Synthesis of chiral polyhydroxy polyamides having chains of defined regio and stereoregularity

1,6-Diaminohexane and a 2-(S)-hydroxypentanedioic acid 5,2-lactone derivati ve (3) were polycondensed to afford an aregic polyamide 4. A chiral monomer (5) having a a-fold axis of symmetry was chemoselectively constructed from 3, and upon polymerization with the diamine led to an AABB-type polyamide having a syndioregic orientation of the hydroxyl substituents. The analogou s isoregic polyamide 11 was also prepared. The three polymers had the same basic structure, but they differ in their regio and stereoregularity. These polyamides, which displayed optical activity, were characterized by IR and H-1 and C-13 NMR, and their molecular weights were estimated by GPC, visco simetry, and matrix-assited ultraviolet laser desorption/ionization time-of -flight mass spectrometry (UV-MALDI-TOF MS). This technique was particularl y convenient to confirm the repeat units and to detect the functional group s at both ends of the chains. In accordance with their growth processes pol yamides 11 and 12 showed the typical UV-MALDI-TOF spectrum for homopolymeri zation, and polyamides 4 and 6 showed those corresponding to growing by cop olymerization. Besides, in agreement with their stereoregularity, polyamide s 6 and 11 showed better crystalline properties than those of 4.