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At least 19 recordsLinked to original sources
PubMed1996

Imide Transfer Properties and Reactions of the Magnesium Imide ((THF)MgNPh)(6): A Versatile Synthetic Reagent.

Imide transfer properties of ((THF)MgNPh)(6) (1) and the synthesis of the related species {(THF)MgN(1-naphthyl)}(6).2.25THF (2), via the reaction of dibutylmagnesium with H(2)N(1-naphthyl), in a THF/heptane mixture are described. Treatment of 1 with Ph(2)CO, 4-Me(2)NC(6)H(4)NO, t-BuNBr(2) (3), PCl(3), or MesPCl(2) (Mes = 2,4,6-Me(3)C(6)H(2)-) leads to the isolation of Ph(2)CNPh (4), 4-Me(2)NC(6)H(4)NNPh (5), t-BuNNPh (6), (PhNPCl)(2) (7), or (MesPNPh)(2) (8) in moderate yield. Reaction between 1 and GeCl(2).dioxane, SnCl(2), or PbCl(2) affords the M(4)N(4) (M = Ge, Sn, Pb) cubane imide derivative (GeNPh)(4) (9), [(SnNPh)(4).{MgCl(2)(THF)(4)}](infinity) (10), (SnNPh)(4).0.5PhMe (11), or (PbNPh)(4).0.5PhMe (12). Interaction of 1 with Ph(3)PO, (Me(2)N)(3)PO, or Ph(2)SO furnishes the complex (Ph(3)POMgNPh)(6) (13), {(Me(2)N)(3)POMgNPh}(6).2PhMe (14), or (Ph(2)SOMgNPh)(6) (15). The addition of 3 equiv of MgBr(2) to 1 gives 1.5 equiv of ((THF)Mg)(6)(NPh)(4)Br(4) (16) in quantitative yield, whereas treatment of 16 with 4 equiv of 1,4-dioxane is an alternative synthetic route to 1. Compounds 2, 3, 9, 10, and 14 were characterized by X-ray crystallography. The reactions demonstrate that 1 is a versatile and useful reagent for the synthesis of a variety of main group imides. Crystal data at 130 K with Mo Kalpha (lambda = 0.710 73 Å) radiation for 3 or Cu Kalpha (lambda = 1.541 78 Å) radiation for 2, 9, 10, and 14: 2, C(93)H(108)Mg(6)N(6)O(7.25), a = 28.101(7) Å, b = 35.851(7) Å, c = 36.816(7) Å, Z = 2, space group Fddd, R = 0.068 for 3500 (I > 2sigma(I)) data; 3, C(4)H(9)Br(2)N, a = 6.682(2) Å, b = 10.834(3) Å, c = 11.080(3) Å, alpha = 66.25(2) degrees, beta = 89.88(2) degrees, gamma = 82.53(2) degrees, Z = 4, space group P&onemacr;, R = 0.038 for 2043 (I > 2sigma(I)) data; 9, C(24)H(20)Ge(4)N(4), a = 10.749(2) Å, b = 12.358(3) Å, c = 35.818(7) Å, Z = 8, space group Pbca, R = 0.040 for 2981 (I > 2sigma(I)) data; 10, C(40)H(52)Cl(2)MgN(4)O(4)Sn(4), a = 12.770(3) Å, b = 13.554(3) Å, c = 25.839(5) Å, Z = 4, space group P2(1)2(1)2(1), R = 0.040 for (I > 2sigma(I)) data; 14, C(86)H(154)Mg(6)N(4)O(6)P(6), a = 22.478(4) Å, b = 16.339(3) Å, c = 29.387(6) Å, Z = 4, space group Pbcn, R = 0.081 for 4696 (I >2sigma(I)) data.

Journal Article↗
PubMed2006

Thiourea-catalyzed asymmetric michael addition of activated methylene compounds to alpha,beta-unsaturated imides: dual activation of imide by intra- and intermolecular hydrogen bonding.

A thiourea-catalyzed asymmetric Michael addition of activated methylene compounds to alpha,beta-unsaturated imides derived from 2-pyrrolidinone and 2-methoxybenzamide has been developed. In the case of 2-pyrrolidinone derivatives, the reaction with malononitrile proceeded in toluene with high enantioselectivity, providing the Michael adducts in good yields. However, the nucleophiles that could be used for this reaction were limited to malononitrile due to poor reactivity of the substrate. Further examination revealed that N-alkenoyl-2-methoxybenzamide was the best substrate among the corresponding benzamide derivatives bearing different substituents on the aromatic ring. Indeed, several activated methylene compounds such as malononitrile, methyl alpha-cyanoacetate, and nitromethane could be employed as a nucleophile to give the Michael adducts in good to excellent yields with up to 93% ee. The results of spectroscopic experiments clarified that this enhanced reactivity can be attributed to the intramolecular hydrogen-bonding interaction between the N-H of the imide and the methoxy group of the benzamide moiety. Thus, the key to the success of the catalytic enantioselective Michael addition is dual activation of the substrate by both intramolecular hydrogen bonding in the imide and intermolecular hydrogen bonding with thiourea 1a, as well as the activation of a nucleophile by the tertiary amine of the bifunctional thiourea.

Journal Article↗
PubMed1991

Lithium-selective permeation through lipid bilayer membranes mediated by a di-imide ionophore with nonsymmetrical imide substituents (ETH1810).

The neutral, noncyclic Li(+)-selective ionophore ETH1810, which is a di-imide, differs structurally from previous similar ionophores by removal of the intramolecular symmetry of the N-imide substituents. Properties of this ionophore, as a potential carrier of lithium, were probed through studies of ionophore-induced changes in electrical properties of lipid bilayer membranes. ETH1810 was found capable of transporting lithium and other monovalent cations, across lipid bilayer membranes, forming 2:1 ionophore:ion membrane-permeating species. It was found to be 10-fold more potent than ETH1644, which was the previous best ionophore of this type. The selectivity sequence among alkali cations was found to be: Li+ (1) greater than Na+ (0.009) greater than K+ (0.004) greater than Cs+ (0.0035). Among the physiological alkali cations, it constitutes a 40 (vs. Na+) to 160% (vs. K+) improvement over ETH1644. ETH1810 was also found to be capable of acting as a carrier of biogenic amines and related molecules, with the following selectivity sequence:tryptamine (20) greater than phenylethylamine (7.8) greater than tyramine (4.3) greater than serotonin (2.5) greater than Li+ (1) greater than NH+4 (0.013) greater than dopamine (0.012). It was found that protons, at physiological concentrations, do not interfere with the lithium transport mediated by ETH1810. The relationship between the improvements in ionic selectivity and potency vs. the differences in structural features is discussed.

Biogenic Amines↗
PubMed2001

New dinuclear catalysts Rh(2)(N-O)(2)[(C6H4)P(C6H5)2]2 with imidate ligands: synthesis and isomerization from head-to-tail to head-to-head configuration of the imidate ligands.

Two new dirhodium(II) catalysts of general formula Rh(2)(N-O)(2)[(C(6)H(4))P(C(6)H(5))(2)](2) (N-O = C(4)H(4)NO(2)) are prepared, starting from Rh(2)(O(2)CCH(3))(2)(PC)(2)L(2) [PC = (C(6)H(4))P(C(6)H(5))(2) (head-to-tail arrangement); L = HO(2)CCH(3)]. The thermal reaction of Rh(2)(O(2)CCH(3))(2)(PC)(2).L(2) with the neutral succinimide stereoselectively gives one compound that according to the X-ray structure determination has the formula Rh(2)(C(4)H(4)NO(2))(2)[(C(6)H(4))P(C(6)H(5))(2)](2) (1). It corresponds to the polar isomer with two bridging imidate ligands in a head-to-head configuration. However, stepwise reaction of Rh(2)(O(2)CCH(3))(2)(PC)(2).L(2) with (CH(3))(3)SiCl and potassium succinimidate yields a mixture of 1 and one of the two possible isomers (structure B) with a head-to-tail configuration of the imidate ligands, Rh(2)(C(4)H(4)NO(2))(2)[(C(6)H(4))P(C(6)H(5))(2)](2) (2), also characterized by X-ray methods. In solution, compound 2 undergoes slow isomerization to 1; the rate of this process is enhanced by the presence of acetonitrile. Compounds 1 and 2 are obtained as pure enantiomers starting from (M)- and (P)-Rh(2)(O(2)CCH(3))(2)(PC)(2).L(2) rather than from the racemic mixture. Their enantioselectivities in cyclopropanation of 1-diazo-5-penten-2-one are similar to those reported for the dirhodium amidate catalysts.

Journal Article↗
PubMed2005

In situ infrared spectroscopy study on imidization reaction and imidization-induced refractive index and thickness variations in microscale thin films of a poly(amic ester).

Poly(amic ester) (PAE) is a soluble precursor of polyimide that has attracted interest from both the microelectronic and the flat-panel display industries because of its several important advantages, including excellent solubility, high hydrolytic stability, and solvent-free film formation, over the polyimide precursor, poly(amic acid), for which monomer-polymer equilibration always occurs in solution due to its carboxylic acid groups. In this study, poly(3,4'-oxydiphenylene pyromellitamic diethyl ester) (PMDA-3,4'-ODA PAE) was chosen as a PAE precursor, and its thermal imidization behavior in microscale thin films was investigated quantitatively for the first time using time-resolved infrared (IR) spectroscopy. In addition, the variations of the film refractive index and thickness with temperature and time were determined in detail from the time-resolved IR spectra and are fully interpreted in this paper by considering the imidization kinetics of the precursor.

Journal Article↗
PubMed2002

Rebek imides and their adenine complexes: preferences for Hoogsteen binding in the solid state and in solution.

Rebek imides (3), formed from Kemp's triacid, were developed in the mid-1980's as model receptors for adenine derivatives. We report here the first account of their hydrogen-bonding preferences upon binding 9-ethyladenine (1a) in the solid state. Structural analysis begins with simple imides 3a-e that form discrete dimers, while bis-imide 4 forms ribbon-like structures in the crystalline phase. The hydrogen-bonding interface within each of the representative assemblies features short intermolecular N(3)imide...O(8*)imide* distances (ca. 2.95 A), indicative of two-point hydrogen bonding. Imides 3f-h could be co-crystallized with 1a; single-crystal X-ray analysis of the resulting complexes reveals hydrogen-bonding geometries nearly identical to those observed in nucleobase complexes of adenine and pyrimidine derivatives. Imides 3f and 3g form 2:1 ternary assemblies with 1a; the complex of the former, (3f)2 x 1a, displays both Watson-Crick- and Hoogsteen-type hydrogen bonding, whereas the complex of the latter, (3g)2 x 1a, shows the Hoogsteen motif and imide hydrogen bonding to N(3) of the purine base (N(3)adenine...N(3'')imide = 3.07(1) A). Imide 3h forms a 1:1 complex with 1a (3h x 1a x CHCl3) and displays Hoogsteen binding exclusively. All of the 3 x 1a assemblies show C(adenine)...O(imide) distances (3.38-3.75 A) that are consistent with C-H...O hydrogen bonding. Base-pairing preferences for the Rebek imides are further explored in solution by 1H NMR one-dimensional NOE experiments and by computational means; in all cases the Hoogsteen motif is modestly favored relative to its Watson-Crick counterpart.

Adenine↗
PubMed1999

Functional and electrophysiological effects of a novel imidazoline-based K(ATP) channel blocker, IMID-4F.

1. The functional and electrophysiological effects of IMID-4F (2-[N-(2, 6-dichlorophenyl)-N-(4-flurorobenzyl)amino]imidazoline), a fluoro-benzyl derivative of clonidine, on vascular K(ATP) channels were investigated. In pig coronary artery, IMID-4F inhibited the vasorelaxation response to the K(ATP) channel opener levcromakalim with a pK(B) value of approximately 7.1. IMID-4F (30 microM) did not affect the vasorelaxation response to sodium nitroprusside (SNP). 2. In rat mesenteric artery smooth muscle cells IMID-4F (1 - 10 microM) caused a concentration-dependent depolarization of membrane potential. IMID-4F (10 microM) abolished the hyperpolarizing effects of levcromakalim (10 microM). 3. In patch clamp experiments using rat mesenteric artery smooth muscle cells, K(ATP) channel currents induced by levcromakalim (10 microM) were inhibited by IMID-4F (0.3 - 3 microM) in a concentration-dependent manner. The calculated IC(50) for IMID-4F inhibiting K(ATP) channel current was approximately 0.8 microM. 4. Radioligand binding studies using bovine aortic smooth muscle cell membranes showed that IMID-4F (30 microM) did not displace binding to the K(ATP) channel opener [(3)H]-P1075. However, both levcromakalim (10 microM) and glibenclamide (10 microM) caused significant displacement of [(3)H]-P1075. 5. These studies show that the imidazoline compound IMID-4F is one of the most potent antagonists of arterial K(ATP) channels identified. Vasorelaxation, hyperpolarization and K(+) currents through K(ATP) channels were all inhibited by IMID-4F at micromolar concentrations. Radioligand binding studies indicate that IMID-4F does not bind to the same site as levcromakalim or as glibenclamide. Considering other evidence, it is likely that IMID-4F acts by interacting directly with the pore of the K(IR) channel, rather than through the sulphonylurea subunit of the K(ATP) channel complex.

Aniline Compounds↗
PubMed2005

IMiDs: a novel class of immunomodulators.

IMiDs are structural and functional analogues of thalidomide that represent a promising new class of immunomodulators for treatment of a variety of inflammatory, autoimmune, and neoplastic diseases. The discovery of the antiangiogenic and T-cell co-stimulatory functions of IMiD compounds has led to the investigation of these agents for treatment of hematologic neoplasms such as multiple myeloma and myelodysplastic syndromes, as well as certain solid tumors. The second-generation IMiDs, such as lenalidomide and CC-4047, exhibited a greatly enhanced potency for immunomodulation and antiangiogenesis in nonclinical studies when compared with the parent compound, thalidomide. In clinical studies, the IMiDs appear to have reduced sedative and neurotoxicity effects, which are often associated with long-term thalidomide dosing. The precise mechanism of action of IMiDs in the treatment of specific diseases is not entirely clear and may differ for various diseases depending on their underlying pathobiologies. Although IMiDs have similar effects on inflammatory cytokine secretion, T-cell modulation, angiogenesis, and expression of adhesion molecules, each IMiD has a unique potency profile for these activities, which may ultimately indicate selective applicability of specific IMiDs for distinct diseases and conditions. Clinical trials of lenalidomide, the primary second-generation IMiD, have shown clinical benefits in both myelodysplastic syndrome and multiple myeloma and a better safety profile than that of thalidomide, with no evidence of teratogenicity. It is anticipated that lenalidomide and other IMiD compounds will become important alternatives to thalidomide because of their more potent anti-inflammatory and anticancer properties, as well as their improved side-effect profiles.

Angiogenesis Inhibitors↗
PubMed1990

Formation of cyclic imide-like structures upon the treatment of calmodulin and a calmodulin peptide with heat.

Protein cyclic imide is the putative intermediate in the formation of sites of carboxyl-methylation in eukaryotic proteins. Conditions known to induce the formation of a cyclic imide in model peptides have been applied to a protein, calmodulin. Heating of calmodulin in the dry state at 100 degrees C for 24 h after lyophilization from a pH 2.0 or pH 6.0 solution produces derivatives with altered chromatographic properties in anion-exchange HPLC. At pH 6.0, complete activity of calmodulin was retained. Analysis with Fourier transform infrared (FTIR)-photoacoustic spectroscopy demonstrated the presence of a new structure in the calmodulin molecule consistent with modification of carboxylic acid groups. The conversion of calmodulin is dependent upon the absence of Ca2+ (the presence of 1 mM ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid). A peptide analogous to the calcium binding regions of calmodulin, Asp-Lys-Asp-Gly-Asn-Gly-Thr-Ile-Thr-Thr-Lys-Glu, is also converted, upon heating, to chromatographically different forms in reversed-phase chromatography. This process is also dependent upon the absence of calcium. Sequence analysis of the peptide derivatives reveals a second amino terminus, implicating peptide bond hydrolysis in the product. A dipeptide, Asp-Gly, known to form a cyclic imide structure under similar conditions is also hydrolyzed during sequence analysis consistent with cleavage occurring at the position of the cyclic imide structure. Asp3 is suggested to be the site of cyclic imide formation in the calmodulin peptide. The presence of a cyclic imide structure is also confirmed by the application of FTIR-photoacoustic spectroscopy. These data suggest that cyclic imide formation in calmodulin has been induced, possibly at one, or more, of the calcium binding loops of the protein. These modification reactions may provide a basis for future investigations of cyclic imide formation in proteins.

Amino Acid Sequence↗
PubMed1998

Chemical changes during in vivo degradation of poly(anhydride-imide) matrices.

The in vivo degradation characteristics of a novel class of biodegradable polymers, poly(anhydride-imides), were investigated. The poly(anhydride-imides) examined were poly[trimellitylimidoglycine-co-1,6-bis(p-carboxyphenoxy)hex ane] (TMA-gly:CPH) in 10:90, 30:70 and 50:50 molar ratios and poly[pyromellitylimidoalanine-co-1,6-bis(p-carboxyphenoxy)he xane] (PMA-ala:CPH) in 10:90 and 30:70 molar ratios. The polymer matrices were compression-molded into circular discs, then implanted in rat subcutaneous tissues for nearly two months. At defined time intervals, the animals were sacrificed and explants analyzed. Proton NMR spectroscopic analysis revealed a complete absence of imide monomer units in PMA-ala: CPH compositions after 28 d and complete removal of imide units at 56 d from TMA-gly matrices. Gross observation of the implants closely correlated to the imide content: with decreasing imide content, the explants darkened and fragmented at a faster rate. The chemical compositions of the poly(anhydride imide) explants were also monitored using IR spectroscopy. The residual amount of anhydride bonds in the polymer backbone following implantation were calculated from peaks specific to the anhydride bonds relative to the total amount of carbonyl bonds present. Initially, the imide (TMA-gly or PMA-ala) anhydride bonds were rapidly hydrolyzed then solubilized, followed by the slower hydrolysis of the CPH monomer anhydride bonds.

Animals↗
PubMed1999

Cyclic-imide-hydrolyzing activity of D-hydantoinase from Blastobacter sp. strain A17p-4.

The cyclic-imide-hydrolyzing activity of a prokaryotic cyclic-ureide-hydrolyzing enzyme, D-hydantoinase, was investigated. The enzyme hydrolyzed cyclic imides with bulky substituents such as 2-methylsuccinimide, 2-phenylsuccinimide, phthalimide, and 3,4-pyridine dicarboximide to the corresponding half-amides. However, simple cyclic imides without substituents, which are substrates of imidase (ie.g., succinimide, glutarimide, and sulfur-containing cyclic imides such as 2,4-thiazolidinedione and rhodanine), were not hydrolyzed. The combined catalytic actions of bacterial D-hydantoinase and imidase can cover the function of a single mammalian enzyme, dihydropyrimidinase. Prokaryotic D-hydantoinase also catalyzed the dehyrative cyclization of the half-amide phthalamidic acid to the corresponding cyclic imide, phthalimide. The reversible hydrolysis of cyclic imides shown by prokaryotic D-hydantoinase suggested that, in addition to pyrimidine metabolism, it may also function in cyclic-imide metabolism.

Amidohydrolases↗