AM1 CI and ZINDO/S study of quaternary salts of diazaphenanthrenes with haloalkanes

For quaternary salts of diazaphenanthrenes 1-3 with methyl iodide 4-6, diiodomethane 7-9 and 1,2-dibromoethane 10-12 UV spectral values have been calculated by AM1 CI, and in the case of 4-6 also with ZINDO/S method. Correlations of experimental and calculated wavenumber values of considered compounds show good compatibility. For geometry optimisation of 4-9 the AM1 CI method has been used.     

EXCITED STATES OF SIX-MEMBERED N-HETEROCYCLES. FLUORESCENCE, PHOSPHORESCENCE AND ACID-BASE EQUILIBRIA OF FIVE MONO- AND DIAZA-PHENANTHRENES IN THE LOWEST EXCITED (τ,τ) STATES

Abstract— Acid-base equilibria of five azaphenanthrenes (1-and 4-aza; 1,10-, 1,7-, and 4,7-diaza) in the two lowest excited (τ,τ) states have been determined by Förster's cycle. Pure electronic levels of the free bases and their conjugate acids have been located from the absorption, fluorescence and phosphorescence spectra. In diazaphenanthrenes the increase of the first pK_a and the decrease of the second pK_a under excitation has been observed, and an explanation is offered. In many cases the reactivity of the molecule excited to the lowest triplet state differs considerably from that in the ground state. The Pariser-Pam-Pople (PPP) calculations of the free bases have been performed. From the theoretical results, the changes of the net charge on nitrogen atoms under excitation and the magnitude of the S-T splitting in the L_a and L_b states have been discussed and compared with experiment.     

Benzo[h]cinnolin

The synthesis of benzo[h]cinnolin ( 3 ) is reported. Its spectroscopic properties (uv, luminescence, pmr, ms) are similar to the other diazaphenanthrenes containing a diazine ring. The lowering of the basicity of 3 compared with a monoazaphenanthrene like other diaza-aromatic compounds appears to be due to an electrostatic field effect and not to an inductive effect.     

The13C NMR, UV and IR spectra of 2-fluoropyridine methyl derivatives

¹³C NMR, UV, and IR spectra of methyl derivatives of 2-fluoropyridine have been recorded. The influence of the substituents on the spectral characteristics of the compounds has been discussed. The electronic spectra have been calculated by a modified INDO method. Transition energies, intensities, and assignments are compared with UV spectra.Department of Organic Chemistry, Academy of Economics, Pl-53 342 Wroclaw, Poland Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 763–773, June, 1999.     

Synthesis and photophysics of acridine derivatives

Highly fluorescent acridine derivatives were prepared by a multistep synthesis starting from 2-chlorobenzoic acid and the approapriate (aminophenyl)alkanoic acid by means of a modified Ullmann-Jourdan reaction followed by a cyclodehydration step, and by amination in the case of aminoacridine analogues. The obtained derivatives were subjected to photophysical studies (absorption and fluorescence). The compounds displayed interesting absorption behavior and high quantum yield of fluorescence. Acridine analogues bearing a free carboxylic group can serve as effective fluorescent probes in conformation analysis of peptides.Faculty of Chemistry, University of Gdansk, Sobieskiego 18 80-952, Gdansk, Poland; e-mail: neta@chemik.chem.univ.gda.pl Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 914–921, July, 2000.     

Electronic spectra and structure of methyl derivatives of 4-nitropyridine N-oxide

The UV spectra of seven methyl derivatives of 4-nitropyridine N-oxide in ethanol have been examined. The electronic spectra were calculated by a modified INDO method. Transition energies, intensities and assignments were compared with UV spectra. Spectroscopic manifestations of intramolecular interaction indicate that methyl groups modify the electronic interaction between the N-oxide and NO₂ groups mainly through a steric strain.Department of Organic Chemistry, University of Economics, Pl-53342 Wroclaw, Poland. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 786–793, June, 2000.     

Massenspektrometrie isomerer Diazaphenanthrene—I

The mass spectra of five diazaphenanthrenes formed by photochemical cyclodehydrogenation of styryl diazines are investigated. It is shown that fragmentation of these compounds starts almost exclusively at the heterocyclic part of the molecule and proceeds by competitive α-cleavage. From the intensity ratios of the ions [M ? H˙]⁺, [M ? HCN]⁺˙, [M ? N₂]⁺˙ and [M ? 2 HCN]⁺˙ generated in this way, each isomer can unequivocally be identified.     

Cyclic voltammetry for a preliminary study of appropriate electro-synthesis reactions of naphthalene derivatives

Cyclic voltammetry on a glassy carbon electrode was used for studies of electro-oxidations of several naphthalene derivatives. The number of electrons participating in the primary reaction at the electrode is derived using the modified Randles-Ševčik equation applied to a series of experimental data of peak current intensity vs. the potential rate. The mechanism of electro-oxidation of two natural products, juglone and lawsone, is discussed with respect to hydrogen bond formation. Correspondence: Roman E. Sioda, Department of Analytical Chemistry and Electrochemistry, Institute of Chemistry, University of Podlasie, ul. 3 Maja 54, 08-110 Siedlce, Poland. An erratum to this article can be found online at http://dx.doi.org/.     

Synthesis of isoxazolines from nitrile N-oxides generated from nitroalkenes

In this review, information on the production of isoxazolines and condensed isoxazoline systems by the intramolecular 1,3-bipolar cycloaddition of unsaturated nitrile N-oxides generated in situ from nonconjugated nitroalkenes is generalized and systematized. The isoxazoline derivatives formed as the result of these reactions are promising synthons in the synthesis of various natural compounds and their analogues.Krakow Polytechnic Institute, Poland. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 291–305, May–August, 1992.     

Zero field splittings in the lowest excited triplet states of aza- and diazaphenanthrenes and their protonated species

ESR spectra of the lowest excited ππP^* triplet states of a series of azaphenanthrenes (AP) and diazaphenanthrenes (DAP) are measured in rigid glasses. The zfs parameters are evaluated for 4-AP, 1,7-DAP, 4,7-DAP, 1,10-DAP and for their mono- and diprotonated species, BH⁺ and BH²⁺₂. The zfs parametesr of the bases are a litte higher than those of phenanthrene. On single protonation they fall below the latter values. Second protonation causes again an increase in zfs, with the exception of the 1,10-DAP divalent cation which behaves peculiarly. Spin-orbi contributions to the zfs seem not to be responsible for the observed differences.     

Absorption spectra of nitro derivatives. 2-alkylamino-4-nitropicolines and their N-oxides

The UV spectra of 15 2-N-substituted 4-nitropicolines and their N-oxides in ethanol have been determined. The spectra of all investigated compounds with the exception of 2-alkylnitramino-4-nitropicolines contain three main bands: two absorption bands are attributed to ^* excitation of the -electron of the aromatic system. The third ICT in the longest wavelength region is assigned to the 4-nitro group via the pyridine ring. The bands in the spectra of 3-methyl derivatives are characterized by smaller intensity than 5-methyl derivatives due to the disturbance of the mutual electronic interaction of the substituent by the stericortho effect.Department of Organic Chemistry, University of Economics, PL-53-342 Wroclaw, Poland. Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 774–779, June, 1998.     

Synthesis and conversions of 2-carbethoxy-3-bromomethyl-7-chlorobenzofuran

2-Carbetlzoxy-3-broinomethy1-7-chlorobenzofuran has been synthesized and its conversions studied.Chemical Faculty, N. Kopernik University, Torun87-100, Poland. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 756–759, June, 1994. Original article submitted April 12, 1993.     

Microwave-assisted synthesis of derivatives of khellinone under phase-transfer catalytic conditions

The microwave-assisted synthesis of four new 5-acetyl-4,7-dimethoxy-6-hydroxybenzofuran (khellinone) analogs is described. The structures of the obtained derivatives in the solid state are evaluated on the basis of ¹³C CP/MAS NMR spectra and theoretical calculations at DFT level. A single crystal X-ray diffraction structure is presented for 8-acetyl-7-hydroxy-4-methylcoumarin. 1,4-Bis(5-acetyl-4,7-dimethoxybenzofuran-6-yloxy)butane was evaluated for potential anticancer activity in an in vitro screening panel of 60 human tumor cell lines. Selected leukemia, non-small cell lung cancer, CNS, melanoma, ovarian, and breast cancer cell lines were sensitive to this compound. Correspondence: Elżbieta Hejchman, Department of Organic Chemistry, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1, 02-097 Warsaw, Poland.     

Synthesis and Antiviral Activity of 1-{[2-(Phenoxy)ethoxy]methyl}uracil Derivatives

The synthesis of novel 1-{[2-(phenoxy)ethoxy]methyl}uracil derivatives with different substituents in positions and 6 of the pyrimidine ring has been carried out. It has been shown that the alkylation of trimethylsilyl derivatives of uracil with 2-(4-chlorophenoxy)- and 2-(4-methylphenoxy)ethoxymethyl chloride under Hilbert-Johnson reaction conditions gives N₍₁₎-substitution products. It was found that the 1-{ [2-(phenoxy)ethoxy]methyl}uracil derivatives show viral inhibition properties relative to human immunodeficiency type 1 virus in vitro. The most active compounds are 5-bromo-6-methyluracil derivatives which suppress viral reproduction by 50% at 7.2 and 7.8 micromolar concentrations.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 726–731, May, 2005.     

A Chiral Recognition Mechanism Proposed for Resolving π-Acidic Racemates on π-Acidic Chiral Stationary Phases Derived from (S)-Leucine

A chiral recognition mechanism which can rationalize the resolution of N-(3,5-dinitrobenzoyl)-α-amino amides on chiral stationary phases (CSPs) obtained from N-(3,5-dinitrobenzoyl)leucine amide derivatives has been proposed on the basis of the chromatographic resolution behavior of various N-(3,5-dinitrobenzoyl)-α-amino acid derivatives and N-(various benzoyl)leucine N-propyl amides. The proposed chiral recognition mechanism utilizes two hydrogen bonding interactions between the CSP and the analyte and a π-π donor-acceptor interaction between the N-(3,5-dinitrobenzoyl) groups of the CSP and the analyte. From the chiral recognition mechanism proposed, it has been concluded that the resolution of π-acidic N-(3,5-dinitrobenzoyl)-α-amino acid derivatives on π-acidic CSPs derived from N-(3,5-dinitrobenzoyl)leucine amide delivatives is not unusual, but is merely the extension of the resolution of the π-basic racemates on π-acidic CSPs. However, the chromatographic behavior of the resolution of N-(3,5-dinitrobenzoyl)phenylglycine derivatives on CSPs derived from N-(3,5-dinitrobenzoyl)leucine amide derivatives is different from that of the resolution of other N-(3,5-dinitrobenzoyl)-α-amino acid derivatives. To rationalize this exceptional behavior, a second chiral recognition mechanism which utilizes two hydrogen bonding interactions (which are different from those of the first chiral recognition mechanism) between the CSP and the analytes and a π-π donor-acceptor interaction between the N-(3,5-dinitrobenzoyl) group of the CSP and the phenyl group of the analytes has been proposed to compete with the first chiral recognition mechanism. In this instance, it has been proposed that the separation factors and the elution orders of the resolution of N-(3,5-dinitrobenzoyl)phenylglycine derivatives are dependent on the balance of the two competing chiral recognition mechanisms.     

Catalytic transfer hydrogenation of cyclodextrin azides and benzylated glucose derivatives

Debenzylation by catalytic transfer hydrogenation (CTH) of various organic compounds is a simple, fast, and safe method. Though CTH is widely used in reductions, only few data are available for the conversion of azides to amines. The number of usable transfer compounds is limited in cases of sugar derivatives, as the most common transfer materials, e.g. hydrazine hydrate or formic acid, can compete in side-reactions. The present study explores the limits of the reaction parameters and transfer compounds.A part of this publication was presented at EUROCARB VII, Cracow, Poland, 22–27 Aug. 1993.Dedicated to Professor József Szejtli.     

Synthesis and iNOS/nNOS inhibitory activities of new benzoylpyrazoline derivatives

A series of new Δ²-pyrazoline derivatives has been synthesized by means of a 1,3-dipolar-cycloaddition reaction. Ethyl 3-(5-methoxy-2-nitrobenzoyl)-Δ²-pyrazoline-5-carboxylate (5a) has been designed for the formation of the benzoylpyrazoline system present in these derivatives. Two synthetic routes have been utilized changing the starting products in the cycloaddition reaction. In both routes, the majority product obtained was only a Δ²-pyrazoline. The intermediate ethyl 1-acyl-3-(2-nitrobenzoyl-5-substituted)-Δ²-pyrazoline-5-carboxylate derivatives have been transformed into the final compounds by means of several chemical treatments. The compounds have been biologically evaluated as inhibitors of nitric oxide synthase (NOS), showing better affinity towards the inducible NOS isoform than versus neuronal NOS.     

5-nitro-5-(1′-cyclohexenyl)- and 5-nitro-5-(1′-cycloheptenyl)-3-benzyl- and 3-cyclohexyl tetrahydro-1,3-oxazines

1-(Cyclohexenyl- and 1-cycloheptenylnitromethane have been used as starting substances to yield 2-nitro-2-(1′-cyclohexenyl)- and 2-nitro-2-(1′-cycloheptenyl)-propanediol-1,3 (B) respectively. By reacting them with formaldehyde and benzylamine or formaldehydes and cyclohexylamine, derivatives of tetrahydro-1,3-oxazine (B) have been prepared. Acid hydrolysis of tetrahydro-1,3-oxazine derivatives results in the formation of 3-hydroxy-2-nitro-2-(1′-cyclohexenyl)- and 3-hydroxy-2-nitro-2-(1′-cycloheptenyl)-propylamine derivatives (E). Both aminoalcohols (E) react with formaldehyde to again yield tetrahydro-1,3-oxazine derivatives (C).

Infra-red spectra of C and E and their hydrochlorides D and F were examined and structure assignments made of the principal bands.     

Synthesis of D-Glucosamine-Modified Benzo[d][1,2]selenazol-3-(2H)-one Derivatives

A new class of organoselenium-saccharide derivatives, 2-amino-2-deoxy-β-D-glucose-modified benzo[d][1,2]selenazol-3-(2H)-one derivatives, has been synthesized via the cyclization reaction of 2-(chloroseleno)benzoyl chloride and O-protected D-glucosamine derivatives. An efficient synthetic method for the preparation of this type of compounds was developed. It has been found that acetone can react with the chloroseleno group under basic conditions, and organoselenium-saccharide derivatives with free hydroxy groups were obtained only when the OH-1 group of the saccharide was protected.     

Synthesis of a novel spiro bisphosphinamidite ligand for highly enantioselective hydrogenation

A novel chiral bisphosphinamidite ligand SpiroNP has been synthesized. The rhodium complex of this ligand has been found to be highly active and enantioselective in the asymmetric hydrogenation of (Z)-2-acetamidoacrylic acid derivatives and α,β-unsaturated carboxylic acid derivatives.