Luteone,a twenty three carbon terpenoid from the dorid nudi branch Cadlina luteomarginata

The structure of luteone ($\text{1}$), a twenty three carbon terpenoid, has been solved by performing a single crystal x-ray analysis on a 3,4-dinitrophenylhydrazone derivative.     

New synthetic routes to cationic rhenium tricarbonyl bipyridine complexes with labile ligands

Triflate abstraction from the complex [Re(OTf)(CO)(3)(bipy)] (1) using the salt NaBAr'(4) (Ar' = 3,5-bis(trifluoromethyl)phenyl) in dichloromethane solution in the presence of L = PPh(3), NCMe, NCPh, imines, ketones, Et(2)O, THF, MeOH, and MeI affords cationic complexes [Re(L)(CO)(3)(bipy)](+) as their BAr'(4)(-) salts. The new complexes have been characterized spectroscopically and, for [Re(eta(1)-O=C(Me)R)(CO)(3)(bipy)]BAr'(4) (R = CH(3), 6a; R = Ph, 6b), and [Re(THF)(CO)(3)(bipy)]BAr'(4) (9), also by single-crystal X-ray diffraction. Compared with conventional methodologies, the route reported here allows the coordination of a broader range of weakly coordinating ligands and requires considerably milder conditions. On the other hand, the reactions of lithium acetylides with [Re(THF)(CO)(3)(bipy)]BAr'(4) (9) can be used for the high-yield syntheses of rhenium alkynyls [Re(Ctbd1;CR)(CO)(3)(bipy)] (R = Ph, 12; R = SiMe(3), 13). Complex 9 was found to catalyze the aziridination of benzylideneaniline with ethyl diazoacetate.     

The signal-to-noise ratio as the measure for the quantification of lysophospholipids by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry

The subject of this report is the determination of lysophospholipids; lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylserine and lysophosphatidic acid, by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS). The mean signal-to-noise ratio (S/N) was used for the first time as a measure of lysophospholipid concentration. Two different sample preparation procedures were applied, the 'standard' procedure and the 'premix' in order to check to what extent these methods influence the results of the lysophospholipid quantification. Results can be summarised as follows: (a) All classes of lysophospholipids can be easily and sensitively analysed by MALDI-TOF MS. The smallest detectable amount of lysophospholipids was 0.09 pmol on the sample plate. That is about two orders of magnitude lower than the amount detectable by standard chromatographic methods. (b) The mean S/N of all peaks detected in the positive ion mass spectra can be used as a measure of the lysophospholipid concentration. Whereas the S/N for neutral lysophospholipids correlated with the applied concentrations only when the samples were analysed as 'premix', the sample preparation and application procedure did not influence the quantification of acidic lysophospholipids. The standard deviations were not higher than 10% of the mean value. (c) All spectra were additionally analysed in the presence of CsCl. The addition of caesium ions makes the peak identification unambiguous in phospholipid mixtures, but the Cs adducts of lysophospholipids do not properly reflect their concentration and, therefore, they were not useful for quantification. (d) The applicability of the method was demonstrated on the organic extract of human neutrophils.     

Nitropyrazoles

The double Vilsmeier formylation of theC-methyl group in pyrazole derivatives has been shown to occur when a nitro-group is in the adjacent position of the ring. A method for the synthesis ofC-(diformylmethyl)nitropyrazoles based on this reaction has been developed.For the previous communication, see Ref. 1; for Part 2, see Ref.2 Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1273–1276, July, 1993.     

Para-ordered polybenzimidazole

A series of novel AB monomers such as 2-[p-carboxyphenyl]-5,6-diaminobenzimidazole hydrochloride have been synthesized. In addition, a new aromatic monomer, 1,3-diamino-4,6-bis(p-toluenesulfonamido)benzene has been prepared in high purity and substituted for 1,2,4,5-tetraaminobenzene in a polymerization with terephthalic acid. Homopolymerization of the AB monomers, and polycondensation of monomer with terephthalic acid in polyphosphoric acid, produced the rod-like para-oriented polymer, poly[1,7-dihydrobenzo(1,2-d: 4,5-d)diimidazole-2,6-diyl-1,4-phenylene]. The yellow polymer was completely soluble in methanesulfonic acid (MSA) and PPA, exhibiting intrinsic viscosities as high as 5 dl/g in MSA, and a blue opalescence in solution. Polymerization at temperatures above 225°C caused crystallization and subsequent precipitation to occur. Polymer thus obtained was completely insoluble in MSA and possessed a high degree of crystallinity as demonstrated by x-ray analysis.     

Synthesis and structure of Ca(18)Li(5)In(25.07): a novel intergrowth of Li-centered in(12) icosahedral clusters and electron-precise Zintl layers

A new ternary polar intermetallic, Ca(18)Li(5)In(25.07), was obtained from high-temperature reactions of the elements in welded Nb tubes. Its crystal structure, established by single-crystal X-ray diffraction, was found to crystallize in the orthorhombic space group Cmmm (No. 65). Unit cell parameters are a = 9.9151(6) A, b = 26.432(2) A, and c = 10.2116(6) A; Z = 2. The structure of Ca(18)Li(5)In(25.07) features two distinct types of indium anionic layers. An "electron-deficient" layer is made up of Li-centered In(12) icosahedra that are interconnected by bridging planar In(4) units and In atoms. A second In(3)(5-) layer is an electron-precise Zintl layer formed by fused four-, five-, and six-membered rings of three- and four-bonded indium atoms. The two distinct layers are alternately stacked and linked into a complex three-dimensional network. Vacancies are observed to occur only at the In(12) icosahedral and the bridging indium units within the "electron-deficient" layers. Magnetic property measurements indicate that Ca(18)Li(5)In(25.07) exhibits temperature-independent paramagnetism consistent with metallic behavior. Band structure calculations were performed to elucidate the role of defects and vacancies in the electronic structure of the electron-deficient "metallic" Zintl phase.     

Mass spectral fragmentation patterns of heterocycles. VI. Carbazole and 1,8-dideuteriocarbazole

The mass spectral fragmentation of carbazole was reinvestigated using metastable ion studies, exact mass measurements and 1,8-dideuteriocarbazole. 1,8-Dideuteriocarbazole was prepared by successive metalations and deuterations of carbazole. The ¹H- and ¹³C-nmr spectra of 1,8-dideuteriocarbazole confirmed earlier assignments for carbazole.