20168-15-4Relevant academic research and scientific papers
Cyclisch gekreuzt-konjugierte Bindungssysteme, 36. Fidecene. Synthesen, Cycloadditionen
Knothe, Lothar,Prinzbach, Horst,Haedicke, Erich
, p. 1656 - 1678 (2007/10/02)
Fidecenes, which in the 5-membered ring are doubly annelated (9/10) or fourfold phenyl-(18) and twofold tert-butyl-substituted (21), as well as the symmetrical (3) and unsymmetrical (25) parent compounds, have been synthesized.The stability of these typically "fulvalenoidal" olefins is determined by the degree of substitution - the derivatives (9, 10, 18, 21) are thus obtained crystalline, the basic frameworks (3, 25) only in dilute solution. 10 reacts via a valence tautomer (31) with maleic anhydride (140 deg C) to give the -adduct 32.Addition of dimethyl acetylenedicarboxylate (80 deg C) occurs in the fulvene portion () giving 33/34.Reaction with tetracyanoethylene (20 deg C) leads regio- and perispecifically to a 1:1-adduct (37), which results, at least formally, from a "symmetry-allowed" ?16s + ?2s>-cycloaddition followed by a suprafacial -H shift.The structure of 37 was verified by an X-ray structure analysis.
