Published by De Gruyter

Volume 73 Issue 7 - Special Issue: Iminium Salts and Imines

Issue of Zeitschrift für Naturforschung B

Contents
Journal Overview

Publicly Available July 5, 2018

Frontmatter

Page range: i-iv

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Publicly Available July 5, 2018

Preface

June 8, 2018

The role of iminium salts, imines and related compounds in chemistry

René Wilhelm

Page range: 429-429

Original Articles

June 8, 2018

A simple route to 2-aryl-substituted naphtho[2,1-e][1,2,4]triazinium and naphtho[2,1-e][1,2,3,4]tetrazinium salts from 1-arylazo-substituted 2-naphthylamines

Xiuling Yu, Peter Metz, Horst Hartmann

Page range: 431-435

Abstract

1-Arylazo-substituted 2-naphthylamines, which are easily obtainable by the coupling of arene diazonium salts with 2-aminonaphthalene-sulfonic acid, can be transformed by reaction with reactive carboxylic acid derivatives or nitrosation reagents into novel 2-aryl-substituted naphtho[2,1- e ][1,2,4]triazinium and naphtho[2,1- e ][1,2,3,4]tetrazinium salts, respectively.

June 13, 2018

Orthoamide und Iminiumsalze, XCII. Synthese und Reaktionen von Orthoamiden aus ethinylierten Terpenderivaten^a

Willi Kantlehner, Jochen Mezger, Ralf Kreß, Wolfgang Frey

Page range: 437-455

Abstract

β -Ionone and camphor were ethynylated to give the alkynols 14 , 16 , 17 which can be transformed to the alkynolethers 5b , 5i , 5j , 5k , 5l , 5m by treatment with dimethylsulfate and chlorotrimethylsilane, respectively. From the alkynolethers 5h , 5i , 5j / 5k , 5l / 5m the orthoamide derivatives 4h , 4i , 4j / 4k , 4l / 4m can be prepared by treatment with N,N,N ′ ,N ′ ,N ″ ,N ″-hexamethylguanidinium chloride ( 8 ) in the presence of sodium hydride. The orthoamides 4h , 4i react with the sulfonamide 30 under condensation yielding the N -sulfonylated acrylamidines 31 , 32 . From the orthoamide 4h and p -nitroaniline the propiolamidine 29 could be obtained. The orthoamides 4j / 4k and 4l / 4m , react with benzamidine to give the pyrimidines 33 , 34 , respectively. In the reaction of malonodinitrile ( 9a ) with the orthoamides 4i and 4j / 4k , mixtures of 1,1-diamino-1,3-butadienes 36 , 38 and 1,3-diamino-1,3-butadienes 37 and 39 are produced, respectively. From CH 2 -acidic compounds as ethylcyanacetate ( 9b ), diethyl-malonate ( 9c ) and nitromethane ( 9d ) and the orthoamide 4i the 1,1-diamino-1,3-butadienes 36b – d were produced. The pyridone derivative 40 can be prepared from cyanoacetamide ( 9e ) and the orthoamide 4i . The condensation of the orthoamides 4j / 4k with cyanoacetamide ( 9e ) affords a mixture of the pyrimidone 41 and the nicotinonitrile 42 .

June 30, 2018

Orthoamide und Iminiumsalze, XCIII. Darstellung und Umsetzungen eines vinylogen Orthoamid-Derivats der Kohlensäure mit CH₂-aciden Verbindungen^a

Markus Vettel, Hans-Jürgen Bräuner, Willi Kantlehner

Page range: 457-466

Abstract

The preparation of the vinylogue guanidinium salt 10c is described. The reaction of the vinylogue orthocarbonic acid amide derivative 12 with CH 2 -acidic compounds 14a–s affords the ketene aminals 15a–s . At room temperature the succinimide 19a is deprotonated by 12 to give the vinylogue salt 10e . The bis-ketene aminal 20 is formed in the reaction of 19a with 12 at elevated temperatures. Succinic acid esters 21 do not react cleanly with the orthoamide 12 , but mixtures of ketene aminals 23 and bis-ketene aminals 22 are formed. From succinodinitrile ( 24 ) and 12 the bis-ketene aminal 25 could be obtained, which is also accessible by the action of the salt 10c with 24 in the presence of sodium hydride.

June 8, 2018

Synthesis of functionalized pyrazole derivatives by regioselective [3+2] cycloadditions of N-Boc-α-amino acid-derived ynones

Eva Pušavec Kirar, Uroš Grošelj, Amalija Golobič, Franc Požgan, Sebastijan Ričko, Bogdan Štefane, Jurij Svete

Page range: 467-480

Abstract

[3+2] cycloadditions of ynones derived from glycine and ( S )-alanine and some other dipolarophiles with azomethine imines, nitrile oxides, diazoacetate, and azidoacetate were studied. The dipolarophiles were obtained from α -amino acids, either by the reduction of the carboxy function with ethynylmagnesium bromide or by propiolation of the amino function. Cu-catalyzed cycloadditions of ynones to azomethine imines were regioselective and gave the expected cycloadducts as inseparable mixtures of diastereomers. In some instances, further oxidative hydrolytic ring-opening took place to afford 3,3-dimethyl-3-(1 H -pyrazol-1-yl)propanoic acids. Acid-catalyzed cycloadditions of 3-butenone were also regioselective and provided mixtures of diastereomeric cycloadducts, which were separated by chromatography. In the reactions of title ynones with alkyl diazoacetates, in situ -formed benzonitrile oxides, and tert -butyl azidoacetate, all cycloadducts were obtained as single regioisomers. The structures of all novel compounds were established by nuclear magnetic resonance and X-ray diffraction.

May 18, 2018

Chemistry and spectroscopy of cross-conjugated and pseudo-cross-conjugated quinolinium-ethynyl-benzoate mesomeric betaines

Sviatoslav Batsyts, Francisco J. Ramírez, Juan Casado, Jan C. Namyslo, Andreas Schmidt

Page range: 481-491

Abstract

The three isomers 1-methylquinolinium-2-, 3-, and 4-ethynyl(phenyl-4-carboxylates) belong to two distinct types of heterocyclic mesomeric betaines. The quinolinium substituted in position 3 is a cross-conjugated mesomeric betaine (CCMB), whereas the quinolinium derivatives substituted in positions 2 and 4 are members of the class of pseudo-cross-conjugated mesomeric betaines (PCCMBs). While the charges are strictly separated within the common π-electron system of the CCMB according to the canonical formulae, the charges are effectively but not exclusively delocalized in the PCCMBs because cumulenoid resonance forms including electron sextet structures without external octet stabilization can be formed in accordance with the definition of PCCMBs. As a consequence, despite being closely related structures, the three isomers differ in their chemical and spectroscopic behaviors. Thus, on trying to hydrolyze the ester group of the methyl quinolinium-2-ethynyl-benzoate into the corresponding acid by subsequent treatment with sodium hydroxide in methanol and aqueous hydrochloric acid at pH 3, the acetal methyl 1,1-dimethoxy-2-(quinolinium-ylidene)ethyl]benzoate and the corresponding β -enamino carbonyl compound were formed, respectively. The corresponding acids of the 2- and 4-substituted quinolinium-ethynyl-benzoates were obtained by a modified procedure. On deprotonation, the resulting cross-conjugated quinolinium-3-ethynyl-benzoate betaine proved to be stable, whereas the corresponding pseudo-cross-conjugated quinolinium-2- and -4-ethynyl-benzoate betaines decomposed. Frontier orbital profiles were calculated, and IR and Raman spectra of the starting materials were measured and calculated to analyze the differences of CCMBs and PCCMBs of mesomeric betaines possessing triple bonds. A higher contribution of the cumulenoid resonance forms to the overall structure of the PCCMBs was determined.

June 8, 2018

Integrating the fluorene substructure into azaacenes: syntheses of novel fluorophores

Dörthe Jakobi, André Schumann, Rainer Beckert

Page range: 493-500

Abstract

In this study, we report on the syntheses of novel angular fused azaacenes. For this purpose, the synthesis of the bis -diamine 2 (TABEF) could be shortened and optimized. The condensation reaction of 2 with different types of 1,2-diketones yielded new azaacene derivatives of types 10 , 11 and 12 . Analogously, 2 was cyclized with thionyl chloride to give the piazthiol derivative 13 . The optical and electrochemical properties of all new compounds were investigated by UV/Vis absorption, fluorescence emission spectroscopy and cyclovoltammetric measurements.

June 12, 2018

Thermal metal-free [2+2] cycloaddition of acetylenedicarboxylates to polysubstituted butadienes

Benjamin Prek, Marta Počkaj, Willi Kantlehner, Branko Stanovnik

Page range: 501-513

Abstract

The thermal metal-free [2+2] cycloadditions of electron-poor acetylenes to some polysubstituted systems with conjugated double bonds (polysubstituted butadienes) are described.

June 5, 2018

Protic ionic liquids as catalysts for a three-component coupling/hydroarylation/dehydrogenation tandem reaction

Maren Muntzeck, René Wilhelm

Page range: 515-519

Abstract

Protic ionic liquids with nitrate anions were used as solvents and catalysts for a three-component oxidative dehydrogenation tandem reaction via the coupling and hydroarylation of benzaldehyde, aniline, and phenylacetylene to a quinoline derivative. The reaction was supported by air and microwave irradiation. The presence of nitrate as counter anion in the protic ionic liquids was essential for the reaction.

Review

June 5, 2018

Iminiumsalz-Strukturen bei der durch Pyridoxalphosphat (Vitamin B₆) katalysierten Bildung von Aromastoffen und Fehlaromen im Wein

Nikolaus Müller

Page range: 521-533

Abstract

Enzymes that use pyridoxal phosphate (PLP, Vitamin B 6 ) as cofactor constitute a ubiquitous class of biocatalysts. A variety of PLP-dependant enzymes mainly involved in biochemical pathways concerning amino acid metabolism are found in all forms of life. These enzymes also play an important role in wine production, as well in grape growing as in enological processes. The formation of pleasant aroma compounds often runs with participation of pyridoxal-dependant enzymes. But these are also brought into context with the formation of off-odors, especially from sulfur compounds (i.e. sulfur containing amino acids cysteine, methionine). The versatility of PLP-dependant bioreactions arises from its ability to covalently bind the substrate and then to function as an electrophilic catalyst, thereby stabilizing different types of carbanionic reaction intermediates, containing iminium salt structures. This article summarizes the influence of PLP on sensorically important aroma compounds in wine growing and wine processing.

About this journal

Objective
Zeitschrift fuer Naturforschung B (ZNB) publishes novel research in all areas of inorganic chemistry, organic chemistry, and analytical chemistry. In particular, the journal focuses on solid state chemistry, coordination chemistry, main group element chemistry, synthetic organic chemistry, natural product chemistry and, to a lesser extent, on analytical chemistry. For more than 65 years Zeitschrift fuer Naturforschung B has been open to contributions from all fields of experimental and theoretical chemistry. Zeitschrift fuer Naturforschung B publishes 12 issues per volume/year. Sometimes double issues occur.

Topics

Solid state chemistry
Coordination chemistry
Main group element chemistry
Organic chemistry
Natural product chemistry

Article formats
Original (full) papers, research notes and preliminary communications, reports on specific research topics of current interest (reviews)

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Volume 73 Issue 7 - Special Issue: Iminium Salts and Imines

Issue of Zeitschrift für Naturforschung B

Frontmatter

In this Issue

The role of iminium salts, imines and related compounds in chemistry

A simple route to 2-aryl-substituted naphtho[2,1-e][1,2,4]triazinium and naphtho[2,1-e][1,2,3,4]tetrazinium salts from 1-arylazo-substituted 2-naphthylamines

Abstract

Orthoamide und Iminiumsalze, XCII. Synthese und Reaktionen von Orthoamiden aus ethinylierten Terpenderivatena

Abstract

Orthoamide und Iminiumsalze, XCIII. Darstellung und Umsetzungen eines vinylogen Orthoamid-Derivats der Kohlensäure mit CH2-aciden Verbindungena

Abstract

Synthesis of functionalized pyrazole derivatives by regioselective [3+2] cycloadditions of N-Boc-α-amino acid-derived ynones

Abstract

Chemistry and spectroscopy of cross-conjugated and pseudo-cross-conjugated quinolinium-ethynyl-benzoate mesomeric betaines

Abstract

Integrating the fluorene substructure into azaacenes: syntheses of novel fluorophores

Abstract

Thermal metal-free [2+2] cycloaddition of acetylenedicarboxylates to polysubstituted butadienes

Abstract

Protic ionic liquids as catalysts for a three-component coupling/hydroarylation/dehydrogenation tandem reaction

Abstract

Iminiumsalz-Strukturen bei der durch Pyridoxalphosphat (Vitamin B6) katalysierten Bildung von Aromastoffen und Fehlaromen im Wein

Abstract

Orthoamide und Iminiumsalze, XCII. Synthese und Reaktionen von Orthoamiden aus ethinylierten Terpenderivaten^a

Orthoamide und Iminiumsalze, XCIII. Darstellung und Umsetzungen eines vinylogen Orthoamid-Derivats der Kohlensäure mit CH₂-aciden Verbindungen^a

Iminiumsalz-Strukturen bei der durch Pyridoxalphosphat (Vitamin B₆) katalysierten Bildung von Aromastoffen und Fehlaromen im Wein