摘要:

An original method for the phosphorylation of an unprotected myo-inositol is described, which yields several myo-inositol phosphates at the same time. The reaction proceeds via a partial or complete phosphoranylation of the cyclitol by means of the aminobicyclophosphane8, followed by oxidation of the resulting bicyclophosphoranes bearing a P—H bond and acid hydrolysis of the neutral phosphates thus formed. In the case of the tris-phosphoranylation we identified, among the HPLC fractions, the myo-inositol-1,2-(cycl)phosphate22, the myo-inositol-1-phosphate23, and the myo-inositol-2-phosphate24.

ISSN:0008-4042    

DOI:10.1139/v88-461

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Penta-O-acetyl-D-glucose diethyl dithioacetal monoxide3was obtained by oxidation of penta-O-acetyl-D-glucose diethyl dithioacetal2with 3-chloroperbenzoic acid. By reaction of3with sodium methoxide in methanol and further acetylation, 3,4,6-tri-O-acetyl-2,5-anhydro-D-mannose-diethyl dithioacetal monoxide8and the reduction product 3,4,6-tri-O-acetyl-2,5-anhydro-1,1-bis(ethylthio)-1-deoxy-D-arabino-hex-1-enitol4were obtained. Reduction of8yielded the corresponding dithioacetal derivative9, which was converted to 3,4,6-tri-O-acetyl-2,5-anhydro-D-mannose diethyl acetal11.

ISSN:0008-4042    

DOI:10.1139/v88-462

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The crystal and molecular structures of two ligands for the benzodiazepine (BZ) receptor,t-butyl β-carboline-3-carboxylate,I(C16H16N2O2), and 2-(methoxycarbonyl)canthin-6-one,II(C16H10N2O3), are reported. Thet-butyl β-carboline compound has high affinity for the receptor and is an antagonist; in contrast, the canthin-6-one has a 10-fold lower affinity for the receptor and no determinableinvivoactivity. The space group forIisP21/cwitha = 11.756(1),b = 11.2324(8),c = 11.964(1) Å, and β = 105.99(1)°. ForII, the space group is alsoP21/cwitha = 9.317(1),b = 7.964(1),c = 17.180(3) Å, and β = 104.173(7)°. The orientation of the alkyl-carboxylate side chain is different in the two molecules and may be related to the difference in affinity andinvivoactivity of the ligands. In addition, the packing arrangements in the two structures are dominated by π-stacking interactions; and, in the case of thet-butyl compound, by hydrogen bonding.

ISSN:0008-4042    

DOI:10.1139/v88-463

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The naphthaloyl group has been found to be a selective amino protecting group for deoxycytidine, deoxyadenosine, and deoxyguanosine in oligodeoxyribonucleotide synthesis. All three protected monomers obtained (78–85%), being six-membered cyclic imides, were fairly stable. These protected monomers were used successfully for the preparation of dimers (phosphodiester approach) and tetramers (phosphotriester approach) in solution as well as solid phase, respectively. The group acted as a purification tool due to its high lipophilicity. No adverse effect has been observed either on the glycosidic bond (depurination) or the internucleotidic bond during its removal. The monomeric units were characterized by UV, NMR, and elemental analyses whereas the tetramers were characterized by enzymatic hydrolyses with snake venom phosphodiesterase followed by alkaline phosphatase.

ISSN:0008-4042    

DOI:10.1139/v88-464

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Modelling of the binding step in dopamine receptor–antagonist interactions was undertaken using sixteen antagonists belonging to the following five chemical series: phenothiazines, thioxanthenes, butyrophenones, benzamides, and benzisoxazoles. The Lower Unoccupied Molecular Orbitals (LUMOs) of the antagonists used for these interactions were compared using a similarity τijindex, which enabled us to define the characteristic orbital forms of the active molecules. The result of the intersection of these representative orbital forms was the form common to the antagonists' LUMOs. This form corresponds to the orbital form of the indole's Higher Occupied Molecular Orbital (HOMO), and thus suggests that the aromatic binding site of the dopamine receptor is part of a tryptophan type structure.

ISSN:0008-4042    

DOI:10.1139/v88-465

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The 500 MHz1H and 125 MHz13C spectra of ergosteryl and 7-dehydrocholesteryl acetate were recorded in C6D6and CDCl3and assigned using two-dimensional NMR techniques. It is shown that incorporation of an Fe(CO)3or a Rh(acac) moiety onto the ring B diene system affects the chemical shifts of neighbouring protons and carbons. These changes are discussed in terms of the anisotropic properties of the organometallic fragments.

ISSN:0008-4042    

DOI:10.1139/v88-466

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Direct irradiation of acetonitrile–methanol (3:1) solutions of 1,4-dicyanobenzene and the cyclic olefins, cyclohexene, 1-methylcyclohexene, norbornene, and 2-methylnorbornene, leads to formation of regio- and stereoisomers of the 1:1:1 (alcohol:olefin:aromatic) adducts. This reaction can be photosensitized by electron transfer; addition of electron donors, biphenyl or phenanthrene, to the irradiation mixture generally increases the efficiency and yield of adduct formation. The efficiency of the reaction and the ratio of isomeric adducts are also affected by the addition of salts, particularly magnesium perchlorate. All of the possible regio- and stereoisomers from cyclohexene and 1-methylcyclohexene have been identified, two from cyclohexene and four from 1-methylcyclohexene. Three of the four possible isomers from norbornene were characterized; theendo,endoisomer was not detected. There are eight possible isomers from 2-methylnorbornene; six were detected and five have been isolated and identified. The two sterically hindered isomers, those having both the 4-cyanophenyl and the methoxy groups in theendoposition, andexo-3-(4-cyanophenyl)-endo-2-methoxy-exo-2-methylnorbornane, were not characterized. The structures of the products were established largely on the basis of the1H and13C nuclear magnetic resonance spectra. The mechanism of the reaction is discussed, with emphasis on those factors that may affect the product ratio. The most striking observation is that the reaction is regioselective when magnesium perchlorate is added to the irradiation mixture.

ISSN:0008-4042    

DOI:10.1139/v88-467

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Rate constants have been measured for the hydrolysis of sixp-nitrophenyl alkanoates (C2, C4, C6, C8, C10, and C12) in basic aqueous media containing up to 80% (v/v) of the cosolvents: ethylene glycol (EG), 2-methoxyethanol (2ME), 1,2-dimethoxyethane (DME, glyme), bis(2-methoxyethyl) ether (diglyme), or DMSO. Addition of these cosolvents reduces and ultimately removes hydrophobic aggregation and coiling of the longer chain alkanoates, with the ether-type solvents (2ME, DME, and diglyme) being more efficient than EG or DMSO. Once the rate-lowering effects of aggregation and coiling have been removed by addition of a cosolvent, the rates of hydrolysis of the C4–C12 esters are all virtually the same, in a given medium. Thus, the apparent "steric size" of the C4–C12 (and even C16) acyl chains does not differ significantly in basicp-nitrophenyl ester hydrolysis. Addition of DMSO brings about rate increases that are greater in a carbonate buffer (pH 10.48) than those in 0.05 M NaOH solution, and these increases are larger than those observed for ethyl acetate in 0.05 M NaOH solution. None of the rate increases rise as quickly as the enhanced basicity of aqueous DMSO media.

ISSN:0008-4042    

DOI:10.1139/v88-468

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Oil/water interfacial tensions are reported for systems containing pure alkane, aqueous sodium chloride, and a pure anionic surfactant, either Aerosol OT orp-dihexylbenzene sodium sulphonate (DHBS). Evidence is produced to support the claim that monolayer adsorption at the oil/water interface can produce ultralow tensions (~ 1 µN m−1), and that the presence at the interface of a third, surfactant-rich phase is not necessary. The aggregation of DHBS and its distribution between oil and aqueous phases of various salinities have been investigated. It has been confirmed that the behaviour of DHBS in these respects is similar to that of Aerosol OT, as might be expected from its molecular structure. The sizes of microemulsion droplets in equilibrium with planar adsorbed monolayers have been determined, and related to the tensions of the plane oil/aqueous phase interfaces using simple existing theory.

ISSN:0008-4042    

DOI:10.1139/v88-469

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

We have determined thermodynamic parameters for the solution and ionization in dimethylsulfoxide and water of four aminosulfonic acids: NH2(CH2)nSO3H withn = 0,1, and 2, and NH2C6H4SO3H. Potentiometric and calorimetric methods were used. The solubilities of the four acids in Me2SO are either nearly equal to or lower than in water, but the enthalpies of solution are 15–40 kJ mol−1more exothermic in Me2SO. The three aliphatic acids are much weaker (2.1 ≤ ΔpKa ≤ 5.5) in Me2SO than in water and their heats of ionization are some 30 kJ mol−1more endothermic in Me2SO. The discussion of our results is based on comparisons with corresponding data for related substituted amines and ammonium ions, and sulfonic acids and sulfonate ions. We conclude that the four aminosulfonic acids are mostly present as zwitterions in Me2SO just as in water.

ISSN:0008-4042    

DOI:10.1139/v88-470

出版商:NRC Research Press    

年代:1988

数据来源: NRC