Helix-Sense-Selective Radical Polymerization of Methacrylamides

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In this study, the radical polymerization of N-(triphenylmethyl)methacrylamide (TrMAM) and N-[di(4-butylphenyl)phenylmethyl]-methacrylamide (DBuTrMAM) was carried out in order to attain the helix-sense-selective polymerization leading to optically active polymers. The radical polymerization of TrMAM and DBuTrMAM proceeded in an isotactic-specific manner, and the ^1H NMR spectra of the obtained polymers in D_2SO_4 indicated that the obtained polymers were almost 100% isotactic polymers, which may produce an equimolar mixture of left-and right-handed helices. The poly(DBuTrMAM)s prepared in chiral menthols were optically active, and the polymerization in (+)-menthol and (-)-menthol produced the polymers having the negative and positive specific rotation, respectively. In the circular dichroism (CD) spectra of the poly(DBuTrMAM)s synthesized in menthols at 0℃, the peak patterns suggested that the polymer having an excess single-handed helicity was produced. Although poly(TrMAM)s were insoluble in common organic solvents, the analogous CD patterns were observed in Nujol in for the poly(TrMAM)s obtained in menthols. Triphenylmethyl methacrylate is easily solvolyzed in 10 minutes in methanol-chloroform at 35℃, but TrMAM was quite stable for the solvolysis for a week. Thus, the optically active poly(TrMAM) must afford a much stable chiral stationary phase against alcoholic solvents.