Tetrazenes synthesis

Hoffmann etal. [26] suggested the structural formula (la) for tetrazene, i.e. l-guanyl-4-nitrosoaminoguanyltetrazene. The correctness of this formula was later questioned by Patinkin, Horwitz and Lieber [27]. The synthesis of tetrazene by the action of tetrazolediazonium hydroxide (II) on aminoguanidine salts (III) at 0°C, suggested that tetrazene has the structure of l-(5-tetrazolyl)-4-guanyltetrazene hydrate (I) ... 

The formation of guanyl azide (IV) at the first stage may account for the formation of tetrazene by the action of nitrous acid on aminoguanidine, i.e. by Hoffmann synthesis. 

Many attempts were made to synthesize the diazaazulene derivative 4,7-diphenyl-5,6-diazaazulene 34. A directed synthesis of diazaazulene 34 by [6+4] cycloaddition of fulvenes with 1,2,4,5-tetrazenes when attempted with 2-cyclopenta-dienyliden-l,3-dioxolane led to the formation of cyclopcnta[z/ pyridazines via a [4+2] cycloaddition pathway <2001TH1>. 

Methyl-5-(methylamino)-1 //-tctrazolc (401 R = CH3) was used as initial reagent in the synthesis of l,4-bis-[l-methyltetrazol-5-yl]-l,4-dimethyl-2-tetrazene 47, a formal hexamer of diazomethane. The synthetic pathway presumably involves intermediate formation of the corresponding nitrosotetrazole 402 and hydrazinotetrazole 405 (Scheme 48) <2004MI325>. 

The reaction between [Ir(Cl)(CO)(PPh3)2] and diazonium ions in the presence of ethanol or propan-2-ol affords the o-metallated diazene (112)276 and the iridium(III) tetrazene complex (113).277 A mechanism for the synthesis of (113) has been presented.278... 

The tetrazene syntheses [Eq. (35) and path (a), Eq. (37)] develop according to the general scheme IW + NN - NNNN. One possible synthesis of Group IV derivatives of tetrazene according to scheme N + NNN - NNNN consists of [2 + 3]-cycloaddition of azides to sila- or germaketimines (stannaketimines are still not known) to form cyclic tetrazenes 34 (sila- or germatetrazolines) [Eq. (38)] (Preparation... 

Treatment of acylhydrazines with diazonium salts gives rise to tetrazenes (199) which can be readily dehydrated with base to give 1,5-disubstituted tetrazoles (Scheme 33). The reaction is also effective with 1,2-diacylhydrazines since one of the acyl groups is cleaved during the dehydrative cyclization, which may be conveniently carried out in situ without isolation of the tetrazene. This reaction can be useful for the synthesis of 1-aryltetrazoles using 1,2-diformylhydrazine as substrate (B-67MI41300). Mesoionic tetrazolium 5-oxides (8a) are obtained on treatment of bis(alkylsulfonyl)methanes with diazonium salts. Hydra-zones of type (200) are also obtained from these reactions and the tetrazenes... 

Aliphatic amines are mainly converted to a-substituted products [99,100], whereby especially the a-methoxylation leads to valuable reagents for synthesis. The intermediate iminium salts can be directly trapped by silyl enol ethers to form Mannich bases [108]. If the a-position is blocked or steric conditions favor it, N,N coupling to hydrazo or azo compounds occurs (Table 5, numbers 17-19). 1,1-Disubstituted hydrazines are dimerized to tetrazenes in fair to excellent yields (Table 5, numbers 20-24). The intermediate diaze-nium ions can attack enolizable carbonyl compounds to form aza-Mannich bases [109]. Arylazonaphthols undergo anodic oxidation, producing radical cations. These couple to biphenylbisazo compounds (up to 34%) or can be trapped by anisidine to form azodiphe-nylamines (up to 74%) [110a]. 

The cis-cyclic tetrazene was formed in 5 percent yield by basic oxidation of the precursor dihydrazine (R Me) with sodium hypochlorite. A general synthesis of tetrazenes of this type was worked out by Seebach and co-workers (, 58, ). The... 

Oxidation of 1 (doubly enriched) at -78°C afforded a deep purple solution which gave rise to a N spectrum consisting of four doublets at 321.4 ppm (J = 15.5 Hz), 917.0 ppm (J 15.5 Hz), 419.5 ppm (J = 6.4 Hz), and 164.6 ppm (J = 6.4 Hz). The last two were assigned to tetrazene by independent synthesis, and specific resonance assignments were confirmed by spectral determination of and derived from labeled only at N2 The remarkably deshielded N2 represents the most highly deshielded neutral nitrogen known (49). Interestingly, Nj in both and displayed maximum NOE s. 

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