Synthesis of regioisomeric, stereoregular AABB-type polyamides from chiral diamines and diacids derived from natural amino acids

GOMEZ, ROMINA V.; VARELA, OSCAR

TETRAHEDRON-ASYMMETRY

Elsevier Science

Lugar: Norwich, Gran Bretaña; Año: 2007 vol. 18 p. 2190 - 2196

0957-4166

Two regioisomeric and stereoregular AABB-type polyamides have been synthesized using L-glutamic acid (1) and L-alaninol (4) as sources of chirality. From 4, two derivatives of chiral diamines were prepared and regioselectively condensed with pentachlorophenyl 5-oxo-(S)-2-tetrahydrofurancarboxylate (3), derived from 1. Manipulation of functional groups and convenient deprotections led to the ammonium salts of N-[1’-amino-(S)-2’-propyl]- and N-[(S)-2’-amino-1’-propyl]-5-oxo-(S)-2-tetrahydrofurancarboxyamide (11 and 15, respectively), in which the building blocks derived from 1 and 4 are linked through an amido group. Compounds 11 and 15 are, in fact, á,ù-amino acids having amino and lactone groups, and hence activated for the polycondensation. Thus, polymerization of 11 took place under regio- and stereo-control to afford poly[N-(1’-amino-(S)-2’-propyl)-carboxyamido-(S)-2-hydroxypentan-5-oic acid] (16). Similar polycondensation of 15, under the optimized conditions employed for the synthesis of 16, gave the regioisomeric polyamide 17, which exhibited a molecular weight lower than that of 16. The thermal and spectroscopic properties of optically active AABB-polyamides 16 and 17 are described.