Esterification reactions on syndiotactic poly(2-methallyl alcohol). II. Esterification with protected (L)-aspartic and (L)-glutamic acids

The esterification of syndiotactic poly(2-methallyl alcohol) by N^α- and O^ω- protected aspartic and glutamic acids by the DCC/HOBT method is described. Depending on the extent of conversion, either homopolymers or copolymers are obtained. Both homo- and copolymers are characterized by ¹H- and ¹³C-NMR. A second route to the homopolymers has been followed, whereby the poly(2-methallyl alcohol) is first esterified by N^α-protected aspartic or glutamic acid anhydrides and, in a second step, the resulting free carboxyl group on the side chain is esterified by alcohols which are the same as the alcohol moiety of the O^ω-protecting groups. Because the homopolymers were identical to those of the first route, the formation of α-esters with the acid anhydrides is indicated.