Synthesis of some biologically active substituted thiazole and thiazoline-amino acid derivatives

Synthesis of a series of N-(2-acetylaminothiazole-5-sulphonyl) amino acids (II–VI) and some of their corresponding methyl esters (VII–XI) is described. Coupling of N-tosyl- or N-phthalylamino acid with 2-amino-2-thiazoline using the DCC method furnishes 2-(N-tosyl- or N-phthalylamino acyl)amino-2-thiazolines (XII–XXI). Hydrazinolysis of 2-(N-Pht-L-Phe or N-Pht-L-Ala)amino-2-thiazoline in ethanol afforded 2-(L-Phe or L-Ala) amino-2-thiazoline (XXII and XXIII) respectively. Synthesis of the dipeptide 2-(N-Tos-L-Val-L-Leu) amino-2-thiazoline (XXIV) has been achieved employing the azide method. Sixteen thiazole- and thiazoline-amino acid derivatives were found to be active against a number of microorganisms.