Synthesis of Heterocyclic Compounds from Metallated Unsaturated Compounds and Isothiocyanates. (Review)

Novel syntheses of heterocyclic compounds resulting from reactions of metallated acetylenes, allenes, and conjugated dienes with isothiocyanates and from reactions of the latter with strong bases are reviewed.     

N,N′-二(芳磺酰)亚磺酰胺-S-(2-苯并咪唑基)类化合物的合成

本文报道了新化合物N,N＇—二(芳磺酰)亚磺酰胺—S—(2—苯并咪唑基)钠(a～e)以及N,N＇—二(芳磺酰)亚磺酰胺—S—(2—苯并咪唑基)(f～i)的合成。通过在感光乳剂中的应用,我们发现a,b和c具有超增感作用,它们分别使卤化银乳剂的感光度提高62％,22％和45％。 钠—N—氯芳磺酰亚胺化合物既是一类精细化工产品,又是一类重要的反应中间体。由它们     

Oxidation of Heterocyclic Compounds by Permanganate Anion. (Review)

Data on the oxidative transformations of heterocyclic compounds with permanganate anion are reviewed     

N-Cyanoimines in the Synthesis of Heterocyclic Compounds. (Review)

Methods for the synthesis of N-cyanoimines in the period between 1959 and 2003 and their chemical properties are examined. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 963–973, July, 2005.     

Noncovalently-Bound Cyclodextrin Dimers and Related Compounds. (Review)

In the review noncovalently-bound cyclodextrin (CD) dimers, i. e., CD host-guest 2:1 complexes as well as CD self-assembled inclusion oligomers, are briefly characterized, showing methods of their investigations; the properties and possible applications of these species are also described. __________ Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1603–1624, November, 2005.     

Oxygen-containing Heterocyclic Compounds from 1,5-Diketones. (Review)

Literature and characteristic experimental data correlated in the review concern the intramolecular cyclization by various means of substituted 1,5-diketones of the acyclic, semi-, and bicyclic series, proceeding to the formation of oxygen-containing heterocycles, such as pyrans, pyrylium salts, di- and tetrahydrofurans, and their condensed analogs, aroylfurans etc.     

Catalytic Synthesis of Some Sulfur-containing Heterocyclic Compounds. (Review)

Researches on the synthesis of sulfur-containing heterocyclic compounds at the G. K. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, are reviewed. They include the synthesis of thiolane by the recyclization of THF in hydrogen sulfide; the synthesis thiacycloalkanes by the hydrogenation of thiophenes; the synthesis of 4-methylthiazole by the reaction of SO₂ with methylisopropylideneamine; the synthesis of thiophenes by the heterocyclization of aliphatic compounds of sulfur and dehydrogenation of thiacycloalkanes; the synthesis of thiolane 1,1-dioxide by the hydrogenation of 2- and 3-thiolene 1,1-dioxides and 3-alkoxythiolane 1,1-dioxides; the synthesis of sulfoxides by the oxidation of thiacycloalkanes with atmospheric oxygen.     

Alkynyl- and Alkenyl(phenyl)iodonium Compounds. New Synthetic Methods (86)

Compounds with highly coordinated, polyvalent main-group elements represent an interesting alternative to the many well-known transition-metal complexes. Among the oldest and best known stable examples of such organic molecules are the iodine(III) compounds. Diaryliodonium species, Ar₂IX, for example, have been known for over a hundred years and play an important role in lithography. Likewise, acetylenes and olefins are among the oldest, most important, and most valuable compounds in chemistry. Besides simple hydrocarbon alkenes and alkynes, numerous functionalized derivatives are also known and widely employed in organic chemistry. Despite the ubiquity and prominance of both I^III species and olefins and acetylenes, the combination of these two types of functional groups in a single molecular unit, namely compounds with polyvalent iodine and at least one alkyne or olefin residue, was unknown until recently. The successful preparations of simple alkynyl- and alkenyl-(phenyl)iodonium species during the 1980s has resulted in a renaissance in both acetylene and I^III chemistry. These alkynyliodonium compounds readily undergo nucleophilic substitution on the alkyne moiety (S_N-A reactions) which are difficult with other substrates. The application of a wide variety of nucleophiles in this reaction resulted in diverse functionalized alkynes including previously unknown acetylenic carboxylates, sulfonates, and phosphates. These are excellent substrates for cycloaddition reactions as well as numerous other interesting chemical transformations.     

Aluminum(I) and Gallium(I) Compounds: Syntheses,Structures, and Reactions

By the end of the last century there were already the first indications of the possible existence of Al¹ halides. However, it was only through the pioneering works of W. Klemm, who would have celebrated his 100th birthday on January 6, 1996, that detailed spectroscopic investigations became possible. Since the end of the 1970s the reactivity of AlX and GaX species in solid noble gases has been confirmed by numerous examples. In recent years formally monovalent Al and Ga species have been successfully synthesized on a preparative scale. In addition to the first halides, organometallic compounds with metal–metal bonds have been isolated and investigated with regard to their chemical properties. The fundamental importance of such species has been documented in this journal among others in the form of two highlight articles in which experimental and theoretical aspects have been examined with examples, and parallels and differences with respect to boron chemistry have been illustrated. This review is intended to give an account of the chronological development of this research area over the last few years, but an attempt is also made to categorize the experimental results achieved not only with respect to structure, thermodynamics, and reactivity, but also with the aid of quantum chemical calculations and by comparative considerations.     

Synthesis, Chemistry, and Applications of Heterocyclic Cage Compounds (V)

The synthesis and chemistry of polycyclic of cage compounds have attracted considerable attention in recent years. The vast majority of the work reported in this area has dealt with carbocylic cage compounds. On the other hand, the synthesis and chemistry of heterocyclic cage compounds have received less attention. Recently, we envisioned that studies on the synthesis and chemistry of heterocyclic cage compounds can greatly expand the scopes and utilities of cage compounds.1 As part of a program that involves the synthesis, chemistry, and application of heterocyclic cage compounds, we report here the synthesis of new thia-oxa-cage compounds and the chemical nature of these thia-cages.     

Dilithium Hexaorganostannate(IV) Compounds

Hypercoordination of main‐group elements such as the heavier Group 14 elements (silicon, germanium, tin, and lead) usually requires strong electron‐withdrawing ligands and/or donating groups. Herein, we present the synthesis and characterization of two hexaaryltin(IV) dianions in form of their dilithium salts [Li₂(thf)₂{Sn(2‐py^Me)₆}] (py^Me=C₅H₃N‐5‐Me) ( 2 ) and [Li₂{Sn(2‐py^OtBu)₆}] (py^OtBu=C₅H₃N‐6‐OtBu) ( 3 ). Both complexes are stable in the solid state and solution under inert conditions. Theoretical investigations of compound 2 reveal a significant valence 5s‐orbital contribution of the tin atom forming six strongly polarized tin–carbon bonds.     

Flavanone Glycosides,Triterpenes, Volatile Compounds and Antimicrobial Activity of Miconia minutiflora (Bonpl.) DC. (Melastomataceae)

Chemical composition of the essential oils and extracts and the antimicrobial activity of Miconia minutiflora were investigated. The flavanone glycosides, pinocembroside and pinocembrin-7-O-[4″,6″-HHDP]-β-D-glucose, were identified, along with other compounds that belong mainly to the triterpene class, besides the phenolics, gallic acid and methyl gallate. Sesquiterpenes and monoterpenes were the major compounds identified from the essential oils. Screening for antimicrobial activity from the methanolic extract of the leaves showed that the MIC and MMC values against the tested microorganisms ranged from 0.625 to 5 mg·mL⁻¹ and that the extract was active against microorganisms, Staphyloccocus aureus, Escherichia coli, and Bacillus cereus.     

Divalent Silicon(0) Compounds

Bridge of Si's : Quantum‐chemical calculations suggest that the bonding situation in the recently synthesized “trisilaallene” is better described in terms of donor–acceptor interactions between two silylene ligands L and a naked silicon atom Si, which carries two lone‐pair orbitals, yielding the silylone SiL₂. Further silylones SiL₂ with different donor ligands Si have also been calculated, which might be possible to synthesize.

     

Compounds of hypercoordinated gold(i)

A binuclear organic derivative of gold(i) with diphenylmethane CH₂(C₆H₄)₂(AuPPh₃)₂ has been prepared by the reaction of 2,2-dilithiumdiphenylmethane with ClAuPPh₃. X-ray analysis of this compound revealed a transoid conformation of the molecule with agostic bonds between the gold atoms and methylene hydrogens. The complex was characterized by IR,¹H and³¹P NMR, and mass spectral data.For Report 1 seeRuss. Chem. Bull., 1994,43, 681.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1125–1130, June, 1994.This work was performed with partial financial support from the International Science Foundation (Project No. MDV 000).     

Solvatochromism of Heteroaromatic Compounds: XX. 4(5)-Nitroimidazole

4(5)-Nitroimidazole in solution is stabilized as the 5-nitro isomer due to formation of hydrogen bond with an aprotic protophilic solvent. Amphiprotic medium favors displacement of the tautomeric equilibrium toward the 4-nitro isomer via formation of a solvate complex where 4-nitroimidazole acts as hydrogen bond acceptor. The observed specific solvatochromic effect in the UV spectrum of 4-nitroimidazole and related heterocyclic nitro compounds is determined by the electronic configuration of the excited ,^*-state.     

Existence of Molecular Palladium(VI) Compounds: Palladium Hexafluoride.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.     

New Compounds of quinquevalent Molybdenum. Ethylenediammonium oxopentachloro molybdate(V)

Ethylene diammonium oxopentachloro molybdate(V) enH₂ [MoOCl₅] (where en = ethylene diammine) has been isolated in pure state and has been characterised by chemical analysis, oxidation state determination, magnetic measurement, spectroscopic investigations and conductivity measurements. Its reactions have been studied in solution and solid state.