Published by De Gruyter

Volume 71 Issue 6 - Special issue: Iminium Salts and Imines

Issue of Zeitschrift für Naturforschung B

Contents
Journal Overview

Publicly Available June 3, 2016

Frontmatter

Page range: i-iii

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Publicly Available June 3, 2016

Preface

Publicly Available May 31, 2016

Chemistry of the iminium and imine functional groups

Gerhard Maas

Page range: 621-621

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Publicly Available April 1, 2016

Transformations of β-aryl-N-Cbz-α,β-didehydro-α-amino esters with hydrazine hydrate

Miha Drev, Uroš Grošelj, Jurij Svete

Page range: 623-631

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Abstract

Cyclizations of Cbz-protected α , β -didehydro- β -arylalanine esters 1 with excess hydrazine hydrate afforded mixtures of the expected 3-pyrazolidinones 2 and the unexpected 1-amino-5-benzylidenehydantoins 6 and N -Cbz- β -arylalanine hydrazides 7 . Presumably, the pyrazolidinones 2 and hydantoins 6 are formed as primary products via competitive 1,2- and 1,4-addition of hydrazine hydrate followed by cyclization, whereas β -arylalanine hydrazides 7 are formed as secondary products via reductive cleavage of the C(5)–N(1) bond in pyrazolidinones 2 . The overall selectivity depends on the reaction time and on the β -substituent in the starting dehydroalanine ester 1 .

Publicly Available April 12, 2016

A short synthesis of pyridines from deprotonated α-aminonitriles by an alkylation/RCM sequence

Carina Weber, Marco M. Nebe, Lukas P.V. Kaluza, Till Opatz

Page range: 633-641

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Abstract

α -Aminonitriles can serve as versatile key precursors for the synthesis of nitrogen containing heterocycles. After unsuccessful trials involving the [1,2]-Stevens rearrangement of nitrile-stabilized ammonium ylides, we herein report a simple three-step synthesis of substituted pyridines based on an alkylation/ring-closing metathesis/aromatization sequence.

Publicly Available April 1, 2016

Palladium complexes of anionic N-heterocyclic carbenes derived from sydnones in catalysis

Ana-Luiza Lücke, Sascha Wiechmann, Tyll Freese, Zong Guan, Andreas Schmidt

Page range: 643-650

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Abstract

The anion of N -phenylsydnone, which can be generated on treatment of N -phenylsydnone with cyanomethyllithium without decomposition, can be represented as tripolar zwitterionic and as anionic N-heterocyclic carbene resonance forms. Its palladium complex was prepared from 4-bromo-3-phenylsydnone and tetrakis(triphenylphosphine)palladium and proved to be active as catalyst in Suzuki-Miyaura reactions. Thus, 2,5-dibromo-3,4-dinitrothiophene was effectively converted into 2,5-diaryl-3,4-dinitrothiophenes with 1-naphthyl, (4-trifluoromethoxy)phenyl, [4-(methylsulfanyl)phenyl], and biphenyl-4-yl boronic acid. 3-(Phenanthren-9-yl)quinoline was prepared by Suzuki-Miyaura reaction starting from 3-bromoquinoline. 1-Chloro-2,4-dinitrobenzene cross-coupled with phenyl boronic acid, 1-naphthyl boronic acid, 9-phenanthryl boronic acid. 4-Bromobenzylic alcohol gave (4-isopropylphenyl)methanol on sydnone-palladium complex-catalyzed reaction with isopropyl boronic acid.

Publicly Available May 11, 2016

Synthesis and characterisation of long wavelength-absorbing donor/acceptor-substituted methine dyes

Christoph Heichert, Horst Hartmann

Page range: 651-658

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Abstract

By the reaction of aromatic or heteroaromatic formyl compounds or their corresponding iminium salts with active methylene compounds a series of new methine dyes with long-wavelength absorption in the near-infrared spectral range were prepared.

Publicly Available April 20, 2016

Selective di- and monochlorination of pyridazine-annelated bis(imidazolium) salts

Benjamin Raible, Doris Kunz

Page range: 659-666

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Abstract

A synthetic route for the selective di- and monochlorination of pyridazine annelated bis(imidazolium) salts at the formamidinium moieties with trichloroisocyanuric acid (TCCA) is presented. Due to the steric hindrance, the molecular structure of the dichlorobis(imidazolium) salt shows a pronounced torsion from planarity as well as a deviation of the C–Cl bond vectors from the ideal bisecting line of the respective NCN angles such as to avoid each other. The monochlorinated bis(imidazolium) salt is free of steric hindrance and therefore shows less deviation from the parent bis(imidazolium) salt. In the presence of acetate the chloroimidazolium salt acts as a chlorination agent for acetate leading to formation of acetyl chloride and the respective urea.

Publicly Available April 18, 2016

Synthesis and investigation of new cyclic haloamidinium salts

Eduard Rais, Ulrich Flörke, René Wilhelm

Page range: 667-676

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Abstract

The presented work describes the synthesis of new six- and seven-membered haloamidinium salts and their reaction with different metals. The isolated metal complexes were tested in a catalytic reaction. Two different synthetic routes were applied to prepare five different salts. Chloroamidinium salts were very water-sensitive in comparison to their corresponding bromoamidinium salts. Hence, the preparation of the less sensitive bromoamidinium salts was higher prioritized. The formed salts were converted with metal sources to N-heterocyclic carbene (NHC) metal complexes through an oxidative insertion into the C–X bond. This type of formation is less examined for the synthesis of extended NHC metal complexes. Pd(PPh 3 ) 4 and cobalt powder were applied as metal sources, whereby two palladium complexes were isolated, characterized, and their crystal and molecular structures determined. The palladium complexes were investigated in the Suzuki-Miyaura reaction and showed promising catalytic activity.

Publicly Available April 12, 2016

A simple synthesis of dimethyl 2-[(Z)-3-amino-1-oxo-1-(substituted)but-2-en-2-yl]fumarates: potential intermediates in the synthesis of polysubstituted five- and six-membered heterocycles

Rok Šinkovec, Uroš Grošelj, Benjamin Prek, Marta Počkaj, Sebastijan Ričko, Jurij Svete, Branko Stanovnik

Page range: 677-682

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Abstract

In this communication, a simple synthesis of dimethyl 2-[( Z )-3-amino-1-oxo-1-(substituted)but-2-en-2-yl]fumarates is described. Methyl ketones were transformed by treatment with N,N- dimethylacetamide dimethyl acetal (DMADMA) into 3-dimethylamino-1-(substituted)but-2-en-1-ones, followed by treatment with ammonium acetate into ( Z )-3-amino-1-(substituted)but-2-en-1-ones and addition to dimethyl acetylenedicarboxylate. These novel polysubstituted butadienes are potential intermediates for the metal-free preparation of polysubstituted five- and six-membered heterocycles.

Publicly Available April 7, 2016

2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidine as ligands in copper(II) and nickel(II) complexes

Sven Schröder, Wolfgang Frey, Gerhard Maas

Page range: 683-696

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Abstract

2-(1-Benzyl-1 H -1,2,3-triazol-4-yl)-imidazolines ( L1 and L2 / L2 ′), -1,3-oxazoline ( L3 ), -1,3-thiazoline ( L4 ) and -tetrahydropyrimidine ( L5 ) were prepared in one step from a 1,2,3-triazole-4-carboxamidinium tetraphenylborate and studied as novel ligands for copper(II) and nickel(II) ions. The solid-state structures of the following complexes were established: [Cu( L1 ) 2 ](OTf) 2 , [Cu L2L2 ′(OTf) 2 ] · 2H 2 O, [[Cu( L4 ) 2 (H 2 O) 2 ](OTf) 2 · [Cu( L4 ) 2 (OTf) 2 ], [Cu( L5 ) 2 (OTf) 2 ], Cu( L3 ) 2 Cl 2 ] · THF, [Ni( L1 ) 2 Cl 2 ].

Publicly Available April 6, 2016

Derivatives of the triaminoguanidinium ion, 4. O-Sulfonylation of N,N′,N″-tris(hydroxybenzylidenamino)guanidinium ions

Jan Szabo, Gerhard Maas

Page range: 697-703

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Abstract

All hydroxy groups of the N , N ′, N ″-tris(4-hydroxybenzylidenamino)guanidinium and N , N ′, N ″-tris(2,4-dihydroxybenzylidenamino)guanidinium ions could be sulfonylated in good yields to obtain three-fold or six-fold substituted and functionalized derivatives. The 2,4-dihydroxyphenyl containing precursors have been used to construct branched three-armed guanidinium derivatives bearing six dansyl or anthraquinone moieties.

Publicly Available April 21, 2016

Consecutive three- and four-component coupling-Bagley-Bohlmann-Rahtz syntheses of tri- and tetrasubstituted pyridines

Janis Dohe, Thomas J.J. Müller

Page range: 705-718

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Abstract

The concatenation of the modified Sonogashira alkynone synthesis and the Bagley-Bohlmann-Rahtz pyridine synthesis gives novel consecutive three- and four-component coupling-Bagley-Bohlmann-Rahtz (cBBR) syntheses of tri- and tetrasubstituted pyridines in a one-pot fashion. With these processes 15 differently substituted 3-ethoxycarbonyl 2-methylpyridines can be readily obtained in modest to moderate yields.

Publicly Available April 29, 2016

Orthoamide und Iminiumsalze, XCI. N,N′,N″-Peralkylierte Guanidiniumsalze – Ionische Flüssigkeiten als Hilfsmittel in der Elektronenmikroskopie

Georg Knobloch, Stefan Saur, Anja Rebecca Gentner, Stefan Tussetschläger, Thorsten Stein, Berthold Hader, Willi Kantlehner

Page range: 719-735

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Abstract

Polymeric organic materials, e.g. cellulose fibres or nylon 6 (perlon), as well as inorganic materials, e.g. ceramics, can be coated with liquid or solid guanidinium salts. The coated materials can be inspected by scanning electron microscopy (SEM). The contrast and brightness of the pictures depend on the heaviest atom present in the anions. The best brightness and contrast were obtained with N,N ′ ,N ″-peralkylated guanidinium tetraiodidobismutates(III), which were prepared for the first time together with other guanidinium chloridometallates (Sb, Pb, Bi). Biological samples (cell cultures) can also be investigated by SEM with the aid of the guanidinium tetrachloridobismutate 4b after simple sample preparation.

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 71 Issue 6 - Special issue: Iminium Salts and Imines

Issue of Zeitschrift für Naturforschung B

Frontmatter

In this Issue

Chemistry of the iminium and imine functional groups

Transformations of β-aryl-N-Cbz-α,β-didehydro-α-amino esters with hydrazine hydrate

Abstract

A short synthesis of pyridines from deprotonated α-aminonitriles by an alkylation/RCM sequence

Abstract

Palladium complexes of anionic N-heterocyclic carbenes derived from sydnones in catalysis

Abstract

Synthesis and characterisation of long wavelength-absorbing donor/acceptor-substituted methine dyes

Abstract

Selective di- and monochlorination of pyridazine-annelated bis(imidazolium) salts

Abstract

Synthesis and investigation of new cyclic haloamidinium salts

Abstract

A simple synthesis of dimethyl 2-[(Z)-3-amino-1-oxo-1-(substituted)but-2-en-2-yl]fumarates: potential intermediates in the synthesis of polysubstituted five- and six-membered heterocycles

Abstract

2-(1,2,3-Triazol-4-yl)-imidazoline, -oxazoline, -thiazoline and -tetrahydropyrimidine as ligands in copper(II) and nickel(II) complexes

Abstract

Derivatives of the triaminoguanidinium ion, 4. O-Sulfonylation of N,N′,N″-tris(hydroxybenzylidenamino)guanidinium ions

Abstract

Consecutive three- and four-component coupling-Bagley-Bohlmann-Rahtz syntheses of tri- and tetrasubstituted pyridines

Abstract

Orthoamide und Iminiumsalze, XCI. N,N′,N″-Peralkylierte Guanidiniumsalze – Ionische Flüssigkeiten als Hilfsmittel in der Elektronenmikroskopie

Abstract