Stereochemical aspects of the cationic ring-opening polymerization of hetero bicyclic compounds

This paper describes some stereochemical aspects of the cationic ring-opening polymerization of bicyclic acetals and lactones, particularly those having a 6, 8-dioxabicyclo [3. 2. 1] octane skeleton. In the first part, polymerization of bicyclic acetals is discussed, with particular emphasis on cleavages of acetal bonds, configurational changes of acetal carbons, and stereospecificity of polymerization. In the second part, selective formation of cyclic oligoesters of specific ring sizes and unusual isomerization of a polyester chain in the polymerization of 6, 8-dioxabicyclo [3. 2. 1]-octan-7-one are interpreted in terms of polymer chain effects.