Total synthesis of (+)-zaragozic acid C

A total synthesis of (+)-zaragozic acid C is described. Key features of the synthesis are the use of a double Sharpless asymmetric dihydroxylation reaction of diene 6 to control stereochemistry at four contiguous stereocenters from C3 to C6; the introduction of the C1-side chain by reaction between the anion derived from the dithiane monosulfoxide 27 and the core aldehyde 12; a high yielding, acid-mediated simultaneous acetonide deprotection-dithiane removal-ketalization procedure leading exclusively to the 2, 8-dioxabicyclo[3.2.1]octane core 34; and a novel triple oxidation procedure allowing installation of the tricarboxylic acid.     

Modelisation Des Nappes De Solubilite Du Diagramme De Phases Mg(NO3)2–Al(NO3)3–H2O

A program has been written to describe solubility surfaces of the polythermal ternary phase diagram Mg(NO₃)₂–Al(NO₃)₃–H₂O, using the model proposed by Cohen-Adad et al. [2]. In this work we present the calculation of the solubility surface of Mg(NO₃)₂×6H₂O and Al(NO₃)₃×9H₂O in the phase diagram. The calculated isothermal sections are in a good agreement with experimental determinations. Coefficients of the fitting equation that describes the solubility field allow drawing any isothermal section. The monovariant line was also calculated. The chosen model is well adapted to calculations of these solubility surfaces and gives very good results. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and Stereochemistry of Novel Dibrominated 1,5-Dioxaspiro[5.5]undecane Derivatives

Summary.  The synthesis and stereochemistry of new dibrominated spiro-1,3-dioxane derivatives are reported. Investigations by means of NMR methods and single crystal X-ray diffraction for two compounds revealed the high regio- and diastereoselectivity of the bromination reaction of some new spiro-1,3-dioxanes and the asymmetric induction of the chiral carbon atom located in the spiro skeleton. Received July 13, 1999. Accepted October 21, 1999     

Potentiometric and visual titrations with bromamine-B

Bromamine-B is proposed as an oxidimetric titrant for potentiometric and visual end-point titrations of arsenic(II), hexacyanoferrate(II), antimony(III), hydroquinone, semicarbazide hydrochloride, isonicotinic acid hydrazide, hydrazine sulphate, ascorbic acid, phenylhydrazine hydrochloride and metol. Quinoline Yellow, naphthidine, dimethylnaphthidinedisulphonic acid, o-dianisidine, diphenylbenzidine, Variamine Blue, alpha-naphthoflavone, Amaranth, Methyl Orange and Methyl Red are proposed as indicators in macro and micro titrations of the reductants with bromamine-B. The transition potentials of Quinoline Yellow, naphthidine, dimethylnaphthidinedisulphonic acid, and o-dianisidine in the titration of ascorbic acid are reported. Arsenic(III) and hexacyanoferrate(II) are suggested for the standardization of bromamine-B solutions.     

Preparation and application of functional polymers—II. Preparation of vinyl ethers and thioethers using polymer-supported phosphonium salts

Insoluble polystyryldiphenyl-methoxymethyl- and methylthiomethyl-phosphonium chlorides have been prepared by treating polystyryldiphenylphosphine with chloromethylmethyl-ether and thioether respectively. These reagents were used for the conversion under mild conditions of carbonyl compounds into vinyl-ethers and thioethers, otherwise difficult to obtain; yields are high and work-up is easy. Moreover, methyl and ethyl β-styryl ethers were also prepared from the polymeric phosphorane by treatment with formate esters.     

Structural chemistry of azo complexes

Summary Complexes of Co^II, Ni^II, Cu^II, Pd^II, and Pt^IV with 2,4,5-trihydroxybenzoic acid and its substituted phenylazoderivatives have been prepared, together with some mixed-metal (Co, Cu or Ni, Cu) complexes of itsm-nitro,m-carboxy andm-hydroxyarylazo derivatives. The stereochemistries and the modes of bonding of the complexes were elucidated by spectral and magnetic susceptibility measurements.Abstracted from her Ph.D. thesis.     

Ion-Pair Formation in Pharmaceutical Analysis. Conductimetric Determination of Promazine, Chlorpromazine, Promethazine, Imipramine and Ciprofloxacin Hydrochlorides in Pure Form, Drug Formulations and Urine

 Potassium ferricyanide and sodium tetraphenylborate were used as titrants for the conductimetric determination of promazine HCl, chlorpromazine HCl, promethazine HCl, imipramine HCl and ciprofloxacin HCl through ion-associate complex formation. The molar combining ratio, effects of dilution of titrant, temperature and solvent were studied. The accuracy of the method is indicated by excellent recovery (99.50–99.96%). The sensitivity of the proposed method is discussed and the results are compared with the pharmacopoeial or the official methods. The suggested method has been applied for the analysis of the mentioned compounds in their pharmaceutical formulations and urine. Received March 1, 1998. Revision May 31, 1999.     

Effect of gamma-rays on the formation of color centers in copper-containing lead borate glasses

Absorption bands in the range of 350–950 nm, induced in copper-containing lead borate glasses by -rays were identified and characterized. The effect of irradiation dose, copper oxide and lead oxide contents on the intensity and position of the induced absorption bands were also considered. Several induced absorption bands were observed. At least two bands in the ranges of 740–780 and 850–870 nm could be identified. They are suggested to be associated with induced Cu⁽²⁺⁾ ions. The band in the 800–830 nm (1.6 eV) range is ascribed to the Pb⁽³⁺⁾ ion, whereas others in the ranges of 600–630 and 650–730 nm are associated with the intrinsic defects formed in the base glass.     

Synthesis of some dibenzodiazepinone derivatives as potent and m2-selective antimuscarinic compounds

Two series of 5-[[4-[4-(dialkylamino)butyl]-l-cyclohexyl]acetyl], and 5-[(dialkylamino)acyl]-10,11-dihydro-5H- dibenzo[b,e][1,4]diazepin-11-ones were synthesized as potential m2-selective ligands 1,2. Their affinity and selectivity for the muscarinic cholinergic receptor m-AChR subtypes were determined. Replacing a nitrogen with CH in the piperidine ring of 5-[[4-[4-(dialkylamino)butyl]-l-piperidinyl]acetyl]-10,11-dihydro-5H-dibenzo-[b,e][1,4]diazepin-11-ones 3 significantly altered the affinity and selectivity to the muscarinic receptor subtypes.