Transformation of reactive isochromenylium intermediates to the corresponding storable and stable reagents has been achieved, and a number of isochromenylium tetrafluoroborates (ICTBs, 1) have been conveniently prepared and characterized. Direct metal-free treatment of isochromenylium tetrafluoroborate 1a with olefins afforded a variety of polycyclic frameworks 4 via mild cascade reactions. Starting from the prefunctionalized o-alkynylbenzaldehydes, a one-pot metal-free procedure of intramolecular cascade annulation to 2,3-dihydrophenanthren-4(1H)-one derivatives was also developed.

Abstract1‐Hexene polymerizations catalyzed by α‐diimine nickel complexes after activation with modified methylaluminoxane were performed at various reaction temperatures. Effects of catalyst structure and polymerization temperature on activity and polymer microstructure were evaluated in detail. Bulky catalyst 1b with camphyl backbone exhibited good control ability and greatly enhanced thermal stability to be capable of polymerizing 1‐hexene at 80°C. The poly(1‐hexene)s with long methylene sequences and dominate branches (methyl and butyl) were synthesized using catalyst 1b. Differential scanning calorimetry analysis further confirmed that long polymethylene block ((CH2)n, n > 20) was formed in the poly(1‐hexene)s with melting point of 64°C obtained by catalyst 1b on the basis of initial branched model polyethylene. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

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