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Synthesis and electrochemical investigations of piperazines

Categories: Synthesis of N-Heterocycles > Synthesis of Cyclic Amines > Synthesis of piperazines

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EP2084144B1 - Synthesis of piperazines, piperidines …

T1 - Synthesis and evaluation of 4-substituted piperidines and piperazines as balanced affinity μ opioid receptor (MOR) agonist/δ opioid receptor (DOR) antagonist ligands

19/12/2017 · Synthesis of Piperaz..
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The ring-substituted -methylcathinone derivatives are best synthesised by reacting the suitably substituted bromopropiophenone with methylamine; the result is always . In the case of methylone, for example, 2-bromo-3,4-methylenedioxy-propiophenone can be prepared by reacting 3,4-methylenedioxypropiophenone with bromine. These precursor substances are readily available and none of them is under international control. Other methods are required to produce the derivatives, but apart from MDPV, substances such as PPP, MPHP, MOPPP and MDPPP, which briefly appeared in Germany in 2004 (see Table 1), have since been rarely observed.

Scalable Synthesis of Piperazines Enabled by Visible …

Synthesis of piperazines - Organic chemistry
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BZP has been available from retail chemical suppliers and there have been no reports of illicit synthesis. It can be manufactured by reacting piperazine monohydrochloride with benzyl chloride. The latter precursor is readily available, and piperazine monohydrochloride is easily produced from the commercially-available . It is known that 1,4-dibenzylpiperazine (DBZP) can be formed as a side-product in this reaction.

This paper reports the synthesis and characterization of eight series of 1-aryl-4-(2-aryl-1-diazenyl)-piperazines (12 to 19). Several series of these triazenes have been synthesized by the diazotization of a primary arylamine followed by diazonium coupling with a secondary arylpiperazine . The arylpiperazines used in this study are: 1-phenylpiperazine, 1-(4-fluorophenyl-)piperazine, 1-(4-chlorophenyl-)piperazine, 1-(3,4-dichlorophenyl-)piperazine, 1-(2-methylphenyl-)-piperazine, 1-(4-acetophenyl-)-piperazine, 1-(2-pyridyl-)piperazine and 2-cyanophenylpiperazine. These new triazenes (series 12-19) have been identified with a cocktail of contemporary spectroscopic techniques, notably infra-red and nuclear magnetic spectroscopy, supported by high resolution electron ionization mass spectrometry.

Ionic liquid-supported synthesis of piperazine …

Synthesis of piperazines, piperidines and related …
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Piperazine derivatives are usually found in illicit dosage forms as either tablets or capsules, but loose powders also occur. The tablets often carry logos similar to those seen on ‘ecstasy’ tablets. Solutions are encountered less frequently. There are no licensed medicinal products in the EU containing BZP or any of the other substances considered here.

In illicit products, the typical dose of BZP ranges from 50 to 200 mg. In Europe, BZP is often found in combination with other piperazine derivatives (e.g. CPP, TFMPP, DBZP) and less commonly mixed with other well-known substances such as , , ketamine and caffeine. A study in Belgium conducted by the Scientific Institute of Public Health reported that the amount of CPP in tablets in 2008 was between 90 and 110 mg for more than 40 % of cases (of 32 samples). For comparison, when used in psychiatry in challenge tests of the serotonin system, the dose of CPP is typically 50 mg for a 70 kg person.

Lithiation/trapping of N-Boc piperazines and synthesis …
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    Synthesis of Piperazines

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    Synthesis of Piperazines and Thiomorp ho lines by Ozonolysis of Cyclic Olefins and Reductive N-Alkylation

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Synthesis of 2-(4-substituted-1 …

AB - A new method for the synthesis of enantiopure α-substituted piperazines via direct functionalization of the intact piperazine ring is described. The approach utilizes the asymmetric lithiation-substitution of an α-methylbenzyl-functionalized N-Boc piperazine using s-BuLi/(-)-sparteine or (+)-sparteine surrogate and provides access to a range of piperazines (as single stereoisomers). Optimization of the new methodology required a detailed mechanistic study. Surprisingly, it was found that the main culprits affecting the yield and enantioselectivity were the electrophile (the last reagent to be added to the reaction flask) and the distal N-substituent. The mechanistic studies included optimization of lithiation times using in situ IR spectroscopy, identification of a ring-fragmentation of the lithiated piperazines (that could be minimized with sterically hindered N-alkyl groups), and use of a novel "diamine switch" strategy to improve enantioselectivity with certain electrophiles. The methodology was showcased with the preparation of an intermediate for Indinavir synthesis and the stereoselective synthesis of 2,5-trans- and 2,6-trans-piperazines.

Piperazines/chemical synthesis*

N2 - A new method for the synthesis of enantiopure α-substituted piperazines via direct functionalization of the intact piperazine ring is described. The approach utilizes the asymmetric lithiation-substitution of an α-methylbenzyl-functionalized N-Boc piperazine using s-BuLi/(-)-sparteine or (+)-sparteine surrogate and provides access to a range of piperazines (as single stereoisomers). Optimization of the new methodology required a detailed mechanistic study. Surprisingly, it was found that the main culprits affecting the yield and enantioselectivity were the electrophile (the last reagent to be added to the reaction flask) and the distal N-substituent. The mechanistic studies included optimization of lithiation times using in situ IR spectroscopy, identification of a ring-fragmentation of the lithiated piperazines (that could be minimized with sterically hindered N-alkyl groups), and use of a novel "diamine switch" strategy to improve enantioselectivity with certain electrophiles. The methodology was showcased with the preparation of an intermediate for Indinavir synthesis and the stereoselective synthesis of 2,5-trans- and 2,6-trans-piperazines.

Piperazines | Synthesis and Properties

Peters, F.T., Schaefer, S., Staack, R.F., Kraemer, T., Maurer, H.H. (2003), ‘Screening for and validated quantification of amphetamines and of amphetamine- and piperazine-derived designer drugs in human blood plasma by gas chromatography/mass spectrometry’, Journal of Mass Spectrometry, Volume 38, No 6, pp. 659–76.

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