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Norbornadiene
About: Norbornadiene is a research topic. Over the lifetime, 2389 publications have been published within this topic receiving 38603 citations.
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33 citations
TL;DR: Employing a series of norbornadiene derivatives as substrates, the effects of various substituents on the Ir-catalyzed asymmetric [2 + 2] cycloaddition reactions with arylacetylenes were studied and it was found that the atom forming the short bridge chain had a great effect on the enantioselectivity of the reaction.
Abstract: Employing a series of norbornadiene derivatives as substrates, the effects of various substituents on the Ir-catalyzed asymmetric [2 + 2] cycloaddition reactions with arylacetylenes were studied. It was found that the atom forming the short bridge chain had a great effect on the enantioselectivity of the reaction. Heteroatoms, such as oxygen and nitrogen, always resulted in excellent enantioselectivity. However, carbon atoms could decrease the enantioselective control ability of the catalyst over the reaction. The groups on the unreacted carbon–carbon double bond were found to have but a little effect on the reaction. Based on the results of the experiments, a mechanism was also hypothesized for the reaction.
33 citations
33 citations
33 citations
TL;DR: In this paper, a columnar assembly of polyacetylene esters was characterized using 1 H and 13 C NMR spectroscopy, X-ray diffraction, and atomic force microscope methods.
Abstract: Alkyl propiolates: HC≡CCOOn-C m H 2m+1 (m = 2∼4), acetylene esters were polymerized with a [Rh(norbornadiene)Cl] 2 catalyst in methanol as the polymerization solvent to produce poly(n-alkyl propiolate)s, PAPAs, called polyacetylene esters, in relatively high yields. The resulting PAPAs were characterized in detail using 1 H and 13 C NMR spectroscopy, X-ray diffraction, and atomic force microscope methods. The data showed that the resulting polymers selectively have cis-transoid form. The cis-transoid isomer is not amorphous but holds a pseudohexagonal structure called a columnar assembly the diameter of which agrees with those estimated by the semiempirical calculation method (AM1). The crystalline ratios of the columnar assemblies were also estimated to be ca. 60∼70%. In the case of poly(ethyl propiolate), PEPA, the crystalline size was found to approximately agree with that estimated from the AFM images of the cast film of PEPA.
33 citations