Synthesis and radical polymerization of an optically active monomer derived from cysteine

The synthesis and radical polymerization of N-methacryloyl-S-trityl-L-cysteine methyl ester [MA-C(Trt)-M] were examined. The radical polymerization was carried out at 60°C for 20 h in the presence of 2,2′-azoisobutyronitrile (AIBN) in benzene, PhCl, and N,N-dimethylformamide (DMF) to afford the corresponding polymer with Mn's in the range of 13 200–130 000 in good yields. In the radical copolymerizations of MA-C(Trt)-M with methyl methacrylate and trityl methacrylate, the specific rotations of the copolymers showed maximum values with MA-C(Trt)-M contents of 60 and 80 mol-%, respectively. The polymers were treated with HBr/CH3CO2H (30 wt.-%) to afford the trityl group-free polymers, which were insoluble in solvents due to the oxidative crosslinking reaction between the thiol groups.