Showing papers on "Derivative (chemistry) published in 1993"

Synthesis of a fullerene derivative for the inhibition of HIV enzymes

Abstract: A diamido diacid diphenyl fulleroid derivative was designed specifically to inhibit an HIV enzyme. The detailed synthesis and mass spectrometric analysis of the water-soluble, biologically active methanofullerene are described. The compound was prepared in three steps from C[sub 60] via a suitably diphenyldiazomethane. High-resolution mass spectrometric analysis was possible only under mild matrix-assisted laser desorption/ionization Fourier transform mass spectrometry conditions. Direct infrared or ultraviolet laser desorption resulted exclusively in observation of C[sub 60] ions, in either positive or negative mode. 13 refs., 3 figs.

C60H2: Synthesis of the Simplest C60 Hydrocarbon Derivative

Abstract: The reaction of C(60) with BH(3): tetrahydrofuran in toluene followed by hydrolysis yielded C(60)H(2). This product was separated by high-performance liquid chromatography and characterized as the addition product of H(2) to a 6,6-ring fusion (1alb isomer). The (1)H nuclear magnetic resonance (NMR) spectrum of the product remained a sharp singlet between -80 degrees and +100 degrees C, which suggests a static structure on the NMR time scale. Hydrolysis of the proposed borane addition product with acetic acid-d(1) or D(2)O yielded C(60)HD, and its (3)J(HD) coupling constant is consistent with vicinal addition. The observation of a single C(60)H(2) isomer is in complete agreement with earlier calculations that indicated that at most 2 of the 23 possible isomers of C(60) would be observable at equilibrium at room temperature. These results suggest that organoborane chemistry may be applied to further functionalization of fullerenes.

Synthesis of a Fullerene Derivative of Benzo[18]crown‐6 by Diels‐Alder Reaction: Complexation Ability, Amphiphilic Properties, and X‐Ray Crystal Structure of a Dimethoxy‐1,9‐(methano[1,2]benzenomethano)fullerene[60] Benzene Clathrate

Abstract: A fullerene derivative 1 of benzo[18]crown-6 was obtained by Diels-Alder addition of fullerene[60](C60) to the ortho-quinodimethane prepared in situ from 4,5-bis(bromomethyl)benzo[18]crown-6 (3) with Bu4NI in toluene. Extraction experiments show that the complexation of K+ ions strongly increases the solubility of 1 in protic solvents like MeOH. Using Langmuir-Blodgett techniques, monolayers of the highly amphiphilic fullerene-derived crown ether 1 and its K+ ion complex were prepared. An X-ray crystal structure was obtained from a benzene clathrate of comparison compound 2, synthesized by Diels-Alder reaction of C60 with the ortho-quinodimethane derived from 1,2-bis(bromomethyl)-4,5-dimethoxybenzene (4). Both the fullerene molecule 2 and the benzene molecule are fully ordered in a crystal packing which is stabilized by intermolecular van-der-Waals contacts between the benzene ring and the C-spheres, intermolecular C…C contacts between the C60 moieties, and intermolecular O…C contacts between the O-atoms of the veratrole moieties and fullerene C-atoms.

Phase transfer catalyzed preparation of aromatic polyether polymers

Abstract: Aromatic polyether polymers, illustrated by polyethersulfones, polyetherketones and polyetherimides, are prepared by a phase transfer catalyzed reaction between a salt of a dihydroxyaromatic compound and a substituted aromatic compound such as bis(4-hydroxyphenyl) sulfone, bis(4-hydroxyphenyl) ketone or 1,3-bis[N-(4-chlorophthalimido)]benzene or the corresponding derivative of toluene or diphenyl ether, or the analogous fluoro-, bromo- or nitro-substituted compounds. The phase transfer catalysts employed are those which are stable at temperatures in the range of about 125-250 °C. Particularly preferred phase transfer catalysts are the hexaalkylguanidinium and α,φ-bis(pentaalkylguanidinium)alkane salts and the corresponding heterocyclic salts.

Voltammetric study on a condensed monolayer of a long alkyl cyclodextrin derivative as a channel mimetic sensing membrane

Abstract: For a fundamental study on the development of signal-amplifying chemical sensors that mimic biological ion channels, a control of membrane permeability based on the blocking of an intramolecular channel by host-guest complexation has been investigated for a condensed monolayer of a long alkyl derivative of β-cyclodextrin having a channel-like structure (6 A ,6 B ,6 C ,6 D ,6 E ,6 F ,6 G -heptadeoxy-6 A ,6 B ,6 C ,6 D ,6 E , F ,6 G -heptakis(dodecylithio)-β-cyclodextrin tetradecaacetate)

Material and method for forming image

Abstract: PURPOSE: To obtain the image forming material capable of forming an image good in both of resolution and sensitivity through a safe and simple dry processing by incorporating a specified Co complex compound and a specified dye compound in a layer on a support. CONSTITUTION: The image forming material has a layer contg. the Co complex represented by formula I and the dye represented by formula II, on the support. In formulae I and II, L is a coordination compound forming the complex compound together with a Co cation; m is an integer of 1-6, and when m is ≥2, each of plural L may be the same or different; each of R 1 -R 4 is a group combining through a carbon atom with the boron atom; n is 1, 2 or 3, and when n is ≥2, each of plural counter anions may be the same or different; D ye + is a cationic dye; and X is a counter anion. It is preferred for the image forming material that at least one of L in formula I contains the dye or dye precursor and X in formula II is a boron anion derivative. COPYRIGHT: (C)1995,JPO

Finite energy solutions of nonlinear Schrdinger equations of derivative type

Abstract: This paper is concerned with the initial value problem for nonlinear Schrodinger equations of the form \[ (\dag)\qquad \left\{ \begin{gathered} i\partial _t \psi + \partial \psi = i\lambda \partial \left( {| \psi |^2 \psi } \right) + \lambda _1 | \psi |^{p_1 - 1} \psi + \lambda _2 | \psi |^{p_2 - 1} \psi ,\quad (t,x) \in \mathbb{R} \times \mathbb{R}, \hfill \\ \psi (0,x) = \phi (x),\quad x \in \mathbb{R}, \hfill \\ \end{gathered} \right.\] where $\partial = \partial _x = {\partial /{\partial x}},\lambda ,\lambda _1 ,\lambda _2 \in \mathbb{R}$ and $2 \leq p_1 < p_2 < 5$. It is shown that if $\phi \in H^1 (\mathbb{R})$ and $\| \phi \|_2^2 < {{2\pi } /{| \lambda |}}$, then there exists a unique global solution $\psi $ of (†) such that $\psi \in C(\mathbb{R};H^1 (\mathbb{R}))$. This paper introduces a new method to obtain the result.

5-o-desosaminylerythronolide a derivative

Abstract: A novel macrolide antibiotic having a potent antibacterial activity, 11-amino-3,11-dideoxy-3-oxo-5-O-desosaminyl-6-O-methylerythronolide A 11-N, 12-O-cyclic carbamate represented by formula (I), and a pharmaceutically acceptable acid addition salt thereof.

Depsipeptide derivative, production thereof and use thereof

Abstract: A compound represented by general formula (I) or a salt thereof, excellent in parasiticidal activity as an enthelmintic for animal and man, wherein A represents benzyl which is appropriately substituted or phenyl which may be appropriately substituted; Aa represents benzyl or phenyl each of which may be appropriately substituted; B and D represent each lower alkyl; and C represents hydrogen or lower alkyl.

Potent HIV protease inhibitors: the development of tetrahydrofuranylglycines as novel P2-ligands and pyrazine amides as P3-ligands.

Abstract: A series of protease inhibitors bearing constrained unnatural amino acids at the P2-position and novel heterocycles at the P3-position of compound 1 (Ro 31-8959) were synthesized, and their in vitro enzyme inhibitory and antiviral activities were evaluated. Replacement of P2-asparagine of compound 1 with (2S,3'R)-tetrahydrofuranylglycine resulted in improvement in enzyme inhibitory as well as antiviral potencies (compound 23). Interestingly, incorporation of (2S,3'S)-tetrahydrofuranylglycine at the P2-position proved to be less effective. The resulting compound 24 was 100-fold less potent than the 2S,3R-isomer (compound 23). This stereochemical preference indicated a hydrogen-bonding interaction between the tetrahydrofuranyl oxygen and the residues of the S2-region of the enzyme active site. Furthermore, replacement of P3-quinolinoyl ligand of 1 with various novel heterocycles resulted in potent inhibitors of HIV proteases. Of particular interest, compound 2 with (2S,3'R)-tetrahydrofuranylglycine at P2 and pyrazine derivative at P3 is one of the most potent inhibitors of HIV-1 (IC50 value 0.07 nM) and HIV-2 (IC50 value 0.18 nM) proteases. Another important result in this series is the identification of compound 27 in which the P2-P3-amide carbonyl has been removed. The resulting compound 27 has exhibited improvement in antiviral potency while retaining the enzyme inhibitory potency similar to compound 1.

Modified taxols. 10. Preparation of 7-deoxytaxol, a highly bioactive taxol derivative, and interconversion of taxol and 7-epi-taxol

Abstract: Deoxygenation of taxol at C-7 can be achieved through its S-methyldithiocarboxy derivative 3 to yield a product which is more cytotoxic than taxol to P-388 cells

HIV inhibitory natural products. 11. Structure, absolute stereochemistry, and synthesis of conocurvone, a potent, novel HIV-inhibitory naphthoquinone trimer from a Conospermum sp

Abstract: Bioassay-guided fractionation provided conocurvone (1), a novel trimeric naphthoquinone derivative, as the active anti-HIV constituent of an extract from a Conospermum sp. The related naphthoquinone monomer teretifolione B (2) also was isolated from a Conospermum sp. extract. The absolute stereochemistry of 2 was established by X-ray crystallographic analysis of the p-bromobenzoate derivative 6. Base-catalyzed coupling of 2 equiv of teretifolione B (2) with the deoxy derivative 8 provided compound 1, which was identical in all respects with the natural product

Toward organic synthesis of a magnetic particle: dendritic polyradicals with 15 and 31 centers for unpaired electrons

Abstract: Starting from a bromo triether derivative 1, we prepared a homologous pentadecaether, which is a precursor for the title pentadecaradical, by repeating twice the following twostep procedure (total of four steps): (1) Br/Li exchange followed by the addition of the organolithium to a benzoic acid ester derivative and (2) conversion of the triarylmethyl alcohol to methyl ether. Similarly, a 31-ether precursor was prepared by repeating three times the above sequence (total of six steps). The polyethers were converted with lithium metal in THF to the corresponding carbopolyanions and, subsequently, oxidized with iodine at 180 K to give the polyradicals

The crystal structure, absolute configuration, and phosphodiesterase inhibitory activity of (+)-1-(4-bromobenzyl)-4-(3-(cyclopentyloxy)- 4-methoxyphenyl)-pyrrolidin-2-one.

Abstract: Chiral HPLC resolution of the phosphodiesterase IV (PDE IV) inhibitor rolipram (1) provided (-)-1, and this enantiomer was converted into its 1-(4-bromobenzyl) derivative, (+)-2. X-ray structural analysis of (+)-2 established the absolute configuration as R, which provides the first direct evidence for a previously assumed assignment of configuration. The crystal structure of (+)-2 and the PDE inhibitory activity of both enantiomers of 2 are discussed in the context of a previously proposed topological model.

Synthesis of a Fullerene Derivative for the Inhibition of HIV Enzymes.

Abstract: A diamido diacid diphenyl fulleroid derivative was designed specifically to inhibit an HIV enzyme. The detailed synthesis and mass spectrometric analysis of the water-soluble, biologically active methanofullerene are described. The compound was prepared in three steps from C[sub 60] via a suitably diphenyldiazomethane. High-resolution mass spectrometric analysis was possible only under mild matrix-assisted laser desorption/ionization Fourier transform mass spectrometry conditions. Direct infrared or ultraviolet laser desorption resulted exclusively in observation of C[sub 60] ions, in either positive or negative mode. 13 refs., 3 figs.

Theoretical studies of the 2- and 4-hydroxybenzoic acid with competing hydrogen bonds in the gas phase and aqueous solution

Abstract: MP2/6-31G * //6-31G * ab initio quantum chemical calculations in the gas phase and Monte Carlo simulations for isothermal-isobaric (NPT) ensembles in aqueous solution have been carried out for 2- and 4-hydroxybenzoic acid. After total geometry optimization of eight planar conformers for the 2-OH derivative and four conformers for the 4-OH derivative in the gas phase, the structure with the 2-OH phenolic hydroxyl with an intramolecular hydrogen bond to the carbonyl oxygen was found to be the most stable conformer. Normal frequency analyses were carried out using the 6-31G * optimized geometries, and thermal corrections were obtained at 298 K and 1 atm

Amarulone, a Novel Cyclic Hydrolysable Tannin from Phyllanthus amarus

Abstract: A novel cyclic metabolite named amarulone (1) was isolated from Phyllanthus amarus and its structure was elucidated by spectra analysis of its phenazine derivative (2).

Trifluoromethyl-Containing Transition Metal Complexes

Abstract: Publisher Summary This chapter examines the current status of the chemistry of trifluoromethyl—containing transition metal compounds where the term “transition metal” had been defined to include the metals of groups. The CF3 ligand is a desirable ligand for many applications in both organic and inorganic chemistry. In transitional metal organometallic chemistry, the substitution of a CF3 group for a CH3 group commonly dramatically improves the thermal, oxidative, and hydrolytic stability of the product. The first trifluoromethyl, containing derivative of a d block element was formed when Mn(CO)5(COCF3) was thermally decarbonylated to give Mn(CO)5(CF3). This chapter reviews some of the early results that were reported in the trifluoromethyl transition metal area. The survey is followed by a discussion of more recent studies, which is presented by group of the periodic table. This chapter focuses the X-ray crystallographic data that have been obtained, while it indicates some aspects of the importance of trifluoromethyl transition metal chemistry and its future.

Direct synthesis of a polyoxometallate-pillared layered double hydroxide by coprecipitation

Abstract: The Coprecipitation reaction of Zn2+ and Al3+ ions in moderately acidic α-[SiW11O39]8– solution directly affords a layered double hydroxide derivative with an approximate composition of [Zn24Al8(OH)64][α-SiW1lO39] and an exceptionally well-ordered gallery height of 9.8 A.

Serendipitous synthesis of a cyclopropane-containing taxol analog via anchimeric participation of an unactivated angular methyl group

Abstract: Treatment of a 7-epi taxol derivative with DAST in dichloromethane led to an unexpected reaction involving participation of the C-19 methyl group and clean formation of a cyclopropane ring

Novel carbostyril derivative

Abstract: A carbostyril derivative represented by general formula (I), which selectively acts upon β2-adrenaline receptor, and a pharmacologically acceptable salt thereof, wherein -OY represents hydroxy, lower alkoxy or protected hydroxy; Z represents hydrogen, hydroxy, alkoxy or -OCH2-A; A represents lower alkoxycarbonyl, N-(un)substituted carbamoyl, or linear alkylene substituted by lower alkoxycarbonyl or hydroxy; the broken line between the 3- and the 4-positions indicates that the bond therebetween is either single or double.

Radical additions to 7-oxabicyclo[2.2.1]hept-5-en-2-one. Facile preparation of all-cis-Corey lactone

Abstract: Regioselective addition of a malonyl radical to 7-orabicyclo[2.2.1]hept-5-en-2-one followed by rearrangement of the radical adduct was used as a key step for the synthesis of all-cis-Corey lactone, cyclopenta[b]furan-2-one derivative, a potent intermediate for the preparation of prostaglandins and 12-epi-prostaglandins