93334-99-7Relevant academic research and scientific papers
Iridium-catalyzed condensation of amines and vicinal diols to substituted piperazines
Lorentz-Petersen, Linda L. R.,Nordstrom, Lars Ulrik,Madsen, Robert
, p. 6752 - 6759 (2012)
A straightforward procedure is described for the synthesis of piperazines from amines and 1,2-diols. The heterocyclization is catalyzed by [Cp*IrCl2]2 and sodium hydrogen carbonate and can be achieved with either toluene or water as solvent. The transformation does not require any stoichiometric additives and only produces water as the byproduct. The reaction can be performed between a 1,2-diamine and a 1,2-diol or by a double condensation between a primary alkylamine and a 1,2-diol. At least one substituent is required on the piperazine ring to achieve the cyclization in good yield. The mechanism is believed to involve dehydrogenation of the 1,2-diol to the α-hydroxy aldehyde, which condenses with the amine to form the α-hydroxy imine. The latter rearranges to the corresponding α-amino carbonyl compound, which then reacts with another amine followed by reduction of the resulting imine. Piperazines are prepared by [Cp*IrCl 2]2-catalyzed heterocyclization of 1,2-diols with either 1,2-diamines or primary alkylamines. The reaction is performed in toluene or water and requires no stoichiometric additive. The key step in the mechanism is believed to be the isomerization of an α-hydroxy imine to the corresponding α-amino carbonyl compound. Copyright
METHOD FOR PRODUCING OPTICALLY ACTIVE 2-METHYLPIPERAZINE
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Paragraph 0064, (2017/01/26)
PROBLEM TO BE SOLVED: To provide a method capable of industrially obtaining an optically active 2-methylpiperazine which is easy in handling and has good properties, instead of the isolation method of an optically active 2-methylpiperazine by conventional distillation. SOLUTION: There is provided a method for producing an optically active 2-methylpiperazine by adding a solvent to a solution of an optically active 2-methylpiperazine, followed by solvent substitution and crystallization to obtain crystals of the optically active 2-methylpiperazine. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
The Absolute Configurations of (+)- and (-)-2-Methylpiperazines and their N-Methyl Derivatives.
Armarego, Wilfred L. F.,Schou, Henning,Waring, Paul
, p. 1951 - 1966 (2007/10/02)
S(-)-2-Methylpiperazinium dichloride was prepared by reduction of S(-)-3-methyl-2,5-dioxopiperazine (from glycyl-S-alanine) which established its absolute configuration.This dichloride and its enantiomer, R(+)-2-methylpiperazinium dichloride, were obtained in less optically pure forms by recrystallization of the diastereomeric RS-2-methylpiperazinium 2R,3R-di-O-benzoyltartrate salts followed by decomposition with a base.They were converted into S(+)- and R(-)-1,2,4-trimethylpiperazinium dichloride, S(+)- and R(-)-1,2,4,4-tetramethylpiperazinium iodide and S(+)- and R(-)-1,1,2,4,4-pentamethylpiperazinium diiodide.
