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Controlled Cyclotrimerization in Hyperbranched Polymer Synthesis

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journal contribution
posted on 21.11.2001, 00:00 authored by Masayoshi Higuchi, Hirohiko Kanazawa, Masanori Tsuruta, Kimihisa Yamamoto
Cyclization in hyperbranched polymer synthesis was first controlled on the basis of a steric effect using a Lewis acid with a bulky ligand. Only phenylazomethine oligomers having a cyclic structure were formed during the polymerization of 4,4‘-diaminobenzophenone in the presence of TiCl4(THF)2 as a Lewis acid with bulky ligands. The structure of a cavity in an isolated cyclic oligomer was determined by X-ray crystal analysis. Controlled cyclization is applied for hyperbranched polymer synthesis, and a novel dendrimer with a cyclic structure was quantitatively obtained via controlled cyclization on the basis of a steric effect using a monomer with a bulky dendron.