Polymerization of Diazoacetates Initiated by the Pd(N‑arylmaleimide)/NaBPh4 System: Maleimide Insertion into a Pd–C Bond Preceding to Initiation Leading to Efficient α‑Chain-End Functionalization of Poly(alkoxycarbonylmethylene)s

Three new N-arylmaleimide-based Pd(0) complexes [Pd­(N-phenylmaleimide)2(2,5-norbornadiene) (1), Pd­(N-2,6-difluorophenylmaleimide)2(2,5-norbornadiene) (2), and Pd­(N-2,6-difluorophenylmaleimide)2(dibenzylideneacetone) (3)] were prepared and used as an initiator in conjunction with NaBPh4 [Pd­(N-ary...

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Published in:Macromolecules 2022-07, Vol.55 (14), p.5985-5996
Main Authors: Shimomoto, Hiroaki, Hayashi, Hinano, Aramasu, Kyoka, Itoh, Tomomichi, Ihara, Eiji
Format: Article
Language:English
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Summary:Three new N-arylmaleimide-based Pd(0) complexes [Pd­(N-phenylmaleimide)2(2,5-norbornadiene) (1), Pd­(N-2,6-difluorophenylmaleimide)2(2,5-norbornadiene) (2), and Pd­(N-2,6-difluorophenylmaleimide)2(dibenzylideneacetone) (3)] were prepared and used as an initiator in conjunction with NaBPh4 [Pd­(N-arylmaleimide)/NaBPh4 system] for polymerization of diazoacetates. The Pd­(N-arylmaleimide)/NaBPh4 system polymerized a series of diazoacetates (ethyl, benzyl, and cyclohexyl diazoacetates) to yield polymers in moderate to good yield, particularly showing a high activity for cyclohexyl diazoacetate. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis and other experimental observations revealed the incorporation of one N-arylmaleimide molecule coordinated on the Pd center into the α-chain end of the polymers obtained with the initiating system, indicating that the initiating species of the polymerization was generated by insertion of N-arylmaleimide into a Pd–Ph linkage, which was first formed by the reaction of the Pd(0) complex with NaBPh4, and that the initiating system would enable syntheses of α-chain-end-functionalized poly­(alkoxycarbonylmethylene)­s.
ISSN:0024-9297
1520-5835
DOI:10.1021/acs.macromol.2c00508