1985 年 33 巻 10 号 p. 4167-4174
The oxygenated dimer (2a) of 3-methylindole, which was isolated from the reaction mixture obtained by oxygenation of 3-methylindole in the presence of N, N'-(cis-1, 2-cyclohexylene) bis (3-tert-butylsalicylideneaminato) cobalt (II) in chloroform, was shown to be the stereoisomer of 5aβ (H), 11aα (H)-12β-hydroxy-10bβ, 12α-dimethyl-5a, 10b, 11a, 12-tetrahydro-6H-oxazolo [3, 2a : 4, 5-b'] diindole (1a) with inverted configuration at the C12 atom, on the basis of 1H and 13C-nuclear magnetic resonance (NMR) spectroscopic and chemical evidence. Kinetic parameters of restricted rotation about the amide bond in N-acetylated derivatives of 1a and 2a calculated from their dynamic NMR spectra were ΔH≐̸298=20.2±0.2 and ΔS≐̸298=+7.8±0.5 for the former, and ΔH≐̸298=19.7±0.2kcal mol-1 and ΔS≐̸298=+5.9±0.6cal K-1mol-1 for the latter. Acid decomposition of both dimers, 1a and 2a, afforded 3, 3'-dimethyl-1-(2'-indolyl)-oxindole, resulting from ring cleavage at the ether bond followed by dehydration.
