Synthesis of optically active polyurethanes by self-polyaddition of tyrosine-based monomers

The synthesis and self-polyaddition of the optically active monomers I-T(L)-M and I-T(D)-M bearing both isocyanate and hydroxyl groups were examined. I-T(L)-M and I-T(D)-M were synthesized by reactions of L- and D-tyrosine methyl ester, T(L)-M and T(D)-M, with di-tert-butyltricarbonate, respectively. The self-polyaddition of I-T(L)-M and I-T(D)-M proceeded smoothly with triethylamine or tert-butyllithium as the initiator in tetrahydrofuran, affording the optically active linear polyurethanes poly[I-T(L)-M] and poly[I-T(D)-M] with specific head-to-tail structures, where the number-average molecular weights ranged from 10,000 to 20,000 in excellent yields. The optical properties suggested the idea that poly[I-T(L)-M] and poly[I-T(D)-M] should have some higher order structures. (C) 2004 Wiley Periodicals, Inc.