O-Diazo oxides

Treatment of 2-diazophenols ( o-diazoquinones , o-diazo oxides ) with diazomethane at —10°C gives the 2//-tautomers l.52... 

A double cycloaddition is encountered in the reaction of o-diazo oxides and dimethyl-or diphenylketene. The first step is an addition of the ketene to the diazo oxide to give 325,... 

Recently from a comparison of the infra-red absorption spectrum of this compound with that of o-benzoquinone Glowiak [10] came to the conclusion that dinitro-benzenediazo-oxide has a quinonoid structure. Both substances show the presence of the strong absorption band of the carbonyl group 1666 cm-1 for dinitrobenzene-diazo-oxide and 1680 cm-1 for o-benzoquinone. In addition dinitrobenzenediazo-oxide gives a band with a frequency of 2190 cm-1, characteristic of a double bond between nitrogen atoms. (Some derivatives of this compound may also have the diazo structure (Ha), which is discussed later on.)... 

Replacement of the diazo group by hydrogen has been reported for a number of diazo oxides. For example, the diazo oxide from 2-nitro-4-aminophenol yields o-nitrophenol in 53% yield,42 - 43 and that from 1-amino-2-hydroxy-6-bromonaphthalene-4-sulfonic acid gives XV in approximately 50% yield.44... 

Certain nuclear substituents ortho to a newly formed diazonium group may interact to form a cyclic structure with or without retention of the nitrogen atoms. Such is the case in the diazotization of o-phenylene-diamine in aqueous solution, the product being 1,2,3-benzotriazole (81%). If the ortho substituent is an activated methyl group, an indazole is formed. Hydroxyl groups ortho or para to the diazonium group may interact to form internal condensation products called diazo oxides. These compounds may also form in the reaction of halo- and nitro-substituted aminophenols. 

Han and Weinreb [26] have attempted to develop a non-electrochemical approach towards a-oxidation of sulfonamides based upon the earlier work of Pines et al. [27]. The strategy here was to expose an o-diazo arylsulfon-... 

Startg. diazo oxide added portionwise during 10 min. to refluxing 30%-HBr-acetic acid, and the product isolated when gas evolution has ceased -> o-bromophenol deriv. (Y 82%) refluxed 5 min. with triphenylphosphine in nitromethane S-tert-butyl-5-hydroxy-4a-azoniaanthracene bromide (Y 98%). - This is part of a 4-step sequence to remove one hydroxyl from a pyrocatechol grouping. F. e. s. D. L. Fields and J. B. Miller, J. Heterocyclic Chem. 7, 91 (1970). 

Without additional reagents Diazo oxides from o-nitronitramines... 

Reactions of diazo compounds with nickel carbonyl s. 16, 847 Nickel sulfatejpotassium cyanide o-Hydroxynitriles from diazo oxides... 

Dioxole ring from 2 diazo oxide molecules O... 

Nickel sulfate potassium cyanide o-Hydroxynitriles from diazo oxides... 

The methylated carbenes lb-d are easily generated in argon matrices by photolysis of the corresponding diazo compounds.24 The IR and UV/vis spectra are very similar to that of la. In addition, the carbenes were chemically characterized by their reaction with molecular oxygen to give the corresponding quinone O-oxides 7b-d. 

During the oxidative copperizing process, an o-hydroxyazo compound reacts with a copper(II) salt in the presence of hydrogen peroxide. Both methods broaden the scope of metal complexation reactions by extending the selection of suitable diazo components [8,9]. 

When benzyne is generated by aprotic diazotization of anthranilic acid in boiling 1,2-dimethoxyethane in the presence of substituted benzene-2-diazo 1-oxides (o-quinonediazides), dibenzofurans are obtained in moderate yields (Scheme 64). ... 

Oxathiane 2-oxides aie fonned by the oxidative ring expansion of 2-alkylthio-2-benzylthiolane 1-oxides brought about by [bis(trifluoroacetoxy)iodo]benzene. That the reaction is only successful with the (lR )-diastereoisomeis is attributed to chelation between the nucleophilic S and O atoms and the hypervalent iodine <99EJ0943>. A diazo-mediated thiolane ring expansion is the key step in a synthesis of the acenaphtho-[U-b][l,4]oxathiine system <99JCS(P2)755>. 

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