93549-89-4Relevant academic research and scientific papers
Catalytic Carbon-Carbon Bond Activation of Saturated and Unsaturated Carbonyl Compounds via Chelate-Assisted Coupling Reaction with Indoles
Pannilawithana, Nuwan,Yi, Chae S.
, p. 5852 - 5861 (2020/07/21)
The chelate assistance strategy was devised to promote a highly regioselective catalytic C-C bond activation reaction of saturated and unsaturated carbonyl compounds. The cationic Ru-H complex 1 was found to be an effective catalyst for mediating the coupling reaction of 1,2-disubstituted indoles with α,β-unsaturated aldehydes and ketones, in which the regioselective Cα-Cβ activation of the carbonyl substrates has been achieved in forming the 3-alkylindole products. The analogous coupling reaction of indoles with saturated aldehydes and ketones directly led to the Cα-Cβ cleavage of the carbonyl substrates in forming the 3-alkylindole products. The coupling reaction of 1,2-dimethylinole with (E)-3-nonen-2-one and 2-propanol-d8 showed 20-22percent of deuterium incorporation to both α-and β-CH2 of the 3-alkylindole product. The coupling reaction of 1,2-dimethylinole with (E)-3-nonen-2-one exhibited the most significant carbon kinetic isotope effect on the α-carbon of the product (Cα = 1.046). The Hammett plot constructed from the reaction of 1,2-dimethylinole with a series of para-substituted enones p-X-C6H4CH=CHCOCH3 (X = OMe, Me, H, Cl, CF3) showed a modest promotional effect by an electron-donating group (ρ =-0.2 ± 0.1). Several catalytically relevant Ru-H species were detected by NMR from a stoichiometric reaction mixture of the Ru-H complex 1 with 1,2-dimethylindole and (E)-3-nonen-2-one in CD2Cl2. These results support a mechanism of the catalytic coupling reaction via conjugate addition of indoles to enones followed by the C-C bond activation and hydrogenolysis steps.
Conformational Analysis of 1- and 3-Isopropylindoles. A 1H NMR and Molecular Mechanics Study
Nilsson, Ingemar,Berg, Ulf,Sandstroem, Jan
, p. 491 - 500 (2007/10/02)
The conformations of the isopropyl groups in a series of 1- and 3-isopropylindoles have been studied by 1H NMR and molecular mechanics technique.The isopropyl group is shown to assume both syn and an anti conformation, and the equilibrium between these is shown to depend on the steric size of the substituent in position 2.The syn form is relatively more favoured in the 3- than in the 1-isopropylindoles, which can be explained by differences in the lengths of the ring bonds to N-1 and C-3.The energy barriers to syn-anti exchange are 45-46 kJ mol-1 in the 1-iPr compounds when R2=Me or CO2Me.This barrier is lower in the 3-iPr analogues and could only be measured when R1=iPr, R2=Me (35 kJ mol-1).In the 1-iPr compounds a 3-Me group exerts no observable buttressing effect on a 2-Me group, unlike the situation in 1-iso-propylnaphthalenes, where introduction of a 3-Me group leads to an apparent diminution of the steric effect of the 2-Me group ("negative buttressing").In 1-isopropyl-2-methylindole a 3-Br also exerts a negative buttressing effect.
