- Structure-Activity Relationship Studies on Oxazolo[3,4- a]pyrazine Derivatives Leading to the Discovery of a Novel Neuropeptide S Receptor Antagonist with Potent in Vivo Activity
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Neuropeptide S modulates important neurobiological functions including locomotion, anxiety, and drug abuse through interaction with its G protein-coupled receptor known as neuropeptide S receptor (NPSR). NPSR antagonists are potentially useful for the treatment of substance abuse disorders against which there is an urgent need for new effective therapeutic approaches. Potent NPSR antagonists in vitro have been discovered which, however, require further optimization of their in vivo pharmacological profile. This work describes a new series of NPSR antagonists of the oxazolo[3,4-a]pyrazine class. The guanidine derivative 16 exhibited nanomolar activity in vitro and 5-fold improved potency in vivo compared to SHA-68, a reference pharmacological tool in this field. Compound 16 can be considered a new tool for research studies on the translational potential of the NPSergic system. An in-depth molecular modeling investigation was also performed to gain new insights into the observed structure-activity relationships and provide an updated model of ligand/NPSR interactions.
- Albanese, Valentina,Ruzza, Chiara,Marzola, Erika,Bernardi, Tatiana,Fabbri, Martina,Fantinati, Anna,Trapella, Claudio,Reinscheid, Rainer K.,Ferrari, Federica,Sturaro, Chiara,Calò, Girolamo,Amendola, Giorgio,Cosconati, Sandro,Pacifico, Salvatore,Guerrini, Remo,Preti, Delia
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p. 4089 - 4108
(2021/04/12)
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- Highly efficient enantioselective synthesis of 1,3-disubstituted 2,5-diketopiperazine derivatives via microwave irradiation
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Chiral 2,5-diketopiperazine (2,5-DKP) derivatives have a broad range of biological activities in the medicinal field. The synthetic protocols of 1,3-disubstituted 2,5-DKPs via base-catalyzed cyclization of chloroacetamide have been reported. However, there are several drawbacks, such as an overly long reaction time, low to moderate yield, and racemization of the products. The sequence modified herein of 1,3-disubstituted 2,5-DKPs involves microwave-assisted cyclization. It increases yields and reduces reaction time. Furthermore, employing N-PMB protection prevents racemization, which frequently occurs in the base-catalyzed cyclization reaction. Consequently, the rapid synthetic method of enantiomerically pure 1,3-disubstituted 2,5-DKPs via microwave reaction was established successfully.
- Han, Si Yeon,Gong, Young-Dae
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p. 3426 - 3434
(2019/11/03)
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- Efficient one-pot synthesis of enantiomerically pure: N -protected-α-substituted piperazines from readily available α-amino acids
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A new pathway towards enantiomerically pure 3-substituted piperazines, bearing a benzyl protecting group, has been developed in good overall yields (83-92%), starting from commercially available N-protected amino acids. The methodology represents an efficient and simple one-pot procedure, employing a synthetic sequence consisting of an Ugi-4 component reaction, a Boc-deprotection, an intramolecular cyclisation reaction and a final reduction (UDCR). From the benzyl protected precursors, the 2-substituted piperazines bearing a Boc-protecting group could consequently also be obtained via a simple protection and deprotection step of the corresponding piperazines. The practical utility of this methodology was demonstrated for chiral drug synthesis.
- Jida, Mouhamad,Ballet, Steven
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supporting information
p. 1595 - 1599
(2018/02/09)
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- Enantiomerically pure piperazines via NaBH4/I2reduction of cyclic amides
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Enantiomerically pure (3S,7R,8aS)-3-phenyloctahydropyrrolo[1,2-a]pyrazine-7-ol, (3S,7R,8aS)-3-methyl octahydropyrrolo[1,2-a]pyrazine-7-ol, (3S,7R,8aS)-3-isopropyloctahydropyrrolo[1,2-a]pyrazine-7-ol and (3S,7R,8aS)-3-isobutyloctahydropyrrolo[1,2-a]pyrazine-7-ol 16d were synthesized via preparation of the corresponding cyclic amides from enantiomerically pure L-proline and hydroxyproline derivatives followed by reduction using sodium borohydride-iodine.
- Harish, Vagala,Periasamy, Mariappan
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p. 175 - 180
(2017/01/11)
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- Synthesis and SAR of potent and selective tetrahydropyrazinoisoquinolinone 5-HT2C receptor agonists
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The 5-HT2C receptor has been implicated as a critical regulator of appetite. Small molecule activation of the 5-HT2C receptor has been shown to affect food intake and regulate body weight gain in rodent models and more recently in hu
- Zhao, Guohua,Kwon, Chet,Bisaha, Sharon N.,Stein, Philip D.,Rossi, Karen A.,Cao, Xueying,Ung, Thao,Wu, Ginger,Hung, Chen-Pin,Malmstrom, Sarah E.,Zhang, Ge,Qu, Qinling,Gan, Jinping,Keim, William J.,Cullen, Mary Jane,Rohrbach, Kenneth W.,Devenny, James,Pelleymounter, Mary Ann,Miller, Keith J.,Robl, Jeffrey A.
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p. 3914 - 3919
(2013/07/27)
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- Synthesis and structure of 1,4-dipiperazino benzenes: Chiral terphenyl-type peptide helix mimetics
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(Chemical Equation Presented) The terphenyl structure has been proven to be an ideal scaffold mimicking side-chain functionalities of peptidic α-helices. The synthesis of 1,4-dipiperazino benzenes, using stepwise transition metal-catalyzed N-arylation of chiral piperazines to a central benzene core is reported. The structure determination by X-ray crystallography reveals a geometrical arrangement of the hydrophobic side chains resembling the orientation of key i, i + 3, and i + 7 positions in a peptidic α-helix or in terphenyl helix mimetics.
- Maity, Prantik,Koenig, Burkhard
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supporting information; experimental part
p. 1473 - 1476
(2009/04/10)
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- ROCK INHIBITORS AND USES THEREOF
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The subject invention concerns compositions and methods for blocking cancer cell growth or proliferation and/or inducing cancer cell death. Compositions of the present invention are compounds that inhibit Rho - protein associated kinase function. Compounds of the invention include piperazinyl pyridines, piperazinylmethyl pyridines, piperazinyl ureas and carbamates, piperazinyl pyridines and quinoilines (including isoquinliones) as well as piperazinyl (including piperazinylmethyl) pyridines and quinolines (including isoquinolines). Compounds of the invention disrupt Rho-kinase activation and function and significantly inhibit tumor cell growth and induce tumor cell death.
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Page/Page column 15; 17
(2008/12/07)
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- Synthesis of 2,6-bridged piperazine-3-ones by N-acyliminium ion chemistry
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Several 2-substituted and 2,5-disubstituted piperazine-3,6-diones were synthesized starting from readily available α-amino acids. After activation of a lactam carbonyl via introduction of a methoxycarbonyl group onto nitrogen, this carbonyl was selectively reduced. Treatment of the resulting urethane with protic acid generated the corresponding N-acyliminium ion, which was trapped by a nucleophilic C2-side chain to provide 2,6-bridged piperazine-3-ones. Several aromatic, heteroaromatic, and nonaromatic side chains were used as π-nucleophiles. In addition, the effect of the presence of a C5-methyl group on the stereochemical outcome of the cyclization was examined.
- Veerman, Johan J. N.,Bon, Robin S.,Hue, Bui T. B.,Girones, Daniel,Rutjes, Floris P. J. T.,Van Maarseveen, Jan H.,Hiemstra, Henk
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p. 4486 - 4494
(2007/10/03)
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- Exploring the structure-activity relationships of [1-(4-(4- tert-butyl-3'-hydroxy)benzhydryl-4-benzylpiperazine] (SL-3111), a high-affinity and selective δ-opioid receptor nonpeptide agonist ligand
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SL-3111 [1-(4-tert-butyl-3'-hydroxy)benzhydryl-4- benzylpiperazine] is a de novo designed, high-affinity and selective nonpeptide peptidomimetic agonist of the δ-opioid receptor. In a previous report we had described the unique biological characteristics of this ligand and also a need for further structural evaluation. To pursue this, we have introduced a completely different heterocyclic template (2 and 3), which, based on molecular modeling studies, may present the required structural features to properly orient the pharmacophore groups. We also have made more subtle changes to the original piperazine scaffold (5 and 11). The biological activities of these compounds revealed an important participation of the scaffold in the ligand-receptor interaction. To further explore functional diversity on the scaffold, we have maintained the original piperazine ring and introduced four different functionalities at position 2 of the heterocyclic ring (15a-d; a = CH2-O-CH2-Ph; b = Me; c = CH2Ph; d = CH2OH). The biological activities observed for these compounds showed a very interesting trend in terms of the steric effects of the groups introduced at this position. A decrease of almost 2000-fold in affinity and potency at the δ- receptor was observed for 15c compared with 15b. This difference may be explained if we postulate that the bioactive conformation of these peptidomimetics is close to the minimal energy conformations calculated in our study. On the basis of these findings we have realized the importance of this position to further explore and simplify the structure of future generations of peptidomimetic ligands.
- Alfaro-Lopez, Josue,Okayama, Toru,Hosohata, Keiko,Davis, Peg,Porreca, Frank,Yamamura, Henry I.,Hruby, Victor J.
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p. 5359 - 5368
(2007/10/03)
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