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Dimerization of 1,6-Diynes with Ionic Liquid Supported Nickel Complexes
A. Goswami, T. Ito, N. Saino, K. Kase, C. Matsuno, S. Okamoto*
Kanagawa University, Yokohama and Kanto Denka Kogyo Co., Ltd., Gunma, Japan
23 March 2009 (online)
NiBr2˙3H2O/Zn with MEEBI catalyzed the dimerization of 1,6-diynes 1 in an ionic liquid (BMI)/toluene biphasic system to afford the corresponding cyclooctatetraenes 2 in up to 81% isolated yield (6 examples, eq. 1). In the absence of an ionic liquid, NiCl2˙6H2O/Zn with DIPIMP promoted the polymerization of 1a to afford poly(1,3-butadienylene) derivative 3a in 54% yield as the main product (eq. 2).