Claudia Reidlinger

Structure-color correlations of penta- and heptamethines: Syntheses with nitriles XCIV

Abstract The synthesis of asymmetric cyanine dyes (penta- and heptamethines), prepared by coupling Fischers base with indandione, benzo[b]thiophene and pyrazole derivatives via a C-1 unit, is described. Three different synthetic strategies for substituted polymethines are presented. Dye characteristics are given and the correlation between the chemical structures and the dye properties are discussed by means of semiempirical PPP calculations.

Push–pull dyes containing malononitrile dimer as acceptor: synthesis, spectroscopy and quantum chemical calculations

Abstract The effect of structural variations of either the donor (number and position of methoxy groups, replacement of the aryl by Fischers base) or the acceptor moiety (bisacylation of the amino group, extension of the conjugated system by condensation with dimethylformamide–dimethylacetale) of a series of dyes containing malononitrile dimer as acceptor is investigated both experimentally and computationally. Semiempirical (AM1) and ab initio (HF/6-31G ∗ and HF/3-21G) calculations are used for a conformational analysis of the acceptor groups and model systems thereof. Electronic excitation energies are obtained by ZINDO, ab initio CIS/6-31+G ∗ and time-dependent density functional theory (TDDFT(B3LYP)/6-31+G ∗ ) computations. Inclusion of solvent effects is important for a reliable description of the trends observed in the experimental absorption spectra by ZINDO. Methoxyaryl, even polysubstituted, derivatives absorb at significantly shorter wavelengths than the corresponding p-dimethylamino compounds. Replacement of the p-dimethylaminoaryl donor by Fischers base leads to a bathochromic shift, as does the bisacylation of malononitrile dimers amino group. Functionalization by condensation with dimethylformamide–dimethylacetale generally has only a small and irregular effect on absorption spectra.

Cyanoacetophenone as a Synthon for 1,4,5-Substituted Pyrazoles

Summary. An improved synthesis of cyanoacetophenone is described. Cyanoacetophenone was reacted with dimethylformamide-dimethylacetal and diphenylformamidine to give 1-dimethylamino-3-oxo-3-phenyl-1-propene-2-carbonitrile and 1-anilinomethylene-3-oxo-3-phenyl-1-propene-2-carbonitrile. Reaction of 1-dimethylamino-3-oxo-3-phenyl-1-propene-2-carbonitrile with hydrazines gave either 1-substituted 5-amino-4-benzoylpyrazoles or (1-substituted) 4-cyano-5-phenylpyrazoles. Treatment of 1-anilinomethylene-3-oxo-3-phenyl-1-propene-2-carbonitrile with phenylhydrazine also yielded 5-amino-4-benzoyl-1-phenylpyrazole, whereas reaction with unsubstituted hydrazine afforded 4-cyano-5-phenylpyrazole.Zusammenfassung. Eine verbesserte Darstellung von Cyanacetophenon wird beschrieben. Cyanacetophenon reagierte mit Dimethylformamid-dimethylacetal bzw. Diphenylformamidin zu 1-Dimethylamino-3-oxo-3-phenyl-1-propen-2-carbonitril und 1-Anilinomethylen-3-oxo-3-phenyl-1-propen-2-carbonitril. Durch Umsetzung von 1-Dimethylamino-3-oxo-3-phenyl-1-propen-2-carbonitril mit Hydrazinen wurden entweder 1-substituierte 5-Amino-4-benzoylpyrazole oder (1-substituierte) 4-Cyano-5-phenylpyrazole erhalten. Reaktion von 1-Anilinomethylen-3-oxo-3-phenyl-1-propen-2-carbonitril mit Phenylhydrazin ergab ebenfalls 5-Amino-4-benzoyl-1-phenylpyrazol, während unsubstituiertes Hydrazin zu 4-Cyan-5-phenylpyrazol reagierte.

Parallel Microwave Synthesis of 2-Styrylquinazolin-4(3H)-ones in a High-Throughput Platform Using HPLC/GC Vials as Reaction Vessels

The application of a high-throughput reaction platform for performing parallel microwave synthesis in sealed HPLC/GC vials contained in a strongly microwave-absorbing silicon carbide plate is described. The use of aluminum crimp caps with PTFE coated silicone septa in combination with an appropriate plate sealing mechanism allows processing of reaction volumes from 0.5-1.5 mL at temperatures of approximately 250 degrees C and pressures of up to approximately 20 bar. A library of 39 2-styrylquinazolin-4(3H)-one derivatives was prepared in a two-step/one-pot parallel fashion involving the initial three-component condensation of four anthranilic acids with acetic anhydride and ammonium acetate at 250 degrees C for 30 min. This was followed by catalyst-free condensation of the resulting 2-methylquinazolinones with a selection of 15 aromatic aldehydes. Compared to single-mode sequential microwave synthesis, the overall processing times for library synthesis could be significantly reduced.

Macrocyclic systems containing 2,6,9-trioxabicyclo[3.3.1]-nona-3,7-dienes as chiral spacer groups: Synthesis, stereochemical features and preliminary complexation properties

Novel 2:2-macrocycles bearing bridged concave 2,6,9-trioxabicyclo[3.3.1]nona-3,7-dienes as chiral spacer units were obtained by cyclocondensation reaction of the chiral bisacid chloride and the corresponding diols, while use of methylene diamines instead of diols afforded 1:1 macrocycles only. Applying the same, but now template-assisted, experimental procedure to the reaction of the bisacid chloride with triethylene glycol brought about a significant increase in yield as well as a suitable simplification of the work-up during preparation and separation of the corresponding 1:1 as well as 2:2 macrocycles, when compared to results reported previously. HPLC separation on chiral columns revealed the presence of diastereoisomers [R,R(S,S)- and R,S-(meso)-forms] for all 2:2 macrocycles, which was further evidenced by the CD spectrum of one of those species as an example. Preliminary ESI-MS experiments indicated strong complexation abilities of the sulphur-containing ligand towards Ag(I), Cu(II) and Au(III) ions.

Nonlinear optical properties of diazabutadienes and -hexatrienes; experimental and computational aspects

Donor-acceptor substituted diazabutadienes and -hexatrienes were prepared by straightforward procedures and their linear optical (UV-vis) and nonlinear optical second harmonic generation (SGH) properties investigated in a combined theoretical and experimental study. Theoretical and experimental results were in reasonable agreement. For the compounds in this study, which contained a p-nitrophenyl group as electron acceptor, the p-dimethylaminophenyl group was the most powerful electron-donating group, leading to the highest maximum absorption wavelengths, as well as to the maximum SHG efficiency.

Possible Rearrangements During the Synthesesof Di- and Trisubstituted Pyrazoles

Summary. The reaction of ethoxymethylene malononitrile and ethoxymethylene cyanoacetic acid ethylester with substituted hydrazines to substituted 5-aminopyrazoles is described. The influence of different substituents on possible migrations during the ring closure was studied..Zusammenfassung. Die Reaktion von Ethoxymethylenmalodinitril und Ethoxymethylencyanessigsäureethylester mit substituierten Hydrazinen zu substituierten 5-Aminopyrazolen wird beschrieben. Der Einfluß unterschiedlicher Substituenten auf mögliche Wanderungen während des Ringschlusses wurde untersucht..

Fischer's base as an electron donor for new penta- and heptamethines

Abstract Asymmetric cyanine dyes (penta- and heptamethines) prepared by coupling Fischers base or Fischers aldehyde with malononitrile dimer or analogous compounds are described. Dye characteristics are given and structure-color correlations are discussed.

Beiträge zur Chemie der Enaminoketone, 15. Mitt.: Die Dreikomponentensynthese von Hydrazinomethylenchromandionen und eine reduktive N-N-Bindungsspaltung von Phenylhydrazin

ZusammenfassungDie Dreikomponentenreaktion von 4-Hydroxycumarin, Orthoameisensäuretriethylester und verschieden substituierten Hydrazinen wird beschrieben.p-Nitrophenylhydrazin, Hydrazincarbonsäureester, Benzhydrazid und Phenylsemicarbazid liefern die erwarteten Hydrazinomethylenchromandione2a–f. Durch Umsetzung von 4-Hydroxycumarin-3-carbaldehyd mit Hydrazinen sind ebenfalls Hydrazinomethylenverbindungen (2g–k) zugänglich. Die Umsetzung von 4-Hydroxycumarin mit Orthoester und Phenylhydrazin oderp-Tolylhydrazin führt jedoch nicht zu2, sondern zu den Anilinomethylenchromandionen6a–b. Dies bedeutet eine reduktive Spaltung der N-N-Bindung unter sehr milden Reaktionsbedingungen zu Anilin und Ammoniak.SummaryThe three-component reaction of 4-hydroxycoumarin, ethylorthoformiate, and different substituted hydrazines is described.p-Nitrophenylhydrazine, hydrazides and phenylsemicarbazide lead to the expected hydrazinomethylene-chromandiones2a–f. Reaction of 4-hydroxycoumarin, ethylorthoformiate, and phenylhydrazine orp-tolyl-hydrazine does not yield2, but the anilinomethylene-chromandiones6a–b. This indicates a reductive N-N bond cleavage to aniline and ammonia under mild conditions.