Über den Mechanismus der nucleophilen Substitutionen an Bischlornitrosoverbindungen und α‐Chloroximen

Pritzkow, W.; Schaefer, H. J.; Pabst, Peter; Ebenroth, Axel; Beger, J.

doi:10.1002/prac.19650290302

Cited by 46 publications

(18 citation statements)

References 15 publications

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“…The postulation of this compound as an intermediate in the reaction provides a basis for the rationalization of the retention of configuratioil obtained in the overall reaction. Indeed, recently, Collin and Pritzkow (7,8) have shown several dimeric nitroso-chloro adducts of olefins to undergo nucleopl~ilic substitution by way of highly reactive conjugated nitroso-olefins to give a-substituted oximes. It was expected then, that the intermediate 2 would be strongly electrophilic especially in view of its enolic ether structure and readily undergo reaction with a wide variety of nucleophiles.…”

Section: -Acetyl-2-deoxy-2-nitroso-a-d-glucopyranosylmentioning

confidence: 99%

Synthesis of 3,4,6-Tri-O-acetyl-2-oximino-α-D-hexopyranosides

Lemieux¹,

Nagabhushan²,

Gunner³

1968

Can. J. Chem.

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The reaction of the dimeric nitrosyl chloride adducts of tri-0-acetyl-D-glucal and tri-0-acetyl-Dgalactal with alcohols and phenols in dimethylformamide at room temperature provides the corresponding tri-0-acetyl-2-oximino-a-D-hexopyranoside in good t o excellent yields. The condensation can also be carried out in tetrahydrofuran in the presence of pyridine or simply in refluxing methylene chloride for the simple alkyl alcohols. The stereospecificity of the reaction is extreme; only products of one configuration for both glycosidic linkage and the oximino group were detected. This result is rationalized on the basis of a cis-configuration for a tri-0-acetyl-2-nitroso-D-glycal intermediate in the H1 half-chair conformation. The introduction of methyl groups on the carbon of the methoxy group of methyl a-D-glucopyranosides causes a progressive deshielding of the anomeric proton. The data indicate that isopropyl a-D-glycopyranosides avoid the orientation for the aglycon which has the anomeric hydrogen projecting between the two methyl groups of the aglycon. Methyl tri-0-acetyl-6-0-(tri-0-acetyl-2-oximino-~-~-ara6ir~o-hexopyranosyl)-~-~-gucopyranoside was prepared in 70% yield to illustrate the use of the method for the preparation of an a-linked disaccharide.

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Section: -Acetyl-2-deoxy-2-nitroso-a-d-glucopyranosylmentioning

confidence: 99%

Synthesis of 3,4,6-Tri-O-acetyl-2-oximino-α-D-hexopyranosides

Lemieux¹,

Nagabhushan²,

Gunner³

1968

Can. J. Chem.

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“…However, a similar irradiation of anti-dimer 6 in a solution saturated with a commercial nitric oxide resulted in the recovery of the starting material 6 nearly quantitatively. The anti-dimer of trans-1-nitroso-2-chlorocyclohexane (9) was prepared by addition of nitrosyl chloride to cyclohexene (19)(20)(21). On irradiation of a benzene solution of the antidimer 9 under nitrogen, a white crystalline precipitate formed on the surface of the reaction vessel.…”

Section: Photodecompositionmentioning

confidence: 99%

Photoreactions of Nitroso Compounds in Solution. XXIV. Photooxidation and Photodecomposition of C-Nitroso Compounds

Chow¹,

Tam²,

Pillay³

1973

Can. J. Chem.

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Irradiation of the anti-dimers of C-nitroso compounds under nitrogen caused dissociation to the corresponding C-nitroso monomer which underwent photodisproportionation. tautomerization, and dimerization. Similar irradiation underhoxygen led principally to nitrate and nitrc~ compound formation. The disproportionation of N-(4-nitrosohexyl)acetamide was shown to occur by photodissociation of the C-nitroso monomer to the alkyl radical and nitric oxide. Under an oxygen atmosphere, those C-nitroso compounds which could undergo facile photodissociation were quickly oxidized to nitrates. As a result, mixtures of the corresponding cis-and trans-C-nitrates were obtained from the nnti-dimer of trans-l-nitroso-2-chlorocyclohexane. The anti-dimer of trans-I-nitroso-2-piperidinocyclohexane was photolytically tautomerized to the corresponding oxime under nitrogen and was oxidized chiefly to the C-nitro compound under oxygen; the two processes obviously share a common intermediate. Mechanisms for these photoprocesses are suggested.L'irradiation dans une atmosphere d'azote des dimeres-anti de composCs C-nitroso a provoquC la dissociation de ceux-ci pour donner le monomere C-nitroso correspondant lequel a subi une photodismutation, une tautomerisationet une dimkrisation. Une irradiation similairedans uneatmosphbre d'oxygeneaconduit principalement a la formation des produits nitrate et nitro. La dismutation de la N-(nitroso-4 hexyl) acCtamide se produit par photodissociation du monomere C-nitroso en radical alcoyle et en oxyde nitrique tel qu'il a CtC demontrt. Sous une atmosphere d'oxygene, ces composes C-nitroso qui peuvent subir une photodissociation facile ont CtC tres rapidement oxydCs en nitrates. Par suite, i partir du dimbre-crnti du trnns nitroso-l chloro-2 cyclohexane on a pu obtenir un mtlange des C-nitrates cis et anti correspondants. Le dimereonti du trans nitroso-1 piperidino-2cyclohexanea CtC tautomCrise photolytiquement pourdonner I'oxyme correspondant sous azote e t a CtC oxydC surtout en compose C-nitro sous oxygene; ces deux processus doivent necessairement possCder un intermkdiaire commun. Par suite, on suggere des mecanismes pour ces procCdes photochimiques.[Traduit par le journal]Can.

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“…In the presence of silver carbonate no a-acyloxy-azoxy compound similar to 5-7 (Scheme 7) could be detected; 50% of starting material was recovered. 12 was made by adding nitrosyl chloride to isobutene in the usual manner [8]. Compound 12 reacted with acid chlorides to give the trichloroazoxy compound 13 in 65-74% yield.…”

Section: Methodsmentioning

confidence: 99%

The Reaction of Nitrosoalkane Dimers with Acid Halides

Ribi

White

1975

Helvetica Chimica Acta

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Szcmmuvy. Nitrosoalkane dimers react with acid halides to yield a-halogeno-azoxy compounds with the substituent a to the oxygen-bearing nitrogen. In the presence of silver carbonate, the corresponding a-acyloxy-azoxy compounds are formed.The reaction of N-isobutyl-N-nitroso-hydroxylamine salts with 3,5-dinitrob2nzoyl chloride yields, among other products, 1-(3,5-dinitrobenzoyloxy)-1,1'-NNOazoxyisobutane (6) [l]. The known decomposition of nitrosohydroxylamines to nitrosoalkans dimsrs [2] suggests that compound 6 may have originated from an acylation of nitrosoisobutane dirner. In fact, the latter reaction does yield compound 6; a characterization of the products from such acylation of nitrosoalkane dimers is the subject of this paper.Reactions. -tram-1-Nitrosoisobutane dimer (2) [3-51, the structure of which has been proven by X-ray [6] diffraction techniques, was obtained by the oxidation of isobutylamine with m-chloroperbenzoic acid as described by Baldwilt et al. [7]. The nitroso dimer 2 reacted under very mild conditions, +20" over a period of 2 to 16 hours, with acid halides to give u-halogeno-azoxy compounds 3 and 4 in 65% and 41% yields (Schwze 1 ) . Methylene chloride, tetrahydrofuran and acetonitrile were useful solvents for this reaction, whereas no reaction occurred in toluene. Our reaction conditions were different from those of Collir, et al. [4], who treated nitrosoisobutane dimer 2 and related compounds with acetyl chloride in diethyl ether saturated with dry hydrogen chloride, and isolated the acylhydrazone hydrochloride 9 (presumably formed via 5) from 2.

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Über den Mechanismus der nucleophilen Substitutionen an Bischlornitrosoverbindungen und α‐Chloroximen

Cited by 46 publications

References 15 publications

Synthesis of 3,4,6-Tri-O-acetyl-2-oximino-α-D-hexopyranosides

Synthesis of 3,4,6-Tri-O-acetyl-2-oximino-α-D-hexopyranosides

Photoreactions of Nitroso Compounds in Solution. XXIV. Photooxidation and Photodecomposition of C-Nitroso Compounds

The Reaction of Nitrosoalkane Dimers with Acid Halides

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