Nitroazines. Methods of synthesis (review)

Published data on methods for the production of six-membered nitrogen heterocycles containing a nitrogroup are classified systematically.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 147–165, February, 1985.     

Methods for the synthesis of cinnolines (review)

This review analyses the principal approaches to the synthesis of the cinnoline nucleus, used as synthetic precursors of arenediazonium salts, arylhydrazones, and arylhydrazines, and also reductive methods for the synthesis of polycondensed derivatives of cinnoline. The mechanisms of the transformations and the possibilities and limitations of the various methods are discussed. Special attention is paid to methods based on the cyclization of derivatives of arenediazonium salts, which have been developed substantially in recent years. In memory of A. A. Potekhin __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 643–667, May, 2008.     

Methods for the synthesis of haloimidazoles (review)

Published information on methods for the synthesis of haloimidazoles is summarized and classified.     

Di(propargyl)nitramine: synthesis and reactivity

An improved synthesis of (propargyl)nitramine and its pioneering conversion to di(propargyl)nitramine involve the alkylation of NH nitramines with propargyl halides or tosylate as the key steps. The standard (p° = 0.1 MPa) molar enthalpy of formation at 298.15 K for di(propargyl)nitramine was determined from the experimental standard molar energy of combustion in oxygen, measured by static bomb combustion calorimetry. Propargyl nitramines are suitable substrates for 1,3-dipolar cycloaddition reactions with azides, nitrile oxides and diazo compounds.     

Methods for the synthesis of benzofuran derivatives (review)

Data published in the last 15 years on methods for the construction of the benzofuran ring are reviewed. The mechanisms of the reactions and their use in the synthesis of biologically active substances are discussed. North-Osetinsk State University, Vladikavkaz. Pyatigorsk State Pharmaceutical Academy, Pyatigorsk. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1443–1458, November, 1997.     

Methods for the synthesis of 3-nitropyridines (review)

The review includes the published data on methods for the synthesis of compounds that contain the 3-nitropyridine skeleton from acyclic synthones and via transformation of other heterocyclic rings.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 867–896, July, 1991.     

Updates on synthesis and biological activities of 1,3,4-oxadiazole: A review

The new era of heterocyclic moieties which are developed in the decades plays a very important role in the treatment of various diseases. Among them are 1,3,4-oxadiazoles, a heterocyclic five-membered ring which plays an vital role in the development of newer medicinal compounds for treating various biological activities, such as proliferation of cells, tuberculosis, allergy, viral diseases, etc. The present review will summarize the various synthetic approaches which will be correlated with the biological activities so that the information in future may be used by many researches to give a path breaking lead in the field of medicinal chemistry.     

A Facile [hydroxy(tosyloxy)iodo]benzene Mediated Synthesis of Symmetrical Triazolo-[3,4-b]-1,3,4-Thiadiazines

Synthesis of the title compounds has been accomplished by a one-pot procedure involving the reaction of 3-substituted-4-amino-5-mercapto-1,2,4-triazoles and a variety of heterocyclic ketones in the presence of [hydroxy(tosyloxy)iodo]benzene.     

Methods for the synthesis of 2-aminothiophenes and their reactions (review)

2-Aminothiophenes are readily formed as a result of various cyclization reactions. The method of preparation of derivatives of 2-aminothiophene-3-carboxylic acids and 2-amino-3-acylthiophenes from carbonyl compounds, nitriles that have an active methylene group, and sulfur is particularly simple and rich in possibilities. The aminothiophenes can be converted to other thiophene derivatives and used primarily for the preparation of condensed thiophenes such as thionaphthenes, thienopyrroles, thienothiazoles, thienoisothiazoles, thienopyrimidines, thienopyridines, and thienodiazepines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1299–1315, October, 1976.     

Fluorotris(trifluoromethylsulfonyl)methane: synthesis, characterization and reactivity

The hitherto elusive title compound was synthesized and characterized with the aim to study its potential as a carbon-based (“CF-type”) electrophilic fluorination reagent. A detailed discussion of its structure, properties and reactivity is based on experimental studies as well as on molecular modeling.     

Superior reactivity of thiosemicarbazides in the synthesis of 2-amino-1,3,4-oxadiazoles

A facile and general protocol for the preparation of 2-amino-1,3,4-oxadiazoles is reported. This method relies on a tosyl chloride/pyridine-mediated cyclization of a thiosemicarbazide, which is readily prepared by acylation of a given hydrazide with the appropriate isothiocyanate. Cyclization of the thiosemicarbazide consistently outperforms the analogous semicarbazide cyclization under these conditions, for 18 distinct examples. Utilizing this protocol, we have prepared 5-alkyl- and 5-aryl-2-amino-1,3,4-oxadiazoles in 78-99% yield.     

Methods for the synthesis of azoles containing indole substituents (review)

A systematic review is given for advances in the synthesis of various azoles (imidazoles, oxazoles, thiazoles, pyrazoles, oxadiazoles, and triazoles) containing indole fragments. A significant number of biologically active compounds have been found among these bisheterocyclic compounds.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 147–172, February, 1986.     

Ethynylindoles and their derivatives. Methods of synthesis and chemical transformations (review)

The review contains data on methods for the production of ethynylindoles and their derivatives. The whole range of transformations of these compounds is examined in detail. It is demonstrated that indoles containing highly unsaturated groups are interesting not only as subjects for fundamental researches but can also be used successfully for the solution of various practical tasks.     

Synthesis and reactivity of 1,3,2-dithiazoles (review)

Data on the synthesis and reactions of 1,3,2-dithiazoles over the last 30 years are reviewed and classified.     

2-(4-Biphenylyl)-1,3,4-oxadiazoles: synthesis and mesogenic studies

A series of 2-(4-biphenylyl)-1,3,4-oxadiazoles bearing alkyl or alkoxy substituents at the 4? position, and a hydrogen, or alkyl substituent (linear, branched, fluorinated or functionalised) at the 5 position were synthesised and characterised (51 compounds). Their mesogenic properties were evaluated using differential scanning calorimetry and polarising optical microscopy. Results show that substitution of the 1,3,4-oxadiazole ring for a terminal benzene ring in a conventional p-terphenyl enriched the mesogenic properties. Most of the new oxadiazole compounds exhibit either monotropic or enantiotropic smectic A mesophases with widths ranging from 3 to 50°C. A few compounds (short tailed) exhibit nematic phases and some compounds with branched or fluorinated alkyl substituents at the 5 position are also mesogenic.     

Unprecedented copper(I) bifluoride complexes: synthesis, characterization and reactivity

To be or not to bifluoride: Two synthetic pathways to unprecedented N-heterocyclic carbene copper(I) bifluoride complexes have been developed. Catalytic tests demonstrated that copper(I) bifluorides are very efficient catalysts, which do not require any additional activating agent. The first Cu-catalyzed diastereoselective allylation of (R)-N-tert-butanesulfinyl aldimines was also established. The method enables efficient, simple and general synthesis of enantiomerically enriched homoallylic amines at room temperature in high yields.     

Electrophilic cyclization of (Z)-selenoenynes: synthesis and reactivity of 3-iodoselenophenes

We present here our results of the electrophilic cyclization reaction of (Z)-selenoenynes with different electrophiles such as I(2), ICl, PhSeBr, and PhSeCl. The cyclization reaction proceeded cleanly under mild reaction conditions, and 3-substituted selenophenes were formed in moderate to excellent yields. We observed that the nature of solvent and structure of (Z)-selenoenyne were important to the cyclization reaction. In addition, the obtained 3-iodoselenophenes were readily transformed to more complex products using a metal-halogen exchange reaction with n-BuLi and trapping the intermediate formed with aldehydes, furnishing the desired secondary alcohols in good yields. Conversely, using the palladium or copper catalyzed cross-coupling reactions with terminal alkynes or alkyl alcohols, we were able to convert 3-iodoselenophene to Sonogashira or Ullmann type products, respectively, in good yields.     

Gold(I) phosphido complexes: synthesis, structure, and reactivity

Deprotonation of the phosphine complexes Au(PHR(2))Cl with aqueous ammonia gave the gold(I) phosphido complexes [Au(PR(2))](n)() (PR(2) = PMes(2) (1), PCy(2) (2), P(t-Bu)(2) (3), PIs(2) (4), PPhMes (5), PHMes (6); Mes = 2,4,6-Me(3)C(6)H(2), Is = 2,4,6-(i-Pr)(3)C(6)H(2), Mes = 2,4,6-(t-Bu)(3)C(6)H(2), Cy = cyclo-C(6)H(11)). (31)P NMR spectroscopy showed that these complexes exist in solution as mixtures, presumably oligomeric rings of different sizes. X-ray crystallographic structure determinations on single oligomers of 1-4 revealed rings of varying size (n = 4, 6, 6, and 3, respectively) and conformation. Reactions of 1-3 and 5 with PPN[AuCl(2)] gave PPN[(AuCl)(2)(micro-PR(2))] (9-12, PPN = (PPh(3))(2)N(+)). Treatment of 3 with the reagents HI, I(2), ArSH, LiP(t-Bu)(2), and [PH(2)(t-Bu)(2)]BF(4) gave respectively Au(PH(t-Bu)(2))(I) (14), Au(PI(t-Bu)(2))(I) (15), Au(PH(t-Bu)(2))(SAr) (16, Ar = p-t-BuC(6)H(4)), Li[Au(P(t-Bu)(2))(2)] (17), and [Au(PH(t-Bu)(2))(2)]BF(4) (19).     

The synthesis and reactivity of some 2-amino-5-bromo-],1,3,4-thiadiazoles and the corresponding Δ2-1,3,4-thiadiazolines

The synthesis of some 2-amino-5-bromo-1,3,4-thiadiazoles is reported; these substrates are found to behave as ambidenl nucleophiles in alkylation, aeylation and nitrosation reactions, giving thiadiazoliens along with thiadiazole derivatives. This finding suggests amine-imine tautomerism between these compounds and the corresponding Δ²-1,3,4-thiadiazolines.     

Dipyrrinphenol-Mn(III) complex: synthesis, electrochemistry, spectroscopic characterisation and reactivity

Herein, we report the manganese complex with a novel trianionic ligand, the pentafluorophenyldipyrrinphenol ligand DPPH(3). The X-ray crystal structure reveals that the Mn(III) complex exists in a dimeric form in the solid state. Electrochemical studies indicate two quasi-reversible one electron oxidation processes. EPR data on the one electron oxidised species in solution support the formation of a monuclear Mn complex with an S = 3/2 spin system. Preliminary studies towards epoxidation reactions were tested in the presence of iodosylbenzene (PhIO) and are in favour of an oxygen-atom-transfer (OAT) reaction catalyzed by the Mn(III) complex.