Facile End‐Functionalization of Poly(Quinolylene‐2,3‐Methylene) Using the Terminal Palladium Complex: Thiocarbonylation through Formation of an Acyl Palladium Complex at the Polymer Terminal

Abstract

The end‐functionalization of poly(quinolylene‐2,3‐methylene)s (PQM) via thiocarbonylation is successfully achieved by forming an acyl palladium complex. The terminal palladium complex of the PQMs synthesized by living cyclocopolymerization of o‐allenylaryl isocyanide is quantitatively converted to a tractable acyl palladium complex through the carbon monoxide insertion into a palladium–carbon bond. The resulting acyl palladium complex exhibits high reactivity toward thiols, thereby enabling the introduction of various substituents at the ω‐chain end of PQM by selectively converting them to thioester groups. The one‐pot procedure enables the arbitrary control of both terminal structures of PQMs, including the synthesis of multi‐armed block copolymers and a triblock polymer. Additionally, the resulting thioester groups can serve as reactive sites and be converted into amide groups using amines. The new end‐functionalization method has the potential to be applied not only to the synthesis of PQM but also to other polymerization reactions using transition‐metal complexes, and can lead to a wide range of developments in polymer synthesis.

Direct Introduction of Cysteine Derivatives into the Chain End of Helical Poly(quinoline-2,3-diylmethylene)s: Densely Packed Monolayers on Au Substrates

“…We recently formed an acyl palladium complex by inserting carbon monoxide into the palladium−carbon bond of a palladium complex at the ω-chain end of a PQM (Scheme 1b). 38 The resulting acyl palladium complex was highly reactive toward thiols, thereby enabling the introduction of substituents at the ω-chain end of the PQM by effectively converting them to thioester groups. Leveraging this endfunctionalization method, we focused on the native chemical ligation (NCL) technique, 39 which is widely employed in peptide synthesis.…”

Living Cyclocopolymerization via Alternating Insertion of Alkyl Isocyanide and Allene to the Organonickel Complex

“…Recently, we designed a bifunctional monomer containing isocyano and allenyl groups at adjacent positions on the benzene ring and revealed that cyclocopolymerization proceeds in the presence of an organopalladium complex through completely alternating insertions of isocyanide and allene moieties into the palladium–carbon bonds with perfect head-to-tail selectivity to produce a novel polymer backbone: poly­(quinolylene-2,3-methylene)­s (Scheme b-1) . Furthermore, by selecting the appropriate ligand, cyclocopolymerization can be expanded to living polymerization, which enables precise control of the molar mass and end structure of the resulting polymer. , Additionally, the unique polymer backbone exhibits the formation of specific helical structures , and associated physical properties . These findings are anticipated to propel further advancements and progress in the field of cyclopolymerization.…”

“…21 tion can be expanded to living polymerization, 24 which enables precise control of the molar mass and end structure of the resulting polymer. 25,26 Additionally, the unique polymer backbone exhibits the formation of specific helical structures 27,28 and associated physical properties. 29 These findings are anticipated to propel further advancements and progress in the field of cyclopolymerization.…”