Synthesis and Dynamic Properties of Cyclooctatetraenyl(dipropyl)borane Mikhail E. Gurskii, a Ilya D. Gridnev, a Alexei V. Buevich, a Tamara V. Potapova, a Vadim I. Mstislavsky, a Anatoly O. Krasavin b and Yurii N. Bubnov* a a N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow, Russian Federation. Fax: +7 095 135 5328 b Higher Chemical College of the Russian Academy of Sciences, 125820 Moscow, Russian Federation. Cyclooctatetraenyldipropylborane 4 has been synthesized in 47% yield; activation parameters for bond shifting in 4 determined by lineshape analysis of the 13 C NMR spectra are DG  j (298) = 67.70.1 kJ mol ±1 ; DH  j = 58.10.8 kJ mol ±1 ; DS  j = ±325 kJ mol ±1 K ±1 . For the last 83 years, since it was first synthesized, cyclooctatetraene 1 has been the object of extensive investiga- tions. 2,3 This compound is a central point in the solution of many fundamental problems of chemistry, i.e. aromaticity and anti-aromaticity, valent tautomerism, dynamic stereo- chemistry, etc. Moreover, cyclooctatetraene has proved to possess great synthetic potential; use of 1 as a classic ligand in the synthetic chemistry of transition metals clusters, 2 as a starting compound in the synthesis of various polyunsaturated molecules and macrocycles, 2 or as a building block for obtaining stereoregular polyacetylenes 4 can be mentioned. In the course of our study of polyunsaturated organo- Mendeleev Commun., 1994, 4(6), 221–223 Mendeleev Communications – 221 –