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Cyclopolymerization of N,N‐ Dipropargyl‐3,4‐dialkoxyanilines Using Schrock and Grubbs‐Hoveyda Initiators: Influence of Initiator Structure on the Mode of Insertion
Author(s) -
Buchmeiser Michael R.,
Schmidt Christian,
Wang Dongren
Publication year - 2011
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.201100211
Subject(s) - polymer chemistry , monomer , chemistry , catalysis , polymer , selectivity , organic chemistry
4‐Aza‐1,6‐heptadiynes are cyclopolymerized using a series of Schrock‐ and Grubbs‐Hoveyda‐type initiators. It is found that with Schrock initiators (i) the concept of large and small alkoxides applies, (ii) the size of the substituents in the 2‐ and 6‐position of the arylimido ligand play a significant role in the mode of insertion, (iii) addition of a base such as quinuclidine to an initiator favors α ‐insertion and thus five‐membered repeat units, and (iv) coordination of the monomer's nitrogen lone pair during the catalytic cycle favors β ‐ over α ‐insertion and thus results in polymers with a high fraction of six‐membered rings. Using modified Grubbs‐Hoveyda initiators, cyclopolymerization of the azaheptadiynes lead to the formation of poly(ene)s containing 24–51% six‐membered repeat units, thus representing the first Ru‐alkylidene‐triggered cyclopolymerization of 1,6‐heptadiynes with significant β ‐selectivity.