Oxidative Coupling of α,ω - Di(cyclopentadienyl)alkyl-diides


  • Shaochun You
  • Matthias Gubler
  • Markus Neuenschwander Institut für organische Chemie, Universität Bern, Freiestrasse 3, CH-3012 Bern




The CuII-induced oxidative coupling of α,ω-di(cyclopentadienyl)alkyl-diides 6 (n = 2 to 5) – as well as of 1,1,2,2-tetramethyl derivatives 10 and 13 of 6a (n = 2) – has been investigated in view of pertinent questions concerning the 'coupling mode' (e.g. intramolecular vs. intetmolecular coupling), as well as regioselectivity and stereoselectivity of the coupling reaction. As far as the 'coupling mode' is concerned, intermolecular coupling 6 ? 8 strongly dominates over intramolecular coupling 67 (Scheme 2) and the yields of intramolecular coupling products strongly decrease from 7% (7a, n = 2) to 1% (7b, n = 3) to traces (7c, 7d, n = 4,5). It is interesting to note that intramolecular coupling may be considerably enhanced by replacing the H-atoms of the CH2CH2 bridge of 6a (n = 2) by Me groups (see 1011 and 1314 + 15, (Scheme 4). As far as regioselectivity is concerned, intramolecular coupling of 1,2-di(cyclopentadienyl)ethane-diides, 6a, 10, and 13, proceeds as a clean 2,2'-coupling of the cyclopentadiene rings within the limits of NMR identification. Furthermore, the couplings 6a7a and 1011 (as well as 1314 + 15) proceed stereoselectively to give the C2-symmetrical cyclohexanes 7a and 11 with a fixed chair conformation.




How to Cite

S. You, M. Gubler, M. Neuenschwander, Chimia 1991, 45, 387, DOI: 10.2533/chimia.1991.387.