2017 Volume 53 Issue 10 Pages 338-347
Novel optically active benzoxazine polymers were synthesized by the Mannich-like condensation polymerization ofD-hydroxyphenylglycine/L-tyrosine hexylamides and methyl esters with 1,3,5-trioxane in CHCl3/toluene = 1/1 and CHCl3/1,4-dioxane = 1/1 at 110 ℃ for 24 h quantitatively. The structures of the benzoxazine polymers were confirmed by the appearanceof IR absorption peaks at 1499 and 917 cm–1 assignable to trisubstituted benzene, and peaks at 1232 and 1117 cm–1 assignableto the oxazine moiety. The higher-order structures of the polymers were analyzed by CD and UV-vis spectroscopies. Thepolymers exhibited circular dichroism（ CD） signals in the region of carbonyl and benzene chromophores in methanol,wherein the patterns and intensities were largely dependent on the substituents（ amide, ester） and the presence/absenceof a methylene spacer between the stereogenic center and the benzene ring. A similar tendency was observed in the CDspectra measured in the solid state. L-Tyrosine-derived amide polymer 3′ exhibited a bisignate carbonyl absorption peak inthe vibration circular dichroism（ VCD） spectrum in CHCl3, indicating the regulated arrangement of the carbonyl groups in aclockwise manner. Conformational analysis suggested that polymer 3′ prefers a conformation which is largely folded ratherthan extended. The ring-opening reaction of the polymers occurred quantitatively at 240–260 ℃.
