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One or more of the muconaldehyde isomers is a putative product of benzene metabolism. As muconaldehydes are highly reactive dienals and potentially mutagenic they might be relevant to the carcinogenicity of benzene. Muconaldehydes may be derived through the action of a cytochrome P450 mono-oxygenase on benzene oxide–oxepin, which are established metabolites of benzene. Oxidation of benzene oxide–oxepin either by the one-electron oxidant cerium(IV) ammonium nitrate (CAN) or by iron(III) tris (1,10-phenanthroline) hexafluorophosphate in acetone at −78 °C or acetonitrile at −40 °C gave ( E , Z )-muconaldehyde, which was a single diastereoisomer according to analysis by 1 H NMR spectroscopy. Reaction of toluene-1,2-oxide/2-methyloxepin with CAN gave (2 E ,4 Z )-6-oxo-hepta-2,4-dienal. Similarly, the action of CAN on 1,6-dimethylbenzene oxide-2,7-dimethyloxepin gave (3 Z ,5 E )-octa-3,5-diene-2,7-dione. In vivo , benzene oxide–oxepin could suffer one-electron oxidation by cytochrome P450 mono-oxygenase giving ( E , Z )-muconaldehyde. The observations presented may be relevant to the toxicology of benzene oxide–oxepin and other arene oxide–oxepins as we have previously shown that ( E , Z )-muconaldehyde, analogously to ( Z , Z )-muconaldehyde, affords pyrrole adducts with the exocyclic amino groups of the DNA bases adenine and guanine. Independent of their possible toxicological significance, the experiments described provide preparatively useful routes to ( E , Z )-muconaldehyde and its congeners. Methods are also described for the trapping and analysis of reactive benzene metabolites, e.g. using the Diels–Alder reaction with the dienophile 4-phenyl-1,2,4-triazoline-3,5-dione to trap arene oxides and with the diene 1,3-diphenylisobenzofuran to trap enals.

AB Azo-coupling of a series of 6-ketomethylphenanthridines products was performed starting from 6- ketomethylphenanthridines and benzene diazonium chloride. The products were characterised using 1H, 13C and 15N NMR, IR, UV and MS spectroscopic methods. The hydrazoimine forms were the only tautomer present in chloroform solution. Two rotamers were detected in chloroform solutions of the compounds studied. Analysis of the NMR data shows that the ratio of rotamers depends on electron-donating and electron-withdrawing properties of the substituent present in the benzene ring.

Attempted fluorination of β-ketosulfides using Selectfluor™ resulted only in the isolation of the corresponding diaryl disulfides, presumed to arise by decomposition of an unstable fluorinated intermediate. However, fluorination of β-ketosulfones using Selectfluor™ under anhydrous conditions does allow the isolation of both mono-and difluorinated products in moderate to good yields.

The experimental (1)H, (13)C NMR spectra of 3,3-dimethoxy-1-(imidazolidin-2-ylidene)propan-2-one were recorded in CDCl(3) at temperature range 213-323 K. The variable temperature spectra revealed a dynamic NMR effect which is attributed to restricted rotation around the C=C double bond. Fast exchange processes of deuterium atoms between CDCl(3) and 3,3-dimethoxy-1-(imidazolidin-2-ylidene)propan-2-one or fast exchange of proton between nitrogen and oxygen atoms of carbonyl group is also revealed by broadening of N-H (singlet) proton NMR signals. Proton and carbon theoretical chemical shifts of the title molecule were calculated by using RHF and MP2-GIAO levels and different basis sets in gas phase at 298 K. The calculated proton chemical shifts show that the experimental values have no agreement with theoretical values, but for carbon chemical shifts a good agreement achieved by using RHF with 6-31G basis set and MP2/3-21G, 6-31G basis sets. Discrepancies are attributed to either the limitations of calculating program, because the change of the structure while rotation are not considered. The results showed that to select of basis set has more important rule, because RHF-GIAO level calculation with 6-31G basis set in gas phase can excellently reproduce the (13)C NMR spectrum. Moreover, MP2/3-21G, 6-31G calculation has not significant influence on (13)C NMR chemical shifts with respect to RHF-6-31G.

Heterocycles substituted with a nitromethyl (CH2NO2) or phenyl-nitromethyl (CHPhNO2) group were prepared by reaction of a methyl- or phenylmethyl-substituted heterocycle, respectively, with lithium di-isopropylamide followed by quenching the intermediate carbanion with methyl nitrate. Conversion of CH2NO2 attached to an alkyl or aryl moiety into a dichloronitromethyl (CCl2NO2) group was achieved using N-chlorosuccinimide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dichloromethane. Similarly, CH2NO2 attached to an alkyl or aryl group was converted into difluoronitromethyl (CF2NO2) using either 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor™) or N-fluorobenzenesulfonimide with DBU as base and dichloromethane as solvent. Reaction of ω-nitroacetophenone with Selectfluor/DBU in dimethylformamide followed by acidification and distillation gave the parent difluoronitromethane in a useful ‘one-pot’ procedure.

A novel solvatochromic l-(4-dimethylaminophenyl)-2-(5H-phenanthridine-6-ylidene)-ethanone (6-KMPT) dye was synthesized and characterized by means of NMR, IR, mass spectroscopies. Also, it was studied using UV-vis and fluorescence spectroscopic methods in a broad range of solvents. UV-vis results showed that increasing 6-KMPT concentration dose not cause molecular aggregation in chloroform. Varying the temperature in the range from 25 to 55 degrees C dose not have a significant effect on the characteristics bands of the molecule. However, in the presence of surfactant SDS the UV-vis spectrum undergoes drastic alteration. This phenomenon is related to the removal of hydrogen atom from nitrogen atom of phenanthridine moiety. Fluorescence spectroscopic results showed that 6-KMPT has an appreciable fluorescence quantum yield. The effect of excitation wavelength, concentration of 6-KMPT, concentration of oxygen and surfactants (SDS, C(16)TAB, CPC, Brij-35) were studied. Further results showed that the fluorescent behavior of 6-KMPT can be attributed to planarity induced by intramolecular hydrogen bonding which can in turn be destroyed by anionic surfactant SDS. Results showed that oxygen and SDS can be operate as fluorescence quencher compounds for 6-KMPT and Stern-Volmer plot showed a straight line. Fluorescence polarization and anisotropy of 6-KMPT in chloroform strongly depend on concentration. The 6-KMPT exhibits solvent-induced spectral band shifts. By using Lippert equation, the change of dipole moment of 6-KMPT molecule upon excitation was estimated as 6.39 D. Furthermore, absorption, fluorescence emission, Stokes shift values and fluorescence quantum yield (Phi(F)) of 6-KMPT in different solvents of polarity were determined. Maximum Phi(F) value of 0.372 for 6-KMPT molecule was found in ethanol solvent with a Stokes shift of 2446.8 cm(-1). The results of DFT calculations showed that tautomer 2c (enol) energetically is more stable than tautomer 2b (keto) in gas phase whereas it was vice versa in CHCl(3).

Some α-oxoketene-N,S- and N,N-acetals were selectively synthesized in good to excellent yields by the reaction of 1,1-dimethoxy-4,4-di(methylthio)-3-buten-2-one with primary and secondary amines under moderate conditions. Secondary amines in reaction with α-oxoketene dithioacetal yielded double-substitution products exclusively, whereas primary amines under the same conditions yielded the mono-substituted products as exclusive or main products.

Methine and methylene groups attached to a nitro function and heterocycle (and Ph for CH) were rapidly mono- or di-fluorinated by reaction with 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2,2,2]octane bis-tetrafluoroborate (Selectfluor) in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), preferably with ultrasonic irradiation.

3-mercapto-1,2,4-triazoles were condensed with allyl bromide in the presence of a base to afford the corresponding 3-allyl compounds 2. The latter were cyclized regioselectively to give 2,3-dihydro-3-methylthiazolo[3,2-b]1,2,4-triazoles 3.

2- Or 4-Difluoronitromethyl and 2- or 4-fluoronitrobenzyl substituted pyridines, quinolines, phenantheridine, benzothiazol and benzoxazol were synthesized by reaction of the corresponding nitro compounds in the presence of 1-chloromethyl-4-fluoro-1,4-diazoiabicyclo[2,2,2]octane bis(tetrafluoroborate) (Select-Fluor) and ammonium acetate as a base under microwave irradiation. This method is very efficient and the yields were significantly improved in comparison to the previous reports.

[1,3,4]Thiadiazolo[2,3-c][1,2,4]triazin-4-ones were prepared by one pot condensation and cyclization of 4-amino-[1,2,4]triazine-3-thione-5-ones with various aromatic carboxylic acids in the presence of silica gel sulfuric acid in solventless condition.

A series of thioamides, thioureas and thioesters are transformed to their corresponding carbonyl compounds in good to excellent yields with oxone under solid phase conditions, while thioketones remained unchanged under these conditions.

The reaction of oxone as an inexpensive, stable, and commercially available reagent with thiocarbonyl compounds in refluxing acetonitrile has been studied. Primary, secondary, and tertiary thioamides and thioureas are converted to their oxo analogues efficiently. Thiono esters also are transformed to their corresponding esters, while thioketones remained intact under these conditions.

Condensations of anhydrides and quinaldine derivatives are accelerated by microwave irradiation under solvent free conditions in the presence of silica gel as catalyst.

Barium manganate has been used as an inexpensive and convenient reagent for efficient oxidation of a variety of 1,4-dihydropyridine derivatives to pyridine derivatives in refluxing benzene with excellent yields.

Treatment of oximes, phenylhydrazones, p-nitrophenyl-hydrazones, and semicarbazones with quinolinium dichromate (QDC) affords the corresponding carbonyl compounds in high yields under mild conditions.

A combination of NaHSO4.H2O and NaNO2 in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of dihydropyridines to their corresponding pyridine derivatives at room temperature with excellent yields.

A convenient method for the oxidation of various 4-substituted Hantzsch 1,4-dihydropyridines with nicotinium dichromate (NDC) in refluxing acetonitrile is reported. The yields obtained are excellent.

A convenient method for the oxidation of various 4-substituted Hantzsch 1,4-dihydropyridines with nicotinium dichromate (NDC) in refluxing acetonitrile is reported. The yields obtained are excellent.

In an extremely fast method the reaction of hydrazine sulfate with a number of aldehydes and ketones, is accelerated by microwave irradiation under solvent free conditions in the presence of CH3CO2...

Several 2-ketomethylquinolines are synthesized by heating 2-methylquinolines with acyl chlorides, in a conventional microwave oven.

Barium manganate has been used as an inexpensive and convenient reagent for efficient oxidation of a variety of 1,4-dihydropyridine derivatives to pyridine derivatives in refluxing benzene with excellent yields.

A combination of inorganic acidic salts or oxalic acid dihydrate and sodium nitrate in the presence of wet SiO2 was used as an effective oxidising agent for the oxidation of dihydropyridines to their corresponding pyridine derivatives at 40–50 oC with excellent yields.

Heterocycles substituted with a nitromethyl (CH2NO2) or phenyl-nitromethyl (CHPhNO2) group were prepared by reaction of a methyl- or phenylmethyl-substituted heterocycle, respectively, with lithium di-isopropylamide followed by quenching the intermediate carbanion with methyl nitrate. Conversion of CH2NO2 attached to an alkyl or aryl moiety into a dichloronitromethyl (CCl2NO2) group was achieved using N-chlorosuccinimide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in dichloromethane. Similarly, CH2NO2 attached to an alkyl or aryl group was converted into difluoronitromethyl (CF2NO2) using either 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor™) or N-fluorobenzenesulfonimide with DBU as base and dichloromethane as solvent. Reaction of ω-nitroacetophenone with Selectfluor/DBU in dimethylformamide followed by acidification and distillation gave the parent difluoronitromethane in a useful ‘one-pot’ procedure.

3-mercapto-1,2,4-triazoles were condensed with allyl bromide in the presence of a base to afford the corresponding 3-allyl compounds 2. The latter were cyclized regioselectively to give 2,3-dihydro-3-methylthiazolo[3,2-b]1,2,4-triazoles 3.

Benzyltriphenylphosphonium and n-butyltriphenylphosphonium peroxodisulfates are stable and easily prepared oxidising agents. These reagents are able to convert different thioamides and thioureas to their oxygen analogues in good to excellent yields. Thiono esters are also transformed to esters in high yields. Thioketones such as thiobenzophenone and thiofluorenone are converted to their ketones in high yields while, 4-nitrothiobenzophenone, 2-aminothiobenzophenone and 4-chlorothiobenzophenone remained intact in the reaction mixture.

A combination of inorganic chloride salts [e.g. AlCl3, ZrCl4, and ZnCl2] and sodium nitrite in the presence of wet SiO2 was used as an effective oxidising agent for the oxidation of dihydropyridines to their corresponding pyridine derivatives under mild and heterogeneous conditions in moderate to excellent yields.

The synthetic utility of potassium dichromate in the presence of Lewis acids under solid phase conditions is described. This reagent efficiently oxidizes alcohols, acyloins, oximes and semicarbazones to their corresponding carbonyl compounds, while trimethylsilyl and tetrahydropyranyl ethers, ethylene acetals and ketals undergo oxidative deprotection to produce carbonyl compounds efficiently.

In this context with this background, we report here on the synthesis and solid state structure of 2-(4-methoxybenzylthio)-1-phenylethanone. It is a new compound, but derivatives of this type of heterocyclic compounds have shown many interesting biological 1activities. In these compounds two strongly electron with drawing, sulfonyl and carbonyl groups moieties were separated by a methylene group. Calculations showed that the conformation of b-ketosulfides and b-ketosulfones is strongly influenced by two cross donor-acceptor interactions existing between pairs of the SO

The crystal structure of a new benzoic acid cocrystal with a benzothiazole-based acceptor, 2-(benzothiazol-2-yl)-1-phenylethenyl benzoate (BEB), with the 1:1 stoichiometry, C7H6O2 + C22H15NO2S, has been determined. In the crystal lattice every benzoic acid molecule is associated to a (BEB) molecule via strong O-H…N and weak C-H…O intermolecular hydrogen bonds and two short intermolecular O-H…π contacts. In the structure of (BEB), due to an intra-molecular non-bonded S…O interaction, the intra-molecular S…O(1) non-bonded distance is shorter than the sum of the corresponding van der Waals radii and the Z configuration is preferred for the ethylenic double bond.

The title compound I, C21H14ClNO, was synthesized and the structure was investigated by X-ray crystallography. The compound crystallizes in the monoclinic crystal system and the space group P21/c with cell parameters a = 14.158(2)A, b = 6.9362(12)A, c = 15.660(3)A, β = 96.608(3)°, Z = 4 and V = 1527.6(4)A3. The nitrogen, C(13), C(14) and C(15) atoms in the structure are coplanar and π-delocalization exists in I. The tautomer enamino ketone of I is stablized by both π-delocalization and intra-molecular hydrogen bonds.

The title compound, 2,2-bis(6-hydroxy-biphenyl-3-yl)-1H-indene-1,3(2H)-dione (1), crystallizes in the monoclinic space group P21 with cell parameters a = 9.3606(7), b = 26.403(2), c = 11.0719(7), β = 97.757(4)°, V = 2711.4(3)A3 and Z = 4. The asymmetric unit comprises two of crytallographically independent molecules of (1) and one molecule of dichloromethane, as packing solvent without any formation of intermolecular hydrogen bonds.

The crystal structure of 1,1-dimethoxy-4-phenylamino-4-methylthio-3-buten-2-one I, C13H17NO3S, has been determined. The title compound is packed in columns along the a axis. C(4), C(5), C(6) and nitrogen atoms in the structure are coplanar and π-delocalization exists in I. The tautomer enamino ketone of I is stablized by π-delocalization and intra-molecular hydrogen bond.

A new acyclic nucleoside phosphonate (13) containing an adenine moiety was synthesized, which acted as an excellent inhibitor of calf mucosal adenosine deaminase. This inhibitory property allows it to exert great synergistic effect on certain antiviral agents (e.g., ara-A, 37). Phosphonate 13 was not phosphorylated by the bovine brain guanylate kinase nor by 5-phosphoribosyl 1-pyrophosphate synthetase. Syntheses of biologically active nucleotide phosphonate 40 and its phosphonoamidate derivative 42 were accomplished, which showed remarkable activity against herpes viruses and exhibited low host cell toxicity. 3'-Azido-nucleoside phosphonate 20 and 3'-fluoronucleoside phosphonate 32, as well as the corresponding dinucleotide analogs 47 and 48, and their respective phosphonoamidates 53-56 were also synthesized as new compounds, among which phosphonoamidates 53-56 showed potent activity against human immunodeficiency virus. Phosphonoamidates 55 and 56 bearing a methyl D-alaninate moiety exhibited less cellular toxicity than 53 and 54 bearing a methyl L-alaninate moiety. Nucleotide phosphonate 40 as well as dinucleotide phosphonates 47 and 48 were found susceptible to degradation by phosphodiesterases. Their respective phosphonoamidates 42 and 53-56, however, were completely resistant to snake venom and spleen enzymes.

Several 2-ketomethylquinolines are synthesized by heating 2-methylquinolines with acyl chlorides, in a conventional microwave oven.

A variety of Hantzsch 1,4-dihydropyridines are oxidized to their corresponding pyridines in excellent yields by 3-carboxypyridinium chlorochromate.