Nuclear Magnetic Resonance Spectroscopic Study on the Structure of Two Stereoisomeric Oxygenated Dimers of 3-Methylindole, 5aβ (H), 11aα (H)-12-Hydroxy-10bβ, 12-dimethyl-5a, 10b, 11a, 12-tetrahydro-6H-oxazolo-[3,2-a : 4,5-b'] diindole

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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 C_<12> atom, on the basis of ^1H and ^<13>C-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^<-1>mol^<-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.
公益社団法人日本薬学会の論文
1985-10-25