432015-53-7Relevant academic research and scientific papers
Diastereodivergent pictet-spengler cyclization of bicyclic N-acyliminium ions: Controlling a quaternary stereocenter
De Carn-Carnavalet, Benot,Krieger, Jean-Philippe,Follas, Benot,Brayer, Jean-Louis,Demoute, Jean-Pierre,Meyer, Christophe,Cossy, Janine
, p. 1273 - 1282 (2015)
The diastereoselectivity of the Pictet-Spengler cyclization of bicyclic N-acyliminium ions that contain a 3-azabicyclo-[n.3.0]alkane core and an electron-rich ?-nucleophilic moiety, such as an indol-2-yl, indol-3-yl, 1-methylpyrrol-2-yl, or 3,5-dimethoxyphenyl group, was examined. The N-acyliminium ions were generated by protonation of the corresponding enamides or hemiaminals, which were derived from imides. Control of the quaternary stereocenter created at the newly formed ring junction was achieved in a diastereodivergent manner by fine-tuning the reaction conditions, which determined whether the reaction proceeded under kinetic or thermodynamic control. Mechanistic studies indicated that a retro-Pictet-Spengler reaction pathway is involved in the equilibration process.
Syntheses of fused tetrahydro-β-carboline analogues through imide carbonyl activation using BBr3: Evidence for the involvement of fused cyclic N-acyliminium ion intermediate
Mangalaraj, Selvaraj,Selvakumar, Jayaraman,Ramanathan, Chinnasamy Ramaraj
, p. 811 - 819 (2015/08/06)
Abstract The fused cyclic N-acyliminium ion generated during the imide carbonyl activation reaction of phenethylphthalimide was confirmed by single crystal X-ray diffraction. The Lewis acid assisted imide carbonyl activation methodology was successfully extended to synthesize fused tetrahydro-β-carboline units from the corresponding N-indolylethylimides. [Figure not available: see fulltext.]
Multimetallic iridium-tin (Ir-Sn3) catalyst in N-acyliminium ion chemistry: Synthesis of 3-substituted isoindolinones via intra- and intermolecular amidoalkylation reaction
Maity, Arnab Kumar,Roy, Sujit
, p. 2627 - 2642 (2014/09/30)
The multimetallic iridium-tritin (Ir-Sn3) complex [Cp*Ir(SnCl3)2{SnCl2(H2O) 2}] (1) proved to be a highly effective catalyst towards C-OH bond activation of γ-hydroxylactams, leading to a nucleophilic substitution reaction known as the α-amidoalkylation reaction. Catalyst 1 can be easily synthesized from the reaction of (pentamethylcyclocyclopentadienyl)iridium dichloride dimer {[Cp*IrCl2]2} and tin(II) dichloride (SnCl2). In terms of catalyst loading, reaction conditions and yields of the product formed, 1 is found to be superior compared to classical Lewis acid catalysts. Different carbon (arenes, heteroarenes, allyltrimethylsilane, 1,3-dicarbonyls) and heteroatom (alcohols, thiols, amides and sulfonamides) nucleophiles have been successfully employed in the intramolecular and intermolecular alkylations, as well as in heterocyclization reactions. In the majority of cases good to excellent yields of 3-substituted isoindolinones and 5-substituted pyrrolidin-2-ones have been obtained. Besides, the reactions are also atom economical and salt free. It is proposed that the multimetallic Ir-Sn3 catalyst behaves as a mild and selective Lewis acid to activate the γ-hydroxylactam towards the formation of the N-acyliminium ion; the latter being trapped by potent nucleophiles leading to the desired products.
