Showing papers on "Derivative (chemistry) published in 1994"
TL;DR: A high-yield synthesis of the p-methoxybenzylidene-protected docetaxel (Taxotere) side chain and the C-4 and C-5 stereocentes of the 1,3-oxazolidine are generated with complete (≥99%) stereocontrol whereas that at C-2 is produced with 96% selectivity.
Abstract: A high-yield synthesis of the p-methoxybenzylidene-protected docetaxel (Taxotere) side chain, a useful derivative for efficient, epimerization-free esterification of the 7,10-bis[(trichloroethoxy)carbonyl] derivative of 10-desacetylbaccatin III for the preparation of docetaxel, has been effected; the C-4 and C-5 stereocentes of the 1,3-oxazolidine are generated with complete (≥99%) stereocontrol whereas that at C-2 is produced with 96% selectivity
179 citations
TL;DR: The phases AFeIIFeIII(C2O4)3(A = NPrn4; NBun4; PPh4) have been synthesised and characterised chemically, structurally and magnetically; they behave as ferrimagnets, but the tetrabutylammonium salt shows a highly unusual negative magnetisation at low temperature.
Abstract: The phases AFeIIFeIII(C2O4)3(A = NPrn4; NBun4; PPh4) have been synthesised and characterised chemically, structurally and magnetically; they behave as ferrimagnets, but the tetrabutylammonium salt shows a highly unusual negative magnetisation at low temperature.
160 citations
TL;DR: A novel protein derivative has been found during process development of biosynthetic human growth hormone; it has been characterised as human growth hormones with a Cys182-Cys189 trisulphide bridge.
Abstract: A novel protein derivative has been found during process development of biosynthetic human growth hormone; it has been characterised as human growth hormone with a Cys182-Cys189 trisulphide bridge. We have not been able to find a previous report in the literature about this kind of derivative. The characterisation was obtained partly on the full-length derivative and partly on a tryptic fragment of the derivative. The full-length derivative was characterised by reduction with 1,4-dithiothreitol followed by electrospray mass spectrometry, treatment with cysteine and measurement of hydrogen sulphide liberation upon cysteine treatment. The tryptic fragment from peptide mapping was characterised by amino acid analysis, amino acid sequencing and mass spectrometry. All data indicated an extra sulphur atom in the Cys182-Cys189 cystine bridge.
86 citations
83 citations
TL;DR: Various chiral stationary phases were investigated in sub- and supercritical fluid chromatography for the separation, without derivatization, of basic (beta-blockers, benzodiazepines) and acidic (nonsteroidal anti-inflammatory drugs, beta-agonists) pharmaca.
Abstract: Various chiral stationary phases were investigated in sub- and supercritical fluid chromatography for the separation, without derivatization, of basic (beta-blockers, benzodiazepines) and acidic (nonsteroidal anti-inflammatory drugs, beta-agonists) pharmaca. For all racemates, baseline separation was achieved within short analysis times. For several solutes, the high resolution obtained allowed injection of milligram amounts and semipreparative collection of the enantiomers. The parameters affecting enantioselectivity (column efficiency, influence of modifiers and basic or acidic additives, and temperature) have been studied. Enantiomerization of 3-OH-benzodiazepines could be suppressed by working at low temperatures or by using acetonitrile as a comodifier. Serial coupling of different chiral stationary phase columns resulted in a column triplet (Chiralpak AD, an amylose derivative; Chiralcel OD, a cellulose derivative; and Chirex 3022, a Brush-type with pi-donor characteristics) on which all solutes investigated could be baseline separated.
76 citations
TL;DR: The alkyl group of the N-alkoxycarbonyl was shown to influence the yield and a new serinal derivative was cross coupled with n-pentadecanal to give a derivative of xylo-D-C 18 -phytosphingosine.
Abstract: Slow addition of 2-[N-(alkoxycarbonyl)amino] aldehydes to mixtures of [V 2 Cl 3 (THF) 6 ] 2 [Zn 2 Cl 6 ] and aliphatic aldehydes gave syn,syn-3-[N-(alkoxycarbonyl)amino] 1,2-diols in good yield and high enantiomeric purity (>99:1). The alkyl group of the N-alkoxycarbonyl was shown to influence the yield: Me >allyl>Bn>t-Bu. Only the syn,syn diastereomer was observed (>20:1), except with N-Cbz-alaninal (10:1:1), O-benzyl-N-Cbz-serinal (7:1), and N-Cbz-prolinal (5:1 to 12:1). A new serinal derivative, N-Cbz-O-TBS-serinal, was cross coupled with n-pentadecanal to give a derivative of xylo-D-C 18 -phytosphingosine
74 citations
TL;DR: The 3,4-dimethyl analogue 1b was generated by vacuum pyrolysis of 5-silaspiro[4.4]nona-2,7-diene and 2,3,7,8-tetramethyl derivative of 5a as mentioned in this paper.
Abstract: Vacuum pyrolysis of 5-silaspiro[4.4]nona-2,7-diene (5a), UV irradiation of silacyclopent-3-ene (6), and vacuum pyrolysis of 6 resulted in the formation of 1-silacyclopenta-2,4-diene (1a) characterized by its IR and UV-vis spectra. The 3,4-dimethyl analogue 1b was generated by vacuum pyrolysis of 5b, the 2,3,7,8-tetramethyl derivative of 5a. Photoreversible interconversion of 1a with 1-silacyclopent-3-ene-1,1-diyl (2a) 1-silacyclopenta-1,3-diene (3a), and 1-silacyclopenta-1,4-diene (4a) and the analogous interconversion of 1b with 3,4- dimethyl-1-silacyclopent-3-ene-1,1-diyl (2b), 3,4-dimethyl-1-silacyclopenta-1,3-diene (3b), and 1,3-dimethyl-1-sila cyclopenta-1,4-diene (4b) have been observed upon irradiation at selected wavelengths
73 citations
TL;DR: It is demonstrated unambiguously that the large structure change is induced primarily by the polar solvent rather than by complex formation with cyclophilin.
70 citations
65 citations
Patent•
28 Sep 1994
TL;DR: Arylenediamine derivative can remarkably improve the luminescence life when used as a component of an organice electroluminescent (EL) element as discussed by the authors, which can be used to improve the performance of an organic EL element.
Abstract: An organic electroluminescent (EL) element improved in luminescence life as compared with the conventional ones, and a novel arylenediamine derivative which can remarkably improve the luminescence life when used as a component of an organice EL element. Examples of the EL element are one containing at least a p-phenylenediamine derivative having at least six benzene rings and one containing at least a 4,4'-biphenylenediamine derivative having five biphenyl groups. Examples of the arylenediamine derivative are a p-phenylenediamine derivative having four biphenyl groups and a 4,4'-biphenylenediamine derivative having five biphenyl groups.
65 citations
Patent•
12 Aug 1994
TL;DR: In this article, a new compound capable of providing a long-lived organic electroluminescent element having a high luminous efficiency and brightness was obtained by carrying out the substitution reaction of a 9,10-dihalogenoanthracene of formula III (X is a halogen) with a diarylamine compound of formula IV such as 2-methyl-4-methoxy-diphenylamine in a molar amount of, e.g.
Abstract: PURPOSE:To obtain a new compound capable of providing a long-lived organic electroluminescent element having a high luminous efficiency and brightness and an electrophotographic photoreceptor good in electrophotographic characteristics due to its excellent positive hole transport ability. CONSTITUTION:A compound of formula I [R to R are each H, a halogen. a (substituted)alkyl, etc.], e.g. a compound of formula II. This compound is obtained by carrying out the substitution reaction of a 9,10-dihalogenoanthracene of formula III (X is a halogen) such as 9,10-dibromoanthracene with a diarylamine compound of formula IV such as 2-methyl-4-methoxy-diphenylamine in a molar amount of, e.g. 2-3 times based on the compound of formula III in nitrobenzene solvent in the presence of a base such as potassium carbonate and a catalyst such as copper powder.
Journal Article•
TL;DR: In this article, a cyclotrimerization of 4,5-bis(hexylthio)phthalodinitrile (1) in 1-chloronaphthalene in the presence of BCl 3 leads to the subphthalocyanine 4.
Abstract: Cyclotrimerization of 4,5-bis(hexylthio)phthalodinitrile (1) in 1-chloronaphthalene in the presence of BCl 3 leads to the subphthalocyanine 4. Unsymmetrical phthalocyanines (5, 6) with six alkylthio substituents on three of the benzenoid units are synthesized by the reaction of 4 with an diiminoisoindoline derivative (R'=H or NO 2 ). These extremely soluble compounds are characterized by IR, 1 H- and 13 C-NMR as well as UV/Vis spectra
Patent•
18 Feb 1994
TL;DR: A novel PF1022 derivative as a cyclic depsipeptide, represented by general formula (I), or a salt thereof, having the vermifugal activity against various parasites living in man, domestic and pet animals, and the like and thus being useful as a vermicide for preventing or treating infectious diseases caused by parasites as mentioned in this paper.
Abstract: A novel PF1022 derivative as a cyclic depsipeptide, represented by general formula (I), or a salt thereof, having the vermifugal activity against various parasites living in man, domestic and pet animals, and the like and thus being useful as a vermicide for preventing or treating infectious diseases caused by parasites. In formula (I) R?1, R2, R3 and R4? represent each independently alkyl, cyclohexylmethyl, optionally substituted benzyl, etc; and X, Y, Z and Q represent each independently methyl or hydrogen, excluding the case where all of the R1, R3, X, Y, Z and Q represent methyl groups and R?2 and R4? represent benzyl groups at the same time.
TL;DR: In this article, 1-(tert-butyldimethylsilyl)-3-lithioindole (2) is prepared by metalation of the corresponding 3-bromo derivative 1 and efficiently reacts with electrophiles to give 3-substituted indoles 3 and 4
Abstract: 1-(tert-Butyldimethylsilyl)-3-lithioindole (2) is prepared by metalation of the corresponding 3-bromo derivative 1 and efficiently reacts with electrophiles to give 3-substituted indoles 3 and 4
TL;DR: Diethynylmethanobuckminsterfullerene has been prepared by reaction of the lithium salt of 1,5-bis(trimethylsilyl)-1,4-pentadiyn-3-one (p-toluenesulfonyl) hydrazone with C{sub 60} followed by desilylation as discussed by the authors.
Abstract: Diethynylmethanobuckminsterfullerene has been prepared by reaction of the lithium salt of 1,5-bis(trimethylsilyl)-1,4-pentadiyn-3-one (p-toluenesulfonyl) hydrazone with C{sub 60} followed by desilylation The derivative was structurally characterized by NMR, IR, UV-vis, and CI-TQMS spectroscopies
TL;DR: In this article, a most straightforward and efficient synthesis of this antigen series is exhibited, which could be readily transformed into target molecules 1a-c and 2b,c, respectively.
TL;DR: It is argued that the circumstances of formation of this oxyferryl species are the same as those for the P form of cytochrome c oxidase, a species often regarded as containing a bound peroxide ion.
Abstract: Oxidized cytochrome bo reacts rapidly with micromolar concentrations of H2O2 to form a single derivative The electronic absorption spectrum of this compound differs from that of the oxidized form of the enzyme reported by this laboratory [Watmough, Cheesman, Gennis, Greenwood and Thomson (1993) FEBS Lett 319, 151-154] It is characterized by a Soret maximum at 411 nm, increased absorbance at 555 nm, and reduced intensity at 624 nm The apparent dissociation constant for this process is of the order of 4 x 10(-6) M, and the bimolecular rate constant for the formation of the new compound is (125-17) x 10(3) M-1s-1 Electronic absorption difference spectroscopy shows this product to be identical with the compound formed from the reaction of the mixed-valence form of the enzyme with dioxygen Investigation of this compound by room-temperature magnetic cd spectroscopy shows haem o to be neither high-spin nor low-spin ferric, but to have a spectrum characteristic of an oxyferryl species There is no evidence for oxidation of the porphyrin ring Therefore the binuclear centre of this species must consist of an oxyferryl haem (S = 1) coupled to a Cu(II) ion (S = 1/2) to form a new paramagnetic centre The reaction was also followed by X-band epr spectroscopy, and this showed the disappearance in parallel with the formation of the oxyferryl species, of the broad g = 37, signal which arises from the weakly coupled binuclear centre in the oxidized enzyme Since no new epr-detectable paramagnetic species were observed, the Cu(II) ion is presumed to be coupled to another paramagnet, possibly an organic radical There is no evidence in the electronic absorption spectrum to indicate further reaction of cytochrome bo with H2O2 to form a second species We argue that the circumstances of formation of this oxyferryl species are the same as those for the P form of cytochrome c oxidase, a species often regarded as containing a bound peroxide ion The implications of these observations for the reaction mechanism of haem-copper terminal oxidases are discussed
Patent•
21 May 1994
TL;DR: In this paper, the structural formula of STR1 is used to inhibit the enzymatic activity of proteolytic enzymes, and processes for preparation thereof, method of use thereof in treatment of degenerative diseases and pharmaceutical compositions thereof are disclosed.
Abstract: Compounds having the structural formula ##STR1## which inhibit the enzymatic activity of proteolytic enzymes, and processes for preparation thereof, method of use thereof in treatment of degenerative diseases and pharmaceutical compositions thereof are disclosed.
TL;DR: The furan derivative undergoes diastereoselective Diels-Alder reac- tions with dienophilic species such as α, β-unsaturated esters, nitriles, sulfones, and imides in good to excellent chemical yields.
Abstract: The furan derivative (1) undergoes diastereoselective Diels-Alder reac- tions with dienophilic species such as α,β-unsaturated esters, nitriles, sulfones, and imides in good to excellent chemical yields. The oxobi- cyclic adducts obtained are amenable to chemical transformations which render them useful to natural product synthesis
Patent•
10 Feb 1994
TL;DR: A phosphonic diester derivative represented by general formula (1) has the effect of reducing blood sugar and lipid levels, and so forth, and is useful for treating diabetes, hyperlipidemia, and the like as discussed by the authors.
Abstract: A phosphonic diester derivative represented by general formula (1). It has the effect of reducing blood sugar and lipid levels, and so forth, and is useful for treating diabetes, hyperlipidemia, and the like.
TL;DR: Caffeine and ryanodine, which mobilize Ca from internal stores in many cell types, induced Ca sequestration into an IP3-insensitive store of gastric cells, and caffeine caused a reduction in cytoplasmic [Ca] (as measured with fura 2).
Abstract: When loaded as the acetoxymethyl ester (AM) derivative, the fluorescent probe mag-fura 2 accumulates in both the cytoplasm and the subcellular compartments. The relatively high dissociation constan...
TL;DR: In this paper, the palladium-catalysed couplings of a γ-tri-n-butylstannylally-glycine derivative and an E-δ-tri-, n- butylstanyl-ally-lgine derivative with various organic electrophiles are described.
TL;DR: In this article, a key intermediate was prepared via successive glycosidations of 1,6-anhydro maltose derivative 8 with glycosyl donors 6 and then with 11, cyclized under a diluted condition, and deprotected to give the title compound.
TL;DR: It is proposed that 2 is mainly responsible for the formation of these new products of nifedipine by photochemical condensation.
Patent•
23 Dec 1994TL;DR: In this article, a peroxygen-containing compound is used for epoxy-containing compounds, which are essentially free of organic halides and are useful in coatings, castings, laminates etc.
Abstract: Epoxy-containing compounds which are essentially free of organic halides are prepared by (I) reacting an allyl derivative of an active hydrogen-containing compound with (II) a peroxygen-containing compound. The epoxy-containing compounds are useful in coatings, castings, laminates etc.
Patent•
05 Dec 1994TL;DR: Water-in-oil emulsions are described in this paper, which consist of water, polysiloxane polyalkyl polyether copolymer and a phthalic anhydride derivative.
Abstract: Water-in-oil emulsions are disclosed that comprise: a) water; b) from about 10 to 65 % by weight of an oil; and c) an emulsification system comprising a polysiloxane polyalkyl polyether copolymer and a phthalic anhydride derivative, substantially permanently maintaining the water and oil as an emulsion, the emulsification system being substantially free from aluminum and zirconium salts, the emulsion being at a pH of from about 5 to 10.