Aryliminodimagnesium Reagents Research Articles

ChemInform Abstract: Aryliminodimagnesium Reagents. Part 19. Effects of Miscellaneous Metal Halides on Oxidative Self-Coupling of the Reagent, and on Its Condensation with Nitrobenzene. A New Preparative Route to o,o′- Dihydroxyazobenzene.

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ChemInform Abstract: Aryliminodimagnesium Reagents. Part 20. Reactions of Aryliminodimagnesium (I) with Some N,N-Dimethylcarboxamides (II), (VI) and Benzonitriles (IV) Affording Various Types of Amidines. Correction of Previous Results on Formamidine Form

ChemInform Abstract: Aryliminodimagnesium Reagents. Part 20. Reactions of Aryliminodimagnesium (I) with Some N,N-Dimethylcarboxamides (II), (VI) and Benzonitriles (IV) Affording Various Types of Amidines. Correction of Previous Results on Formamidine Form

Aryliminodimagnesium Reagents. XIX. Effects of Miscellaneous Metal Halides on Oxidative Self-Coupling of the Reagent, and on Its Condensation with Nitrobenzene. A New Preparative Route to o,o′-Dihydroxyazobenzene

Abstract Fourteen metal halides (MXn) were each added to the solutions of aryliminodimagnesium (p-RC6H4N(MgBr)2, IDMg) in tetrahydrofuran, and the effect of MXn on relative yields of products was examined in the following three IDMg reactions: (A) oxidative coupling leading to symmetrical azobenzene, (B) condensation with nitrobenzene, and (C) condensation with o-hydroxy-substituted (o-HO) nitrobenzene. Reaction A was promoted by addition of CuCl2, and the yield of azoxybenzenes in reaction B was improved by addition of NiCl2 or CdCl2. Reaction C was similarly modified by addition of CdCl2 so as to improve the yield of o-HO-azoxybenzenes. Their acetyl derivatives underwent a facile photoinduced migration of azoxy oxygen and were successively hydrolyzed to afford bidentate chelating agents, o,o′-(HO)2-azobenzenes.

ChemInform Abstract: Aryliminodimagnesium Reagents. Part 26. Formation of o‐Hydroxyazoarenes by Condensation with o‐Hydroxynitroarenes. Favorable Role of o‐Hydroxyl Group in the Reaction.

AbstractHydroxy‐azoxyarenes such as (II) as well as hydroxy‐azoarenes such as (III) are formed by condensation of, e.g., the aryliminodimagnesium species (V) with o‐, m‐, and p‐hydroxynitrobenzenes (I); nuclear substitution takes place as a minor or a major pathway.

Aryliminodimagnesium Reagents. XVI. Formation of o-Hydroxyazoarenes by Condensation with o-Hydroxynitroarenes. Favorable Role of o-Hydroxyl Group in the Reaction

Abstract Hydroxy(HO)-azoxy- and -azoarenes were formed by condensation of ArN(MgBr)2 with o-, m-, and p-HO-nitrobenzenes; nuclear substitution took place as a minor or a major pathway. o-HO-azobenzene was obtained in sufficiently high yield. Relative yields of the products varied according to the position of HO group and reaction conditions. The yield variation was explained by the effects of relative efficiency of single electron transfer, σ-complexation, and cooperation of reagent molecules.

Azoxy- and Azoferrocenes, andN-(Ferrocenylarylmethylene)anilines Formed via Aryliminodimagnesium(IDMg) Procedure. Effect of Ferrocenyl Group on IDMg Reaction and Molecular Structures of Products

Some unsymmetrical azoxy- and azoferrocenes and N-(ferrocenylarylmethylene)anilines were obtained by the reactions of aryliminodimagnesium reagents (ArN(MgBr)2) with nitro- and aroylferrocenes. The types of products were same as those obtained in the similar reactions with nitrobenzenes and benzophenones. The different distribution of products arising from quite mild reactions was understood by the effect of bulky and electron-rich ferrocenyl group which retards the initial coordination and electron transfer processes, in comparison with that of phenyl group. The characteristic molecular structures of the new ferrocene compounds were studied by means of electronic absorption, 1H NMR, and X-ray crystallography. The results were summarized and discussed.

Aryliminodimagnesium Reagents. XII. The Distribution of Products in the Condensation with Nitrobenzothiazoles. Reduction of Electron-Donating Ability of Reagent by the Interaction with Thiazolyl Group

Abstract The 4-, 5-, 6-, and 7-nitro derivatives of benzothiazole condense with ArN(MgBr)2 giving unsym-azoxy and -azo products. The product distribution indicated the mild nature of the reaction, and could be explained in terms of a reduced electron-donating ability of the reagent due to an interaction with thiazolyl group.

Aryliminodimagnesium Reagents. XI. Two-Electron Oxidation of the Reagent Molecules in the Reaction with Some Oxidizing Agents and with Strongly Push-Pull Substituted α-Benzylideneacetophenones

Abstract The reactions of an aryliminodimagnesium reagent (ArN(MgBr)2) with four oxidizing agents ((i): I2, OsO4, C6H5IO2, I2O5) and four push-pull substituted α-benzylideneacetophenones(ii) were examined. In the reactions with (i), the maximum yield of sym-azobenzene was 50%. In the reactions with (ii), in addition to products formed via condensation and the typical radical processes, unexpected products formed via cleavages of C=C and Cβ–H bonds were observed. Summarizing these results, a pathway involving the formation of arylnitrene-like species via disproportionation of arylaminyl radicals (Ar\.{N}MgBr) has been proposed.

Aryliminodimagnesium Reagents. X. The Mild Reagent Derived from 2-Aminopyridine and Formation of Highly Reactive Azoxypyridines in the Reaction with Nitrobenzenes

Abstract The reaction of iminodimagnesium reagent derived from 2-amino-4-methylpyridine with nitrobenzenes was examined. The relative yields of the azoxypyridine formed via condensation and the azopyridines via deoxygenation and oxidative dimerization were explained in terms of weak electron-donating ability of the reagent and the strong electron-accepting ability of the azoxypyridine.

Aryliminodimagnesium Reagents. IX. The Reaction with Benzophenones. The Mechanism of Coordination and Electron Transfer Processes Distinct from That of Grignard Reaction

Abstract In the reaction of aryliminodimagnesium reagents(ArN(MgBr)2, Ar=C6H5, p-MeC6H4, and p-MeOC6H4) with some p-substituted benzophenones, the arylaminyl radicals(ArNMgBr) derived from the reagents were detected by ESR in low concentrations and identified by computer simulation. From comparison of all the itemized facts characteristic of the reaction with those of Grignard reaction of the same substrates, the mechanisms of initial coordination and electron transfer of the two reactions were distinguished.

Aryliminodimagnesium Reagents. VI. The Reactions with Conjugated Carbonyl Compounds. The Initial Coordination and the Electron-transfer in the Reactions of Organomagnesium Reagents

Abstract The reactions of aryliminodimagnesium reagents (ArN(MgBr)2) with benzylideneacetophenones, quinones, and benzils were examined. Among the product-distributions in the reactions with the enones and the α-diketones, some examples in which p-MeO-substituted substrates gave higher yields of condensation products were obtained. The results are in contrast with the product-distributions in the reaction of ArMgBr with Ar1COAr2 and that of ArN(MgBr)2 with Ar1NO2: p-Cl-Substituted substrates are advantageous for the formation of addition and/or condensation products. These reactions of the two organomagnesium reagents were classified into “coordination controlled” and “electron-transfer controlled” ones on the basis of the combination of electron-donating ability of reagents with the electron-accepting ability of substrates. The classification was illustrated also on the basis of the relative difference of the energy levels of HOMO’s and LUMO’s of the reactants.

Aryliminodimagnesium Reagents. IV. The Independent Preparation of Unsymmetrically Substituted Azoxyarene Isomers and Their Deoxygenation

Abstract By use of the condensation reaction of aryliminodimagnesium reagents (ArN(MgBr)2) with nitroarenes, six symmetrical and eight unsymmetrical azoxyarenes including four pairs of isomers were prepared in 40–80% yields. The deoxygenation reaction of the azoxyarenes by treating with five molar equivalents of p-MeOC6H4N(MgBr)2 at 55 °C in tetrahydrofuran was also studied, and the reactivity of deoxygenation was correlated to the shift of the electronic absorption maximum of azoxyarene.