Isomerization of polyamide prepared from bicyclic oxalactam

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Abstract
Anionic solution polymerization of bicyclic oxalactam, 8‐oxa‐6‐azabicyclo[3.2.1]octan‐7‐one (abbreviated as BOL), at 25°C yields the polyamide with both carbonyl and imino groups at the axial positions in the tetrahydropyran ring. On the other hand, the polyamide obtained by bulk anionic polymerization of BOL at 100°C has more complicated structures, probably due to the isomerizations and side reactions. The most frequent isomerization of the polyamide was the transfer of the carbonyl group adjacent to the tetrahydropyran ring from the equatorial to the axial position in the presence of base or acid catalyst at 25°C. Mechanisms are discussed from the viewpoint of the characteristic bonds in the polyBOL chain.