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 dlg −1 ), were soluble in polar aprotic solvents, showed good thermal stability and high optical purity. The synthetic compounds were characterized by IR, MS, 1 H NMR, and 13 C NMR spectroscopy, elemental analysis, and specific rotation. Copyright © 2008 John Wiley & Sons, Ltd.