Showing papers on "Piperidine published in 2021"

Poly(arylene piperidine) Anion Exchange Membranes with Tunable N-Alicyclic Quaternary Ammonium Side Chains

Abstract: To develop anion exchange membranes (AEMs) that combine high chemical stability and hydroxide conductivity, we have designed and prepared poly(arylene piperidine)s carrying tunable mono- or dicationic side chains. Poly(biphenyl piperidine) and poly(biphenyl N-methylpiperidine), respectively, were first synthesized by superacid-catalyzed polyhydroxylalkylations. Subsequently, the piperidine rings of these polymers were reacted with bromoalkylated N,N-dimethylpiperidinium (DMP) and 6-azonia spiro[5.5]undecane (ASU) cations, respectively. This gave two series of AEMs in which the polymer backbone contained tertiary and quaternary piperidine rings, respectively, resulting in mono- and dicationic side chains in series 1 and 2, respectively. In series 1, both the piperidine rings in the backbone and the pendant cations in the side chains showed excellent alkaline stability, resulting in AEMs, which retained more than 92% of the cations after storage in 2 M NaOH at 90 °C during 30 days. In addition, these AEMs reached a hydroxide conductivity up to 131 mS cm–1 at 80 °C. Benefiting from a high local ionic concentration through the dicationic configuration, the AEMs in series 2 reached a higher conductivity, almost 170 mS cm–1 at 80 °C at moderate water uptake and swelling. Still, these AEMs were more vulnerable to hydroxide attack than the ones in series 1 because of the quaternary piperidinium groups placed in the polymer backbone. In conclusion, the AEMs in series 1 can be employed in electrochemical devices that operate under harsh alkaline conditions, while those in series 2 should be preserved for less aggressive alkaline conditions. (Less)

Catalytic Hydrodenitrogenation of Pyridine under Hydrothermal Conditions: A Comprehensive Study

Abstract: This article focuses on the kinetic modeling and catalytic performance of hydrodenitrogenation of pyridine under hydrothermal conditions. Piperidine derivatives are the major nitrogen-containing in...

Catalytic Consequences of Supported Pd Catalysts on Dehydrogenative H2 Evolution from 2-[(n-Methylcyclohexyl)methyl]piperidine as the Liquid Organic Hydrogen Carrier

Abstract: Herein, nanoporous Al2O3, CeO2, TiO2, ZrO2, and SnO2 were used as the supports for Pd nanoparticles, and effects of surface characteristics on catalytic performances for dehydrogenation of 2-[(n-me...

Identification and characterization of piperine synthase from black pepper, Piper nigrum L.

Abstract: Black pepper (Piper nigrum L.) is the world’s most popular spice and is also used as an ingredient in traditional medicine. Its pungent perception is due to the interaction of its major compound, piperine (1-piperoyl-piperidine) with the human TRPV-1 or vanilloid receptor. We now identify the hitherto concealed enzymatic formation of piperine from piperoyl coenzyme A and piperidine based on a differential RNA-Seq approach from developing black pepper fruits. This enzyme is described as piperine synthase (piperoyl-CoA:piperidine piperoyl transferase) and is a member of the BAHD-type of acyltransferases encoded by a gene that is preferentially expressed in immature fruits. A second BAHD-type enzyme, also highly expressed in immature black pepper fruits, has a rather promiscuous substrate specificity, combining diverse CoA-esters with aliphatic and aromatic amines with similar efficiencies, and was termed piperamide synthase. Recombinant piperine and piperamide synthases are members of a small gene family in black pepper. They can be used to facilitate the microbial production of a broad range of medicinally relevant aliphatic and aromatic piperamides based on a wide array of CoA-donors and amine-derived acceptors, offering widespread applications. Schnabel et al. identify and characterize piperine synthase in developing black pepper fruits which catalyses the formation of piperine from piperoyl coenzyme A and piperidine. A member of BAHD-type acyltransferases, this enzyme can be useful for bio-production of a broad range of medicinally relevant piperamides.

Structure-Activity Relationship of Heterocyclic P2Y14 Receptor Antagonists: Removal of the Zwitterionic Character with Piperidine Bioisosteres.

Abstract: A known zwitterionic, heterocyclic P2Y14R antagonist 3a was substituted with diverse groups on the central phenyl and terminal piperidine moieties, following a computational selection process. The most potent analogues contained an uncharged piperidine bioisostere, prescreened in silico, while an aza-scan (central phenyl ring) reduced P2Y14R affinity. Piperidine amide 11, 3-aminopropynyl 19, and 5-(hydroxymethyl)isoxazol-3-yl) 29 congeners in the triazole series maintained moderate receptor affinity. Adaption of 5-(hydroxymethyl)isoxazol-3-yl gave the most potent naphthalene-containing (32; MRS4654; IC50, 15 nM) and less active phenylamide-containing (33) scaffolds. Thus, a zwitterion was nonessential for receptor binding, and molecular docking and dynamics probed the hydroxymethylisoxazole interaction with extracellular loops. Also, amidomethyl ester prodrugs were explored to reversibly block the conserved carboxylate group to provide neutral analogues, which were cleavable by liver esterase, and in vivo efficacy demonstrated. We have, in stages, converted zwitterionic antagonists into neutral molecules designed to produce potent P2Y14R antagonists for in vivo application.

General Light-Mediated, Highly Diastereoselective Piperidine Epimerization: From Most Accessible to Most Stable Stereoisomer.

Abstract: We report a combined photocatalytic and hydrogen atom transfer (HAT) approach for the light-mediated epimerization of readily accessible piperidines to provide the more stable diastereomer with hig...

Development of Anticancer Activity of the Pt(II) Complex with N-Heterocyclic Amine: Its In Vitro Pharmacokinetics with Thiol and Thio-Ethers, DNA and BSA Binding, and Cell Cycle Arrest

Abstract: A dichloro Pt(II) complex with N-heterocyclic amine cis-Pt(PIEAM)Cl2, C-1 (where PIEAM = 1-(2-aminoethyl)piperidine) was synthesized and hydrolyzed to the corresponding [Pt(PIEAM)(OH2)2]2+ C-2 to e...

Piperidine-Mediated [3 + 3] Cyclization of 2-Amino-4H-chromen-4-ones and 2-Benzylidenemalononitriles: To Access 2-Aminochromeno[2,3-b]pyridine Derivatives.

Abstract: Piperidine-mediated [3 + 3] cyclization of 2-amino-4H-chromen-4-ones and substituted 2-benzylidenemalononitriles was developed for the synthesis of 2-amino-4-aryl-5H-chromeno[2,3-b]pyridin-5-one derivatives. This novel transformation provides a highly efficient and facile route to functionalized 5H-chromeno[2,3-b]pyridines from readily available substrates under mild reaction conditions.

Phosphorus-nitrogen compounds: part 53-synthesis, characterization, cytotoxic and antimicrobial activity, DNA interaction and molecular docking studies of new mono- and dispirocyclotriphosphazenes with pendant arm(s).

Abstract: Mono-/dispirocyclotriphosphazenes with pendant arm(s) are robust, but they are less investigated inorganic ring systems. In this study, a series of mono (3 and 4)- and dispirocyclotriphosphazenes with 4-chloro-benzyl pendant arm(s) (13-16) was obtained from the Cl exchange reactions of hexachlorocyclotriphosphazene with sodium (N-benzyl)aminopropanoxides (1 and 2). When compound (3) reacted with excess pyrrolidine, morpholine, tetra-1,4-dioxa-8-azaspiro[4,5]decane (DASD) and piperidine, the fully substituted monospirocyclotriphosphazenes (7, 9, 10 and 12) occurred. But, the reactions of 4 with excess piperidine and morpholine produced the gem-piperidino (5)- and morpholino (6)-substituted monospirocyclotriphosphazenes, whereas the reactions of 4 with excess pyrrolidine and DASD gave the fully substituted monospirocyclotriphosphazenes (8) and (11). However, it should be indicated that these derivatives were obtained to be used for the investigation of their spectral, stereogenic and biological properties. The structures of 5, 7 and 14 were determined crystallographically. X-ray data of 5 and 14 displayed that both of compounds were chiral in solid state, and their absolute configurations were assigned as R and RR. Additionally, the antimicrobial activities of phosphazenes were investigated. Minimum inhibitory concentrations, minimal bacterial concentrations and minimum fungicidal concentrations of phosphazenes were determined. The interactions of phosphazenes with plasmid DNA were evaluated by agarose gel electrophoresis. The cytotoxic activities of compounds were studied against L929 fibroblast and DLD-1 colon cancer cells. In addition, density functional theory calculations of 5, 7 and 14 were reported, and their molecular docking studies with DNA, E. coli DNA gyrase and topoisomerase IV were presented.

Total Synthesis of (-)-Lepadin F based on a Stereoselective Diels-Alder Reaction Controlled by a Ketolactone-type Dienophile.

Abstract: An efficient approach to the type III lepadin alkaloids (lepadins F and G) has been developed through a key Diels-Alder reaction, in which a novel ketolactone-type dienophile with chiral diol unit is employed to generate the desirable all-cis-trisubstituted cyclohexene with excellent regio- and stereoselectivity control. The subsequent selective sulfonylation of the diol unit followed by SN 2 cyclization under hydrogenation conditions could construct the substituted piperidine ring. By using this approach, (-)-lepadin F is synthesized from ethyl l-lactate for the first time.

Synthesis of biological based hennotannic acid-based salts over porous bismuth coordination polymer with phosphorous acid tags

Abstract: In this paper, a novel porous polymer capable of coordinating to bismuth (PCPs-Bi) was synthesized. The Bi-PCPs was then reacted with phosphorous acid to produce a novel polymer PCPs(Bi)N(CH2PO3H2)2 which is shown to act as an efficient and recyclable catalyst. The mentioned catalyst was applied for the efficient synthesis of new mono and bis naphthoquinone-based salts of piperidine and/or piperazine via the reaction of hennotannic acid with various aldehydes, piperidine and/or piperazine, respectively. The structure of the resulting mono and bis substituted piperazine or piperidine-based naphthoquinone salts was thoroughly characterized spectroscopically. The electrochemical behavior of the products was also investigated. The presented protocol has the advantages of excellent yields (82–95%), short reaction times (4–30 min) and simple work-up.

Crystallographic and Theoretical Exploration of Weak Hydrogen Bonds in Arylmethyl N'-(adamantan-1-yl)piperidine-1-carbothioimidates and Molecular Docking Analysis.

Abstract: Crystal structures of two potential chemotherapeutic agents, namely 4-nitrobenzyl N'-(adamantan-1-yl)piperidine-1-carbothioimidate 1 and 4-bromobenzyl N'-(adamantan-1-yl)piperidine-1-carbothioimidate 2, have been analyzed in detail. X-ray analysis reveals that the molecular conformations of these compounds are strikingly different. These two structures are compared with two of their closely related structures. In the related structures, morpholine replaces piperidine. Based on the Hirshfeld surface analysis and two-dimensional (2D) fingerprint plots, we describe the effects of piperidine/morpholine and Br/NO2 groups on the intermolecular interactions. An analysis of the CLP-PIXEL energy provides insight into the energetics of the dimers observed in the title compounds and their related structures. Compound 1 stabilizes with bifurcated C-H···S, C-H···O, and O(lp)···C(π) interactions, whereas compound 2 stabilizes with C-H···N, C-H···Br, and C-H···C interactions. The energy frameworks for the crystal structures of the title compounds reveal differences. The atoms-in-molecules (AIM) analysis was performed to confirm the intermolecular interactions found in the crystal structures of 1 and 2. Additionally, docking analysis suggests that the title compounds bind at the active site of human sphingosine kinase 1, a well-known cancer target.

Diversity-Oriented Stereocontrolled Synthesis of Some Piperidine- and Azepane-Based Fluorine-Containing β-Amino Acid Derivatives

Abstract: Structural diversity-oriented synthesis of some azaheterocyclic β-amino acid derivatives has been accomplished by selective functionalization of readily available cyclodienes. The stereocontrolled synthetic concept was based on the oxidative ring cleavage of unsaturated cyclic β-amino acids derived from cycloalkadiene, followed by ring closing with double reductive amination, which furnished some conformationally restricted β-amino acid derivatives with a piperidine or azepane core.

Enantioselective Total Synthesis of (+)-Alstilobanine C, (+)-Undulifoline, and (−)-Alpneumine H

Abstract: We report herein the enantioselective total synthesis of three monoterpene indole alkaloids, namely, (+)-alstilobanine C, (+)-undulifoline, and (-)-alpneumine H. The key features of our synthesis include: a) introduction of chirality via enantioselective deprotonation of a prochiral 4-substituted cyclohexanone; b) use of methoxymethyl (MOM) ether as both a hydroxyl protective group and a latent oxonium species for the formation of bridged oxepane and c) domino double reductive cyclization to build both the indole and the piperidine ring at the end of the synthesis. The synthesis confirmed the absolute configuration of these natural products assigned based on the biogenetic hypothesis.

Covalent cross-linked anion exchange membrane based on poly(biphenyl piperidine) and poly(styrene-b-(ethylene-co-butylene)-b-styrene): preparation and properties

Abstract: Poly(biphenyl piperidine) and polystyrene‑b‑poly(ethylene-co-butylene)‑b‑polystyrene were cross-linked to form a polymer backbone, piperidine as the ionic conducting group to improve the chemical s...

Multi-Stimuli Responsive Luminescent β-Diketones and Difluoroboron Complexes with Heterocyclic Substituents

Abstract: Emissive β-diketones (bdks) and difluoroboron complexes (BF2bdks) exhibit multi-stimuli responsive luminescence, including solvatochromism, viscochromism, aggregation induced emission, thermal and mechanochromic luminescence, halochromism and pH sensing. In this study, a series of six-membered heterocycle-substituted (piperidine, morpholine, 1-methyl piperazine) bdk ligands and boron complexes were synthesized, and their luminescent properties were investigated. All the compounds exhibited red-shifted emission in more polar solvents due to intramolecular charge transfer as well as higher emission intensity in more viscous environments. In response to solubility changes in water/tetrahydrofuran mixtures, while the piperazine bdk ligand showed aggregation caused quenching, the piperidine and morpholine bdks displayed enhanced emission upon aggregation. In the solid state, all ligands exhibited mechanochromism. More dramatic halochromism was observed for the piperidine boron dye spin cast film. In solution, for the boron dyes under varying pH values (1-13), different protonated and deprotonated forms were analyzed according to the measured emission spectra. Graphical abstract Multi-stimuli responsive luminescent properties were investigated for the six-membered heterocycle-substituted β-diketone ligands and difluoroboron complexes.