ESTERIFICATION REACTIONS ON SYNDIOTACTIC POLY(2-METHALLYL ALCOHOL) .5. HOMOPOLYMERS OF 2-METHALLYL-(L)-DIPEPTIDATES AND DIPEPTIDES CLEAVED FROM THEM

Syndiotactic poly(2-methallyl alcohol) (sPMA) is esterified with N-alp ha-protected (L)-alpha-amino acids by the DCC/HOBT method. The resulti ng polymer is deprotected by HBr/glacial acetic acid. A second N-alpha -protected (L)-alpha-amino acid is condensed to the free alpha-NH2 of the amino acid already bound to the sPMA by a water-soluble carbodiimi de in mixed aqueous/organic solution. The formed N-alpha-protected dip eptide polymers were hydrazinolized to yield the N-alpha-protected dip eptide hydrazides. Alternatively, the dipeptidate polymers were N-alph a-deprotected and then hydrolyzed by aqueous KOH at pH = 11.0 to yield the deprotected dipeptides. All polymers and the dipeptides were char acterized by H-1- and C-13-NMR and the water-soluble N-alpha-deprotect ed polymers in addition by potentiometry. The synthetic procedures ope n a path to defined tactic polymers with chiral oligopeptide side chai ns and, after their cleavage, also to oligopeptides. During synthesis, the oligopeptide is bound to a dissolved polymer chain of relatively extended macroconformation which facilitates both the accessibility an d reactivity of the reaction centers as well as the precipitation and filtration after each synthesis step. (C) 1995 John Wiley & Sons, Inc.