Piperazinone Derivatives Research Articles

A single‐step synthesis of 1,3,4,6‐tetraaryl‐5‐aryliminopiperazin‐2‐one

AbstractChemical diversity is a strong driver in drug discovery, and chemical reactions that produce multi‐substituted heterocycles can result in significant chemical diversity. Here, we report a reaction that leads to highly substituted piperazinone derivatives in a single step. This was discovered accidently while reacting phenylglyoxal and anilines under Povarov conditions. We elucidated the structure of the compound formed when 2‐(4‐trifluoromethyphenyl)‐2‐oxoacetaldehyde was reacted with 4‐methoxyaniline as (1,4‐bis(4‐hydroxyphenyl)‐5‐[(4‐hydroxyphenyl)imino]‐3,6‐diphenylpiperazin‐2‐one) (5e). The structure was confirmed after extensive spectral analyses, including correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear single quantum correlation spectroscopy, and heteronuclear multiple‐bond correlation nuclear magnetic resonance spectroscopy, in addition to high‐resolution mass spectrometry. This reaction is unprecedented and can potentially be exploited as a short route to highly diversified heterocycles.

Design, Synthesis and Biological Evaluation of Novel Piperazinone Derivatives as Cytotoxic Agents.

Purpose: In this study, a series of piperazin-2-one derivatives were prepared through bioisosteric substitution of the imidazole ring of L-778,123 (imidazole-containing FTase inhibitor) and rearrangement of groups based on the tipifarnib structure. Final compounds were evaluated for their cytotoxic activities on cancer and normal cell lines by MTT assay. Methods: Methyl α-bromophenylacetic acid and 1-(3-chlorophenyl) piperazin-2-one were synthesized using previously described methods. Methyl 2-(4-chlorophenyl)-2-(4-(3- chlorophenyl)-3-oxopiperazin-1-yl) acetate was prepared by reaction between these two compounds in presence of potassium carbonate. Finally, methoxy group of ester was substituted by various amines such as guanidine, thiourea, urea and hydrazide. The synthesized compounds were tested for their cytotoxicity against colon cancer (HT-29) and lung cancer (A549) cell lines as well as MRC-5 (normal fetal lung fibroblasts) cells as a healthy cell line using MTT colorimetric assay method. Results: Replacement of imidazole moiety with guanidine, thiourea, and hydrazide could increase cytotoxicity toward all three cell lines. Some substituents, such as amine, urea, and hydroxylamine exhibited significant cytotoxicity (<500 µM) but lower than L-778,123 as standard compound. Hydroxyl and methoxy substituents did not show significant cytotoxicity. Imidazole substituent group revealed cytotoxicity similar to L-778,123 All compounds showed lower cytotoxic activity against normal cell lines compared with cancer cell lines. Conclusion: It seems the electron density of substituted groups and rearrangement of groups may significantly increase cytotoxic activity

Enantioselective Synthesis of Pyrrole-Fused Piperazine and Piperazinone Derivatives via Ir-Catalyzed Asymmetric Allylic Amination

Ir-catalyzed intramolecular asymmetric allylic amination reaction of pyrrole derivatives was achieved. The pyrrole-fused piperazine and piperazinone derivatives could be easily accessed from the pyrrole-tethered allylic carbonates in good yields and enantioselectivity (up to 98% ee).

ChemInform Abstract: Intra‐Intermolecular Palladium‐Catalyzed Domino Reactions of Glycine Allylamides for the Synthesis of Diversely Functionalized Piperazinones.

Easily accessible N-tosylglycine allylamides have been converted into diversely functionalized piperazinone derivatives by inter-intramolecular oxidative domino palladium-catalyzed reactions. Aminochlorination and aminoacetoxylation processes were achieved by employing CuCl2 and PhI(OAc)2 as the oxidizing agents to give 5-chloromethyl- and 5-acetoxymethyl-substituted piperazinones, respectively.

Intra‐Intermolecular Palladium‐Catalyzed Domino Reactions of Glycine Allylamides for the Synthesis of Diversely Functionalized Piperazinones

AbstractEasily accessible N‐tosylglycine allylamides have been converted into diversely functionalized piperazinone derivatives by inter‐intramolecular oxidative domino palladium‐catalyzed reactions. Aminochlorination and aminoacetoxylation processes were achieved by employing CuCl2 and PhI(OAc)2 as the oxidizing agents to give 5‐chloromethyl‐ and 5‐acetoxymethyl‐substituted piperazinones, respectively.

Discovery of a Novel Class of Potent HCV NS4B Inhibitors: SAR Studies on Piperazinone Derivatives

HTS screening identified compound 2a (piperazinone derivative) as a low micromolar HCV genotype 1 (GT-1) inhibitor. Resistance mapping studies suggested that this piperazinone chemotype targets the HCV nonstructural protein NS4B. Extensive SAR studies were performed around 2a and the amide function and the C-3/C-6 cis stereochemistry of the piperazinone core were essential for HCV activity. A 10-fold increase in GT-1 potency was observed when the chiral phenylcyclopropyl amide side chain of 2a was replaced with p-fluorophenylisoxazole-carbonyl moiety (67). Replacing the C-6 nonpolar hydrophobic moiety of 67 with a phenyl moiety (95) did not diminish the GT-1 potency. A heterocyclic thiophene moiety (103) and an isoxazole moiety (108) were incorporated as isosteric replacements for the C-6 phenyl moiety (95), resulting in significant improvement in GT-1b and 1a potency. However, the piperazonone class of compounds lacks GT-2 activity and, consequently, were not pursued further into development.

Mechanism insights into an unexpected isomerisation reaction observed during conversion of N-benzyl piperazinones to corresponding N-benzyl thio-piperazinones

An interesting and surprising rearrangement was observed during the reaction of 4-N-benzyl piperazinone derivatives with Lawesson’s reagent as a thionating agent. Investigation into the possible mechanism responsible for these results is reported herein.

DABCO Catalyzed Reaction of Various Nucleophiles with Activated Alkynes (I) Leading to the Formation of Alkenoic Acid Esters, e.g. (III)/(IV), 1,4‐Dioxane (XI), Morpholine (XIII), and Piperazinone Derivatives (XVII).

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

DABCO catalyzed reaction of various nucleophiles with activated alkynes leading to the formation of alkenoic acid esters, 1,4-dioxane, morpholine, and piperazinone derivatives

Abstract The reaction of acids, alcohols, acylamides, 1,2-diols, 1,2-diamines or amino alcohols with activated alkynes catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) was systematically investigated. A series of unsaturated alkenoic acid esters or heterocycles were formed in the reaction of monobasic or dibasic nucleophiles in excellent yields, respectively.

13C NMR spectral assignment of 1,4‐diarylpiperazinones

The piperazinone derivatives have potential application in the pharmaceutical, polymer and textile fields. The present work describes the preparation of a series of new 1,4-diarylsubstituted-2-piperazinones by condensation of substituted N,N'-bis-(2-hydroxyphenyl)-ethylenediamines with glyoxal and the complete (13)C NMR spectral assignment accomplished using APT, HMQC and HMBC techniques. Substituent chemical-shift effects (SCS) were calculated, which showed different values for the lactam- and amine-substituted aromatic rings. The results show that predictions based on SCS effects are not simple for these molecules due to electronic and steric effects. Moreover, in the case of the ortho-substituted derivative 2 g, the NMR spectra reveal a dynamic behavior related to restricted rotation of the phenyl groups (atropisomerism).

3,8-Diazabicyclo[3.2.1]octan-2-one peptide mimetics: synthesis of a conformationally restricted inhibitor of farnesyltransferase.

A new synthesis of the 3,8-diazabicyclo[3.2.1]octan-2-one framework is described. Transannular enolate alkylation of piperazinone derivatives provides a flexible route to highly constrained bicyclic peptidomimetic synthons with substitution at the Calpha position. The chemistry was used to produce a conformationally constrained farnesyltransferase inhibitor, which aided the elucidation of enzyme-bound conformation.

ChemInform Abstract: New Routes to Conformationally Restricted Peptide Building Blocks: A Convenient Preparation of Bicyclic Piperazinone Derivatives.

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New routes to conformationally restricted peptide building blocks: a convenient preparation of bicyclic piperazinone derivatives

A facile route for the synthesis of peptide building blocks that constrain the peptide backbone with a 1,4-diazabicyclo[4.3.0]nonane ring skeleton is reported. The synthesis employed an anodic amide oxidation based approach for generating a functionalized proline derivative, and then utilized the derivative as a general substrate for rapidly assembling the bicyclic ring system.

Analgesic activities of spinal cord substance P antagonists implicate substance P as a neurotransmitter of pain sensation

Substance P (SP) injected into intraspinal (i.s.) spaces caused mice to vigorously scratch and bite their skins in an apparent reaction to a perceived cutaneous sensation. The scratching behavior was similar to the reciprocal hindlimb-scratching syndrome (RHS) described for intracranial (i.c.) SP injections. Radiotracer experiments, as well as potency and latency measurements, demonstrated that SP-induced scratching, whether induced by the i.c. or i.s. route, was due to SP receptor stimulation in the cervicothoracic cord. Similarly, biting was due to SP stimulation of the lumbosacral spinal cord. Mice coated with capsaicin, an irritant chemical, scratched and bit the coated areas in a manner similar to animals injected with i.s. SP. Standard analgesics depressed this scratching behavior elicited by topical capsaicin. Non-analgesic drugs, with the exception of amphetamine, did not affect capsaicin-induced pain. It is concluded that i.s. SP induces a painful sensory experience. Some piperazinone derivatives of substance P's C-terminal hexapeptide are shown to specifically antagonize the scratching induced by i.s. SP with little or no effect on motor behavior. These antagonists depressed scratching elicited by topical capsaicin and were analgesic on the hot-plate test. It is concluded that SP is a natural neurotransmitter for pain and that antagonism of endogenous SP systems causes analgesia.