Homopolymerization and [2+4]/[3+2] cycloaddition in the reaction of nitroethylene with vinyl ethers

The reaction of nitroethylene with isobutyl vinyl ether was reinvestigated. In agreement with the report of Kushibiki, Irie, and Hayashi (J Polym Sci Polym Chem Ed 1975, 13, 77)? cycloaddition accompanied the anionic homopoly merization of nitroethylene . However, the cycloadduct was not a cyclobutan e but a bicyclic oxazolidine, in keeping with the more recent report by Den mark and Hurd (J Org Chem 1998, 63, 3045). Cycloaddition accompanied by the anionic homopolymerization of nitroethylene was general for a series of vi nyl and silyl ethers. Mechanistically, the cycloadducts formed by a cis-syn concerted approach of the reactants, whereas a trans-anti approach gave a zwitterionic tetramethylene that initiated anionic homopolymerization. (C) 2001 John Wiley & Sons, Inc.