Diazotates 3-Dicarbonyl compounds

Diazocarbonyl compounds can be prepared on insoluble supports by diazo group transfer with sulfonyl azides or by diazotization of primary amines. Diazo group transfer from sulfonyl azides to 1,3-dicarbonyl compounds proceeds on cross-linked polystyrene as smoothly as in solution (Table 10.19). When 3-keto esters or amides are... 

The diaminobenzenes (phenylenediamines) are prepared by reduction of 1,3-dinitrobenzene and 2- and 4-nitroanilines. o-Phenylenediamine is of value in the synthesis of a range of nitrogen heterocycles. Thus reaction with organic acids produces benzimidazoles (8). With 1,2-dicarbonyl compounds, quinoxalines (9) are produced. Treatment with nitrous acid results in diazotization of one amino group followed by immediate cyclization to give benzotriazole (10). 

The parent ring system (53) was prepared by diazotization of 2-hydrazinopyrimidine (57JAP570777). Alkyl derivatives of (53) have been synthesized by the condensation of /3-dicarbonyl compounds with 5-aminotetrazole (79JCS(P1)3085). For example, treatment of 5-aminotetrazole with pentane-2,4-dione gave 5,7-dimethyltetrazolo[l,5-a]pyrimidine (Scheme 72) (65JOC826). 

Diazotization Synthesis of arenediazonium salts from benzenamines (anilines) using cold nitrous acid. t-Dicarbonyl compound A useful intermediate bearing two carbonyl groups adjacent to the same... 

The direct diazo transfer from sulfonyl azides to methyl ketones is usually not a practicable process, with the exception of the a-diazotization of ketones with 2,4,6-triisopropylbenzenesulfonyl azide under phase-transfer conditions. However, diazomethyl ketones amenable to the Arndt-Eistert reaction can be easily prepared in two steps by a formylation-deformylation diazo-transfer sequence (Regitz procedure ). A related practical method advantageously applies the detrifluoroacetylation of a-trifluoroacetyl ketones tScheme 3 a). The preparation of 2-diazo-1,3-dicarbonyl compounds is commonly best performed with p-toluenesulfonyl azide (TsNg) as the diazo-transfer reagent tScheme 3.9h). > An issue... 

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