Mg. Ophoff et al., ESTERIFICATION REACTIONS ON SYNDIOTACTIC POLY(2-METHALLYL ALCOHOL) .5. HOMOPOLYMERS OF 2-METHALLYL-(L)-DIPEPTIDATES AND DIPEPTIDES CLEAVED FROM THEM, Journal of polymer science. Part A, Polymer chemistry, 33(5), 1995, pp. 815-828
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.