Asymmetric anionic polymerizations of 7-cyano-7-alkoxycarbonyl-1,4-benzoquinone methides

Asymmetric anionic polymerizations of 7-cyano-7-alkoxycarbonyl-1,4-benzoquinone methides (1) with various alkoxy groups were performed using chiral initiators such as lithium isopropylphenoxide (iPrPhOLi)/(S)-2,2'-isopropylidene-bis(4-phenyl-2-oxazoline) ((-)-PhBox) and lithium isopropylphenoxide (iPrPhOLi)/(-)-sparteine ((-)-Sp) to investigate the effect of the alkoxy groups of alkoxycarbonyl substituent in the monomers 1 and chiral ligands of chiral initiators on the control of chiral center in the formation of polymers. Molar optical rotation values of the polymers were significantly dependent upon alkoxy groups, and the polymers with higher molar optical rotation were obtained in monomers with primary alkoxy groups. The asymmetric anionic oligomerizations of the quinone methides having methoxy(1a), ethoxy(1b), and n-propoxy(1c) groups with chiral initiators were carried out. Both 1-mers and 2-mers were isolated and their optical resolutions were performed to determine the extent of stereocontrol. High stereoselectivity was observed at the propagation reaction, but not at the initiation reaction. The effect of the counterion on the control of chiral center in the formation of the polymer was investigated in the asymmetric anionic polymerizations of 1b with iPrPhOM(M = Li, Na, K)/(-)-Sp and iPrPhOM(M = Li, Na, K)/(-)-PhBox initiators and discussed. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 50: 466-479, 2012