INDEX cyclobutanes

Hence, cation-radical copolymerization leads to the formation of a polymer having a lower molecular weight and polydispersity index than the polymer got by cation-radical polymerization— homocyclobutanation. Nevertheless, copolymerization occnrs nnder very mild conditions and is regio-and stereospecihc (Bauld et al. 1998a). This reaction appears to occnr by a step-growth mechanism, rather than the more efficient cation-radical chain mechanism proposed for poly(cyclobutanation). As the authors concluded, the apparent suppression of the chain mechanism is viewed as an inherent problem with the copolymerization format of cation-radical Diels-Alder polymerization. ... 

The final copolymer was obtained in 90% yield it had a molecular weight of 10,800 and a polydispersity index of 2.1. In this case Diels-Alder copolymerization dominates over the cyclobutane homopolymerization of a bi(dienophile). This means that the Diels-Alder addition of the dienophile to the diene is substantially faster than the competing addition of the dienophile cation radical to the neutral dienophile. 

Compendium of Organic Synthetic Methods, Volume 11 contains both functional group transformations and carbon-carbon bond forming reactions from the literature appearing in the years 1999, 2000 and 2001. The classification schemes used for Volumes 6-10 have been continued,-but one new section was added. Section 74G (Cyclobutanations) describes methods that produce cyclobutane rings. As in the past, difunctional compounds appear in Chapter 16. The experienced user of the Compendium will require no special instructions for the use of Volume 11. Author citations and the Author Index have been continued as in Volumes 6-10. 

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