2-Pyrrolidinylideneureas, a new class of central nervous system agents

Dicyanotriphenylamine-Based Polyimides as High-Performance Electrodes for Next Generation Organic Lithium-Ion Batteries

Aromatic polyimide (PI) derivatives have recently been investigated as redox-active electrode materials for Li-ion batteries because of their high thermal stability and thermo-oxidative stability complemented by excellent solvent resistance, good electrical and mechanical properties, and chemical resistance. In this work, we report two PI derivatives from a newly synthesized 4,4'-diamino-3″,4″-dicyanotriphenylamine (DiCN-TPA) monomer and two dianhydrides, pyromellitic dianhydride (PMDA) and 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA); designated as TPA-PMPI and TPA-NTCPI, respectively, as electrode materials for Li-ion batteries. Characterizations of the PIs reveal excellent thermal stability and bipolar property. The incorporation of DiCN-TPA into the polymer structure resulted to a disordered chain arrangement, thus giving high glass transition temperatures (T_g). Electrochemical performance tests reveal that TPA-NTCPI cathode delivered a reversible specific capacity of 150 mAh g^-1 at 0.1 A g^-1 and exhibited a stability up to 1000 cycles. On the other hand, TPA-PMPI anode delivered a high specific capacity of up to 1600 mAh g^-1 at 0.1 A g^-1 after 100 cycles. The electrochemical performance of TPA-NTCPI cathode and TPA-PMPI anode are both among the best compared with other reported aromatic PI-based electrodes. The long cycle lifetime and excellent battery performance further suggest that TPA-NTCPI and TPA-PMPI are promising organic electrode materials for next generation Li-ion batteries.

Selenolactams as Synthetic Intermediates for the Synthesis of Polycyclic Amines via Seleno-Claisen Rearrangements

A highly diastereoselective α-allylation of selenolactams with allyl halides is reported. DFT analyses and experimental observations suggested that this reaction proceeds via a Se-allylation of the eneselenolates of the lactams followed by a seleno-Claisen rearrangement. The thus-obtained products could be efficiently transformed into polycyclic amines using a previously developed sequential addition of organometallic reagents and ring-closing metathesis.

Development of Potent and Selective Antagonists for the UTP-Activated P2Y4 Receptor

P2Y₄ is a G_q protein-coupled receptor activated by uridine-5'-triphosphate (UTP), which is widely expressed in the body, e.g., in intestine, heart, and brain. No selective P2Y₄ receptor antagonist has been described so far. Therefore, we developed and optimized P2Y₄ receptor antagonists based on an anthraquinone scaffold. Potency was assessed by a fluorescence-based assay measuring inhibition of UTP-induced intracellular calcium release in 1321N1 astrocytoma cells stably transfected with the human P2Y₄ receptor. The most potent compound of the present series, sodium 1-amino-4-[4-(2,4-dimethylphenylthio)phenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate (PSB-16133, 61) exhibited an IC₅₀ value of 233 nM, selectivity versus other P2Y receptor subtypes, and is thought to act as an allosteric antagonist. A receptor homology model was built and docking studies were performed to analyze ligand-receptor interactions. Compound 64 (PSB-1699, sodium 1-amino-4-[4-(3-pyridin-3-ylmethylthio)phenylamino]-9,10-dioxo-9,10-dihydroanthracene-2-sulfonate) represents the most selective P2Y₄ receptor antagonist known to date. Compounds 61 and 64 are therefore anticipated to become useful tools for studying this scarcely investigated receptor.

Microwave-assisted cyclizations promoted by polyphosphoric acid esters: a general method for 1-aryl-2-iminoazacycloalkanes

The first general procedure for the synthesis of 5 to 7-membered 1-aryl-2-iminoazacycloalkanes is presented, by microwave-assisted ring closure of ω-arylaminonitriles promoted by polyphosphoric acid (PPA) esters. 1-Aryl-2-iminopyrrolidines were easily prepared from the acyclic precursors employing a chloroformic solution of ethyl polyphosphate (PPE). The use of trimethylsilyl polyphosphate (PPSE) in solvent-free conditions allowed for the synthesis of 1-aryl-2-iminopiperidines and hitherto unreported 1-aryl-2-iminoazepanes. The cyclization reaction involves good to high yields and short reaction times, and represents a novel application of PPA esters in heterocyclic synthesis.

Zinc(ii)-mediated generation of 5-amino substituted 2,3-dihydro-1,2,4-oxadiazoles and their further ZnII-catalyzed and O2-involving transformations

Zn^II-activated cyanamides NCNR₂ react with the acyclic N-alkyl ketonitrones Ph₂CN⁺(O⁻)R′ achieving uncomplexed 2,3-dihydro-1,2,4-oxadiazoles.

4-Nitro-phthalo-nitrile

In the title compound, C₈H₃N₃O₂ (systematic name: 4-nitro­benzene-1,2-dicarbo­nitrile), the nitro group is twisted out of the plane of the benzene ring to which it is attached [O—N—C_ring—C_ring torsion angle = 9.80 (13)°]. In the crystal packing, supra­molecular layers with a zigzag topology in the ac plane are sustained by C—H⋯N inter­actions.

4-Nitrophthalamide

In the title compound, C₈H₇N₃O₄ (systematic name: 4-nitro­benzene-1,2-dicarboxamide), each of the substituents is twisted out of the plane of the benzene ring to which it is attached [dihedral angles of 11.36 (2)° for the nitro group, and 60.89 (6) and 34.39 (6)° for the amide groups]. The amide groups are orientated to either side of the least-squares plane through the benzene ring with the amine groups being directed furthest apart. In the crystal, a three-dimensional architecture is established by a network of N—H⋯O hydrogen bonds.

Phenyl ureas of creatinine as mGluR5 antagonists. A structure–activity relationship study of fenobam analogues

Fenobam (1) was developed by McNeil Laboratories as an anxiolytic agent with an unknown molecular target in the late 1970s. In a recent publication, it was revealed that fenobam is a non-competitive mGluR5 antagonist. Herein, we present the structure-activity relationship of fenobam and its analogues and similarities between the SAR of mGluR5 antagonism and the SAR of CNS properties originally reported by McNeil are discussed.

New prodrugs derived from 6-aminodopamine and 4-aminophenol as candidates for melanocyte-directed enzyme prodrug therapy (MDEPT)

Two novel tyrosinase mediated drug delivery pathways have been investigated for the selective delivery of cytotoxic units to melanocytes from urea and thiourea prodrugs. The synthesis of these prodrugs is reported, as well as oximetry data that illustrate that the targets are substrates for tyrosinase. The stability of each of the prodrugs in (i) phosphate buffer and (ii) bovine serum is discussed, and the urea prodrugs are identified as lead candidates for further studies. Finally, HPLC studies and preliminary cytotoxicity studies in a melanotic and an amelanotic cell line, that illustrate the feasibility of the approach, are presented.

1-Methyl-3-pyrrolines and 2-methylisoindolines: new classes of cyclic tertiary amine monoamine oxidase B substrates

Both 1-methyl-3-pyrrolines and 2-methylisoindolines are substrates for MAO-B with Vmax/Km values ranging from 200 to 2000 min-1 mM-1 at 37 degrees C. These compounds represent new classes of cyclic tertiary amine substrates for this flavoenzyme. The only other known cyclic amines that are MAO-B substrates are 1,4-disubstituted 1,2,3,6-tetrahydropyridinyl derivatives. The presence of an allylic (benzylic) amino functionality in all of these compounds may be linked to their substrate properties since related piperidinyl and pyrrolidinyl analogs are stable in the presence of MAO-B. This paper discusses energetic and geometric features of these compounds in relationship to their substrate properties and in anticipation of their utility to probe the active site of this flavoenzyme.

2-Iminopiperidine and other 2-iminoazaheterocycles as potent inhibitors of human nitric oxide synthase isoforms

A series of 2-iminoazaheterocycles have been prepared and shown to be potent inhibitors of human nitric oxide synthase (NOS) isoforms. This series includes cyclic amidines ranging from five- to nine-membered rings, of which 2-iminopiperidine and 2-iminohomopiperidine were the most potent inhibitors, with IC50 values of 1.0 and 2.0 microM, respectively, for human inducible nitric oxide synthase. This series of cyclic inhibitors was further expanded to include analogs with heteroatoms in the 3-position of the six-membered ring. This modification was tolerated for sulfur and oxygen, but nitrogen reduced the inhibitory potency. The oral administration of 2-iminopiperidine in lipopolysaccharide (LPS)-treated rats inhibited the LPS-induced increase in plasma nitrite/nitrate levels in a dose-dependent manner, demonstrating its ability to inhibit inducible NOS activity in vivo. These cyclic amidines represent a new class of potent NOS inhibitors and the foundation for potential therapeutic agents.

Metabolism of xilobam in laboratory animals and man

1. Biotransformation and excretion of xilobam (Xm) were studied after single oral doses of Xm-14C in mouse, rat, dog and man. 2. Following oral administration of Xm-14C, recoveries of total 14C (0-24 h) in urine were > or = 78% of the dose in all species. 3. Xm and a total of 11 metabolites have been isolated and identified, which accounted for 30, 65, 21 and 49% of the total 14C in the urine samples from mouse, rat, dog and man, respectively. 4. Xm was sequentially oxidized at the pyrrolidine ring to form 5'-OH Xm and 5'-oxo Xm. Both metabolites were isolated from human plasma accounting for 61% of the radioactivity in the sample. 5'-OH Xm was also identified as a major in vitro metabolite in the 9000g supernatant from a rat liver homogenate preparation. 5. 5'-OH Xm was isolated from the urine of all species except rats. However, oxidation products of 5'-oxo Xm were also present. Oxidation at the phenyl (ph) ring and at the phCH3 group produced the corresponding 4-OHph and phCH2OH metabolites. Subsequent water addition at the 2-position of the pyrrolidine ring followed by cleavage and/or cyclization of the above metabolites resulted in six additional urinary metabolites.

In vitro inhibition of animal and higher plants 2,3-oxidosqualene-sterol cyclases by 2-aza-2,3-dihydrosqualene and derivatives, and by other ammonium-containing molecules

2-Aza-2,3-dihydrosqualene and related molecules, a series of new compounds designed as analogues of the transient carbocationic high energy intermediate, occurring in the oxirane ring opening during the cyclization of 2,3-oxidosqualene, were tested in vitro as inhibitors of the microsomal 2,3-oxidosqualene cyclase of animals (rat liver) and of higher plants (maize, pea). These molecules proved to be good and specific inhibitors for the cyclases of both phyla. The inhibition is due to positively charged species and is sensitive to the steric hindrance around the nitrogen-atom. 4,4,10 beta-Trimethyl-trans-decal-3 beta-ol and 4,10 beta-dimethyl-trans-decal-3 beta-ol, which have previously been described (J.A. Nelson et al., J. Am. chem. Soc. 100, 4900 (1978] as inhibitors of the 2,3-oxidosqualene cyclase of chinese hamster ovary cells, were found to be non-competitive inhibitors of the rat liver microsomal enzyme and presented no activity towards the higher plants cyclases. Aza derivatives of these decalines (A. Rahier et al., Phytochemistry, in press), which were aimed to mimic the C-8 carbocationic intermediate occurring during later steps of the 2,3-oxidosqualene cyclization did not inhibit the cyclases. This result underlines the theoretical limitations of the high energy analogues concept in designing enzyme inhibitors. Amongst other molecules tested, 2,3-epiminosqualene was found to be a reversible, non-competitive inhibitor of the cyclases; similarly U18666A was a very potent inhibitor of the microsomal cyclases. In contrast AMO 1618, a known anticholesterolemic agent reported previously to act at the level of the 2,3-oxidosqualene cyclization step, was not found per se to act on the cyclases.

Xilobam: analysis, determination of decomposition products, and assessment of stability

A stability-indicating UV assay was developed for xilobam, a member of a new class of CNS agents. The method was specific, precise, and accurate. TLC and high-pressure liquid chromatography were used to support method specificity. Xilobam is sensitive to heat, moisture, and basic conditions. The degradation products were identified as N-methylpyrrolidone, 2,6-dimethylaniline, and N,N'-bis(2,6-dimethyl-phenyl)urea. At high temperatures, the incorporation of molecular sieves into glass bottles of xilobam tablets was effective in preventing decomposition caused by moisture or volatile decomposition products.