Ruthenium(II)-Catalyzed Isomer-Selective Cyclization of 1,6-Dienes Leading to exo-Methylenecyclopentanes: Unprecedented Cycloisomerization Mechanism Involving Ruthenacyclopentane(hydrido) Intermediate
Yoshihiko Yamamoto, Yu-ichiro Nakagai, Naoki Ohkoshi and Kenji Itoh*
*Department of Molecular Design and Engineering, and Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Chikusa, Nagoya 464-8603, Japan
Y. Yamamoto, Y.-i. Nakagai, N. Ohkoshi, K. Itoh, J. Am. Chem. Soc., 2001, 123, 6372-6380.
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Ruthenium(II) complexes catalyze an efficient conversion of 1,6-dienes into the corresponding exo-methylenecyclopentanes in very good yields with good isomer purity in i-PrOH at 90 °C. In contrast, a Ru(0) complex, (C6Me6)Ru(cod), catalyzed the cycloisomerization only in 1,2-dichloroethane.
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