Synthesis of Optically Active Polyguanidines by Polyaddition Reaction of Biscarbodiimides with Chiral Diamines.

Herein, we present the first study on the polyaddition reaction of biscarbodiimides with chiral diamines, which focuses on a definite case using optically active -4a,8a-decahydroquinoxaline and 1,4-phenylenebis(arylcarbodiimide)s, which readily react with each other under ambient and catalyst-free conditions. The specific reactivity allows for facile access to not only the corresponding chiral polyguanidines under balanced stoichiometry but also their oligomeric analogues under imbalanced stoichiometry via a step-by-step procedure. Spectroscopic, chromatographic, and computational characterization of the novel molecular chains containing arrayed guanidines have revealed their structural, optical, and conformational properties as well as the mechanism of polymerization assisted by molecular association. Their potential use as asymmetric catalysts is also described.