Hydrothermal synthesis and structural characterization of two unprecedented photoluminescent coordination polymers constructed from Cd salt and mixed ligand

Two new Cd-containing coordination polymers {Cd₂(succ)₂(1,10′-phen)₂} _n (1) and {Cd(glut)(1,10′-phen)(H₂O)} _n (2) are described. Complex 1 exhibits an interesting 2-D structure in which the binuclear Cd centers are linked by succinate anions. Complex 2 possesses an interesting 1-D chain-like structure. The IR and TG properties of the two compounds are studied. Furthermore, these two complexes exhibit photoluminescence.     

MECHANISM OF THE REACTION OF SOME STABLE HEMIMERCAPTALS WITH Secondary-AMINES: EVIDENCE AGAINST THE INTERMEDIACY OF A METHYLENESULFONIUM ION

Abstract

The reaction of the arenethiols 4a-b with formaldehyde and the sec-amines 5a-c gave the aminomethyl aryl sulfides 6a-d. The reaction of the hemimercaptals 3a-b with 5a in methanol gave 6a-b in high yield. In acetonitrile reaction media, 6b was obtained by the reaction of 3b with 5a which suggested that 7b was not an intermediate in the formation of 6b in methanolic media. The absence of 7b in methanolic media suggests that the methylenesulfonium ion 8b is not an reaction intermediate. The formation of 7b was observed in the reaction of 3b with methanol when catalyzed by the Lewis acid tetrafluoroboric acid diethyl ether complex. The experimental observations are best explained by a mechanism whereby 3a-b are in rapid equilibrium with 4a-b under the basic reaction conditions. Rapid reaction of the liberated formaldehyde with 5a leads to the normal Mannich reaction pathway. Consistent with this mechanism, the reaction of a mixture of 3a-b and 12 with 5a gave both 6a-b and 13.     

Three lanthanide complexes with mixed salicylate and 1,10-phenanthroline: syntheses,crystal structures,and luminescent/magnetic properties

Three new lanthanide complexes incorporating salicylate (HSA or SA) and 1,10-phenanthroline (phen), Ln₃(HSA)₅(SA)₂(phen)₃ [Ln = Ho (1) and Er (2)], and Sm₂(HSA)₂(SA)₂(phen)₃ (3), have been synthesized. X-ray structural analysis reveals that 1 and 2 are isostructural with a trinuclear pattern, and 3 exhibits a binuclear structure. Comparison of the structural differences between 1/2 and 3 suggests that the identity of metal plays an important role in construction of such complexes. The magnetic properties of 1 are discussed. Moreover, 2 and 3 are both photoluminescent materials, and their emission properties are closely related to their corresponding Ln^III centers.     

Drag on an ellipsoid particle in free-molecular plasma flow

Based on the analysis of molecular gas dynamics, the drag and moment acting on an ellipsoid particle of revolutionX ²/a ²+Y ²/a ²+Z ²/c ²=1, as an example of nonspherical particles, are studied under the condition of free-molecular plasma flow with thin plasma sheaths. A nonzero moment which causes nonspherical particle self-oscillation and self-rotation around its own axis in the plasma flow—similar to the pitching moment in aerodynamics—is discovered for the first time. When the ratio of axis lengthc/a is unity, the moment is zero and the drag formula are reduced to the well-known results of spherical particles. The effects of the particle-plasma relative velocity, the plasma temperature, and the particle materials on the drag and moment are also investigated.     

Azo compounds and Schiff 's bases derived from 5-(4-pyridyl)-2-amino-1,3,4-thiadiazole: synthesis,mesomorphic properties and structural study by semi-empirical calculations

The synthesis and liquid crystalline properties of new Schiff 's bases (series 3a-f) and azo compounds (4a-f) incorporating pyridine and 1,3,4-thiadiazole rings are reported. The first homologues in the series of Schiff's bases (3a-c) show a monotropic mesophase and the homologues 3d-f display an enantiotropic SmA phase. The only azo compounds to exhibit liquid crystalline properties are the homologues 4e, f which show a monotropic nematic phase. These series are compared with Schiff's bases and azo compounds analogues (series 5 and 6), previously reported by us and an AM1 study of the structure/mesomorphic property relationship is described.     

CATALYSE INTRAMOLECULAIRE DE L'AMINOLYSE DES HETEROCYCLES PHOSPHORES DERIVES DES α AMINOAMIDES. II: ETUDE DE LA CYCLISATION DES PHOSPHORDIAMIDES INCORPORANT UN RESIDU DE β AMINOACIDE,REACTIVITE VIS A VIS DE NUCLEOPHILES DES HETEROCYCLES FORMES

Abstract

Derivatives of β aminoacids in form of esters 1 or nitrile 4 (table I) undergo in an alcohol-ate/alcohol medium a rearrangement (Fig. 2), with formation of a β peptide link, resulting in the formation of esters 6 (table II). According to the experimental conditions the six membered ring heterocycles 5 are detected or isolated. They are also synthetized by cyclisation of acids 2 or hydrazide 3 (Fig. 5). While phosphorus easily reacts with alcohols and water, leading respectively to esters 6 and acids 9 (Fig. 7), it remains unaffected by amines. These results are discussed in term of mechanisms of the phosphorylation. The applications for β peptide synthesis and the participation of the p amide group in phosphorylation are limited.     

Base-mediated one-pot synthesis of 3,4,5,6-tetrahydro-4-substituted benzo[h]quinazoline-2(1H)-thione derivatives and evaluation of their antioxidant activity

One-pot three-component Beginelli-like reactions of a ketone 1, an aryl aldehyde 2, and thiourea 3 in the presence of sodium hydroxide are described. In this reaction, 3,4,5,6-tertrahydro-4-substituted quinazoline-2(1H)-thione derivatives 4a–h were obtained in good yields (73–85%). The compound 4a has been characterized by single crystal X-ray analysis. All the synthesized compounds 4a–h and 5a–b were screened for their in vitro antioxidant activity. Compounds 4c, 4e, and 4h have exhibited an excellent than the standard ascorbic acid. Compounds 4d, 4f, and 4g have also shown good activity. Remaining compounds show moderate antioxidant activity.     

Chemie der Pleuromutiline,VII. Basisch induzierte transanulare 1,4-Hydridverschiebung in 8-substituierten Pleuromutilinderivaten

The syntheses of the pleuromutilin derivatives12 and16 are described. Both compounds on treatment with base rearrange to the isomeric ketol13. The results of the deuteration experiment as well as the kinetic measurements are in agreement with the hypothesis of an intramolecular 1,4-hydride shift.

Die 3-Hydroxyverbindung4 ist nicht isolierbar.     

PHOSPHORORGANISCHE VERBINDUNGEN 1171, EINE NEUE METHODE ZUM NACHWEIS DER FUNKTIONELLEN GRUPPEN: OH,NH2 UND SH DURCH AUSLOSUNG VON FLUORESZENZ

Abstract

Covalently with a fluorescence support linked nitroarylester groups quench the fluorescence. The substitution of the fragment with the quenching group by an other functional group initiates fluorescence. If this substitution reaction is chemoselective, a reagent for the selective detection of a special functional group is available.

The non fluorescent compounds 1a and 1b are OH-(resp. F^(-)) selective; the compounds 5 and 7 are NH-selective and the compounds 8 and 9 are SH-selective. Dansyl-nitroimidazolide 7a discriminates between neutral and basic α-amino acids.     

IR spectroscopic study of ion-molecular interactions in the methanesulfonic acid—N,N-dimethylformamide system

Complex formation in the methanesulfonic acid (MSA)-DMF system was studied by Multiple Attenuated Total Reflectance (MATR) IR spectroscopy at 30°C within the composition range from neat MSA up to neat DMF. Depending on the ratio of components, two types of complexes with a strong quasi-symmetrical H bond (1 and2) are formed. The uncharged complex1 is a quasi-ion pair with the (O…H…O) bridge. Complex2 is formed by a protonated DMF molecule and the (A…H…A)⁻ anion bound as an ion pair. It is established that complexes1 are solvated by DMF molecules in an excess of a base. Solvation or2 in an excess of an acid corresponds to a change from contact to contact-separated ion pairs. Continuous absorption spectra of charged and uncharged complexes1 and2 were obtained. The schemes of acid-base interactions in the MSA-DMF and HCl-DMF systems were compared. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2484–2489, December, 1998.     

Vergleichende Reaktivitätsuntersuchungen am neuen Codimeren aus Malonitril und Cyanessigester an Carbonylverbindungen

The reactivity of 3-amino-2,4-dicyano-methyl-(1d) and-ethyl-crotonate (1e), resp., a new type of codimer from malononitrile and cyanoacetate, was investigated. Condensation reactions with aromatic aldehydes (2a-g), with heterocyclic aldehydes (2j-l), nitrosobenzenes (3a-c) ando-hydroxybenz-and-naphtaldehydes (4a-f), resp., are described, the differences in reactivity, compared with dimer malononitrile and dimeric forms of cyanoacetate (1a-c) are negligible. Condensation compounds of1a with cycloalkanones (5a-c) are able to cyclise with sulfur to cycloalkanonothieno-pyridines (6a-b), while the cycloalkano-derivatives of1d gave no ring closure.

Herrn Prof. Dr.O. E. Polansky zum 60. Geburtstag in Erinnerung an gemeinsame Tätigkeiten auf dem Gebiet der Nitrilchemie gewidmet.     

Synthesis of Vinyl Sulfones from Aryl Methyl Ketones Under Sonochemical Conditions and Formation of Allyl Sulfones

An efficient synthesis of vinyl sulfones 3a-o from aryl methyl ketones 2 bearing an electron withdrawing group and the phosphonic ester 1 under sonochemical conditions is reported. These compounds are generally obtained as an E/Z mixture. Formation of the allyl sulfones 4 is also observed.     

Practical Synthesis of Functionalized 2‐Thioxoimidazolidine Derivatives

High‐yielding syntheses of an unpublished series of 2‐thioxo‐imidazolidin‐4‐ones 6 bearing an N‐ethoxycarbonyl and amidyl moieties an N₁ and C₅, respectively, are reported. These derivatives were obtained by intramolecular cyclization of 3‐ethylhydrazinoacetate 3,4‐dihydro maleimides 4 in the presence of ethyl or phenylisothiocyanate 2 under neutral conditions.     

CONVENIENT SYNTHETIC METHODS FOR THE PREPARATION OF N-FLUOROALKYLHYDROXAMIC ACIDS

ABSTRACT

Polyhydroxamate chelators containing fluoro substituents are of interest as potential extractants for actinides in separations involving supercritical carbon dioxide. In this context, we have developed three new reagents 1, 2, and 3, that allow the efficient incorporation of an N-fluoroalkyl hydroxamate moiety onto a variety of substrates using acylation, alkylation, and Michael addition strategies.     

Structure of D-Fructosamine Hydrochloride and D-Fructosamine Hydroacetate

D-Fructosamine derivatives are key intermediates of the early Maillard reaction and have been a subject of numerous studies in food and health sciences due to their implication in the nutritional and organoleptic quality of foods, as well as to complications in diabetes and renal disease. We report the crystal structure analyses of 1-deoxy-β -D-fructopyranos-1-ylamine hydrochloride (1) and -hydroacetate (2) salts. The carbohydrate rings adopt the normal ²C₅ pyranose chair conformation in 1 and 2. Bond lengths and valence angles in 1 and 2 compare well with the average values from related pyranose structures. There are two conformationally nonequivalent molecules in the asymmetric unit in 1. All hydroxyl and ring oxygen atoms, ammonium groups, and chloride ions in 1 are involved in an extensive three-dimensional hydrogen bonding network. The hydrogen bonding network in 2 is formed by one type of infinite chain with attached antidromic cycles.     

The Effect of Trifluoroethoxy Groups on the Structures of Eight-Membered Ring-Containing Cyclic Phosphites 1

New phosphites 1–4 were synthesized from phosphorus trichloride and an appropriate diphenol followed by the addition of trifluoroethanol in the presence of triethylamine. These phosphites are to serve as precursors in the syntheses of biorelated hypervalent phosphoranes. ¹H, ¹⁹F, and ³¹P NMR spectra were recorded. X-ray analysis of 3 and 4 revealed that the sulfur-containing eight-membered ring was in a syn conformation that a allowed a sulfur donor interaction to the phosphorus atom, whereas for phosphite 2, the eight membered sulfonyl containing ring was in an anti conformation that did not allow a donor interaction to phosphorus from the oxygen atom of the sulfonyl group. Structural comparisons are made with related cyclic phosphites and phosphates having donor atoms in eight-membered rings.     

New and Practical Synthesis of Montelukast Sodium,an Antiasthmatic Drug

Abstract

A new and practical synthesis of montelukast sodium, an antiasthmatic drug, is described. The key steps are the synthesis of nitrile derivative 4 by chiral reduction of keto ester 9 using (?)-DIP-Cl, synthesis of vinylquinoline framework 16 by Wittig reaction, and Heck coupling of nitrile 4 with vinylquinoline 16. The method is operationally simple and suitable for the industrial production of the drug substance.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

SELECTIVE ALKYLATION/ACYLATION OF DI- OR TRIANIONS: EXPEDITIOUS DERIVATIZATION OF ENDOTHELIN ANTAGONISTS[1]

ABSTRACT

Sitaxsentan sodium (1, TBC11251Na) is an ET_A selective endothelin antagonist under clinical development for pulmonary arterial hypertension and congestive heart failure. Second generation compounds, as exemplified by TBC2576 (2) are currently under development in our laboratories. To rapidly access analogs of 1 and 2, a route was developed for the selective alkylation or acylation of the corresponding di- or trianions derived from these two highly functionalized compounds. We report here on this straightforward, yet effective, procedure consisting of treating the di- or trianions with an excess amount of electrophiles, followed by a rapid quench. In this manner, selective alkylation or acylation of 1 and 2 was achieved with satisfactory yields.     

Delayed lanthanide luminescent Tb(III) complexes formed from lower rim amide functionalised calix[4]arenes

The synthesis and the photophysical studies of a new generation of time resolved luminescent systems based on calix[4]arenes alkylated at the lower rim, capable of hosting lanthanide (III) ions such as terbium and sensitising its emission, are described. Two series of ligands were designed to provide an ideal cavity to host terbium (Tb(III)) and were synthesised in high yields following two novel approaches. The tetra-alkylation, which was achieved in one step using with piperidino- and morpholino-acetamide pendant arms, provides eight donor atoms forming a binding ‘pocket’ at an ideal distance from the metal core to favour the sensitisation via the antenna effect. Of the two ligand series developed, compounds 3 and 4 possess a short spacer between the calix and the amide receptor site. The second series of ligands 6–7, designed with longer pendant amide arms, was synthesised from 2 in two steps through the ester analogue 5. The crystal structure of 3 (and 6 as shown in Supporting Information, available online) is presented. The synthesis and the photophysical studies of the four resulting complexes 3.Tb, 4.Tb, 6.Tb and 7.Tb are described in detail and in each case, successful sensitisation of the terbium emission occurred upon excitation of the phenolic scaffold of the calixarene.     

Cation Selectivity of a Folded Ditopic Crown Receptor

The synthesis and cation binding properties of a folded ditopic crown receptor, 3, are described. Intramolecular hydrogen-bonding interactions preorganize ditopic crown 3 into a helical conformation that positions the crown moieties in a manner that favors the formation of an intramolecular sandwich cation complex. Alkali-metal picrate extraction studies demonstrate that ditopic crown 3 exhibits a significantly different cation selectivity than mono-crown congener 2. A crystal structure of 3?2KClO⁴ indicates that two molecules of the complex are assembled into a molecular square in the solid state.