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Ring‐Opening Copolymerization of 2‐Aryl‐1‐methylenecyclopropanes with Carbon Monoxide Initiated by Pd–bpy Complexes
Author(s) -
Kim Sunwook,
Takeuchi Daisuke,
Osakada Kohtaro
Publication year - 2003
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200390035
Subject(s) - chemistry , aryl , monomer , alkyl , copolymer , ring (chemistry) , polymer chemistry , carbon monoxide , polymerization , palladium , catalysis , medicinal chemistry , ring opening polymerization , polymer , stereochemistry , organic chemistry
[PdCl(Me)(bpy)] and a mixture of the complex with cocatalysts; NaBARF (BARF = [B{C 6 H 3 (CF 3 ) 2 ‐3,5} 4 ] − ), NaBF 4 , AgBARF, AgBF 4 , and AgOTf, catalyze the copolymerization of 2‐phenyl‐1‐methylenecyclopropane with carbon monoxide to produce a new polyketone accompanied by ring opening of the monomer. 1 H and 13 C{ 1 H} NMR spectra indicate that the polymers have two isomeric repeating units in which the phenyl substituents occupy different positions. The molecular weights of the polyketones formed by the reactions with a [Pd]/[cocatalyst]/[2‐phenyl‐1‐methyleneyclopropane] ratio of 1:3:70 are in the range of M n = 13 100–86 000. The polymer obtained by the reaction promoted by [PdCl(Me)(bpy)]/MBARF, where M = Ag or Na, shows a narrow molecular weight distribution, M w / M n = 1.44 and 1.59, respectively. The catalysis is effective also for the ring‐opening copolymerization of 2‐aryl‐1‐methylenecyclopropanes bearing Me and F substituents on the phenyl ring. Isotope‐labeled experiments revealed the mechanism of the polymerization, which involves a 1,2‐insertion of the monomer into the Pd–acyl bond to produce a cyclopropylmethyl palladium intermediate, and subsequent β ‐alkyl elimination to give the Pd–alkyl complex.