Microwave-assisted synthesis and characterization of heterocyclic, and optically active poly(amide-imide)s incorporating L-amino acids

N,N'-Pyromelliticdiimido-di-L-alanine (1), N,N'-pyromelliticdiimido-di-L-phenylalanine (2), and N,N'-pyromelliticdiimido-di-L-leucine (3) were prepared from the reaction of pyromellitic dianhydride with corresponding L-amino acids in a mixture of glacial acetic acid and pyridine solution (3/2 ratio) under refluxing conditions. The microwave-assisted polycondensation of the corresponding diimide-diacyl chloride monomers (5-7) with 4-phenyl-2,6-bis(4-aminophenyl) pyridine (10) or 4-(p-methylthiophenyl)-2,6-bis(4-aminophenyl) pyridine (12) were carried out in a laboratory microwave oven. The resulting poly(amide-imide)s were obtained in quantitative yields, and they showed admirable inherent viscosities (0.12-0.55 dl g(-1)), were soluble in polar aprotic solvents, showed good thermal stability and high optical purity. The synthetic compounds were characterized by IR, MS, H-1 NMR, and C-13 NMR spectroscopy, elemental analysis, and specific rotation. Copyright (C) 2008 John Wiley & Sons, Ltd.