Zwitterion Cycloadditions and Free-Radical Polymerizations of p-(Dimethylamino)styrene with Tris- and Tetrakis(carbomethoxy)ethylenes

Article abstract of DOI:10.1021/jo01293a015

Tris- and tetrakis(carbomethoxy)ethylenes reacted with p-(dimethylamino)styrene to form cyclobutane cycloadducts.The reaction proceeded faster in polar solvents than in nonpolar solvents.This evidence supports a zwitterion intermediate in the cycloaddition reaction, but an intermediate could not be trapped with methanol, acetonitrile, or phenyl isocyanate.The cycloaddition reaction was not influenced by UV irradiation, radical inhibitors, or the one-electron oxidant ferric nitrate.These results are evidence against a possible cation-radical intermediate.Free-radical-initiated copolymerization occurred between tris- but not tetrakis(carboxymethoxy)ethylene and p-(dimethylamino)styrene to yield approximately alternating copolymers.These data are completely analogous to those obtained with other electron-rich styrenes and electrophilic trisubstituted ethylenes.