Reactivity of 2-Methylene-1,3-dicarbonyl Compounds. Stereoselective and Asymmetric Diels-Alder Reactions.
The Diels-Alder reaction of 1,1-dicarbonylethenes 1 with dienes was investigated. The adduct of the reaction of 1, whose two carbonyl groups were different, with cyclopentadiene showed moderate stereoselectivity and this was explained by FMO theory. However, in the Lewis acid-catalyzed addition, the reaction proceeded with high stereoselectivity to give the exo adduct 3x. This might be due to steric hindrance because the benzene ring cannot orient in the plane of the conjugated system in the metal-chelated enedione 6. Applying this principle to (1'R,2'S,5'R)-5-methyl-2-(1-methyl-1-phenylethyl)cyclohexyl 2-benzoylacrylate (1d), we achieved a diastereomeric Diels-Alder reaction to afford 3x-R, whose structure was confirmed by the X-ray crystal analysis.
Yamauchi
Masashige
M
Faculty of Pharmaceutical Sciences, Josai University, Keyakidai, Sakado, Saitama 350-02, Japan, and Organic Chemistry Research Laboratory, Tanabe Seiyaku Co Ltd., Kawaguchi, Toda, Saitama 335, Japan.
Honda
Yuko
Y
Matsuki
Nobuhiko
N
Watanabe
Toshio
T
Date
Kimimasa
K
Hiramatsu
Hajime
H