Synthesis and anionic polymerization of isocyanates bearing a carbamate group

New isocyanates bearing the carbamate group, 6-(butoxycarbonylamino)hexyl isocyanate (nBAHI), 6-((S)-(+)-s-butoxycarbonylamino)hexyl isocyanate ((+)-BAHI), and 4-((S)-(+)-s-butoxycarbonylamino)butyl isocyanate ((+)-BABI), were synthesized by reaction of a diisocyanate with an alcohol and polymerized with various anionic initiators in THF at -98 degrees C. The polymerization afforded soluble polymers mainly consisting of a 1-nylon structure. The CD spectral patterns of poly((+)-BAHI) and poly((+)-BABI) were similar to those of optically active helical poly(alkyl isocyanate)s, indicating that the optical rotation of poly((+)-BAHI) and poly((+)-BABI) is determined mainly by the prevailing helicity of the polymer chain. The chiral center in the side group separated by ten or eight sigma-bonds from the polymer main chain appears to influence the helical sense of the polymer through intramolecular effect.