-catalyzed Fujiwara–Moritani (FM) coupling between an arene and an electron-deficient olefin presents an early example but is not applicable to enamines such as N-vinylcarbazoles and N-vinylindoles. We report herein iron-catalyzed C–H/C–H heterocoupling between enamines and thiophenes and its application to copolymerization of bisenamine and bisthiophene using diethyl oxalate as an oxidant and AlMe3 as a base, as a result of our realization that synthetic limitations in oxidative C–H/C–H couplings imposed by the high redox potential of the Pd(II)/Pd(0) catalytic cycle can be circumvented by the use of iron, which has a lower Fe(III)/Fe(I) redox potential. The trisphosphine ligand provides a coordination environment for iron to achieve the reaction’s regio-, stereo-, and chemoselectivity. The reaction includes C–H activation of thiophene via σ-bond metathesis and subsequent enamine C–H cleavage triggered by nucleophilic enamine addition to the Fe(III) center, thereby differing from the FM reaction in mechanism and synthetic scope. The copolymers synthesized by the new reaction possess a new type of enamine-incorporated polymer backbone.

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Rhodium-Catalyzed Redox-Neutral Cross-Dehydrogenative Alkenylation of Arylhydrazines for Polymer Synthesis

Cited by 3 publications

References 51 publications

Cross‐Dehydrogenative Coupling Polymerization via C−H Activation for the Synthesis of Conjugated Polymers

Cross‐Dehydrogenative Coupling Polymerization via C−H Activation for the Synthesis of Conjugated Polymers

Cross‐Dehydrogenative Coupling Polymerization via C−H Activation for the Synthesis of Conjugated Polymers

Iron-Catalyzed C–H Activation for Heterocoupling and Copolymerization of Thiophenes with Enamines

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