Diazo-anhydrides

Primary amino groups attached to azole rings react normally with nitrous acid to give diazonium compounds via primary nitroso compounds. However, the azole series shows two special characteristics the primary nitroso compounds can be stable enough to be isolated, and diazo anhydrides are formed easily from azoles containing ring NH groups. 

Diazotization of aminoazoles with free cyclic NH groups can give diazo anhydrides which show many of the normal reactions of diazoniums (67AHC(8U). In the pyrazole series these diazo anhydrides are particularly stable. 

Bis[Dinitro-hydroxy-azo-quinone], called by v. Herz sym-Tetranitro-dioxy-diphenol-quinone-tetrazide, or Tetranitro-diresorcin-diazo-anhydride... 

Herz Dinitro-m-oxy-quinone-diazide, or Dinitro-resorcin-diazo-anhydride... 

P-Aminopyridones form diazo anhydrides (e.g. 729) (cf aminophenols) which on irradiation give pyrrolecarboxylic acids (731) via (730). 

The term diazohydroxide will be used to include the so-called diazo anhydrides. 

Nitrophthalic acid has usually been prepared by nitration of phthalic add or phthalic anhydride, followed by separation from the accompanying 3-nitrophthalic acid. It has also been prepared from 6-nitro-2-naphthol-4-sidfonic acid (obtained from the technical diazo-anhydride of 6-nitro-i-amino-2-naphthol-4-sulfonic acid). The present procedure is more convenient than any of the earlier methods. 

Cyclic carbonyl ylides, formed from diazo amides or diazo anhydrides through intramolecular carbene addition to the carbonyl group, react with the triple bond of a dipolarophile to produce bicyclic adducts. The latter undergo a retrodiene reaction, splitting off an alkyl isocyanate or carbon dioxide to give furan derivatives. 

Diazo anhydride 304 decomposes in the presence of a Pd(II) catalyst and acetylenic dipolarophiles affording, carbon dioxide and furans 305 (70-86%) (85CC190). 

Wolff, L. Diazo Anhydrides (1,2,3-Oxydiazoles or Diazo Oxides) and Diazo Ketones. Ann. 1913, 394, 23-59. 

Wolff, L. Diazo anhydride (1,2,3-oxydiazoles or dIazooxIdes) and diazo ketones. Liebigs Ann. Chem. 1912, 394, 23-108. 

Primary amino groups on imidazole react with nitrous acid to give diazonium salts by way of primary nitrosamines. These salts can sometimes be isolated and converted into stable diazo anhydrides if the imidazole has a free NH group. Reviews of diazoazole chemistry have appeared... 

The main methods available to prepare 1,3-oxathiolium salts and their mesoionic 4- and 5-olates are of this type and were covered in CHEC-I <84CHEC-I(6)749> but two important new methods have been described. The 2-amino-1,3-oxathiolium salts (208) can be obtained by desulfurization of the phenacyldithiocarbamates (207) with a silver, mercury, or copper salt (Equation (28)) <92JAP04364178>. The l,3-dioxolium-4-olates (210) have been generated from the a-diazo anhydrides... 

Mixed hiaryls. The synthesis of biaryls by the Gomberg-Bachmann reaction of aryidiazonium salts and arencs can be conducted to advantage under phase-transfer catalysis using potassium acetate to form a diazo anhydride. KOAc can be replaced by NaOH, KOH, or K2CO3, but with lower yields. 

Diazoacetic esters, 500, 501 Diazo anhydrides, 130 cr-Diazo ketones, 118-119, 271 Diazomethane, 500 Diazomethyltrimethylsilane, 188 DIBAL, 173... 

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