Synthesis and chiral recognition ability of optically active poly{N-[(R)-α-methoxycarbonylbenzyl]methacrylamide} with various tacticities by radical polymerization using Lewis acids

The radical polymerization of an optically active methacrylamide, N-[(R)-α-methoxycarbonylbenzyl]methacrylamide, was carried out in the absence and presence of Lewis acids such as yittribium trifluoromethanesulfonate [Yb(OTf)3] and scandium trifluoromethanesulfonate [Sc(OTf)3]. Catalytic amounts of the Lewis acids significantly affected the stereoregularity of the obtained polymers. The polymerization with Yb(OTf)3 in tetrahydrofuran afforded isotactic polymers (up to mm = 87%), whereas the conventional radical method without the Lewis acid produced polymers rich in syndiotacticity (up to rr = 88%). The radical polymerization in the presence of MgBr2 proceeded in a heterotactic-selective manner (mr = 63%). Thus, the isotactic, syndiotactic, and heterotactic poly(methacrylamide)s were synthesized by the radical processes. The chiral recognition abilities of the obtained optically active poly(methacrylamide)s were affected by the stereoregularity. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3354–3360, 2003