Tetrazole metallation

Metalation of the ring carbon is possible with 1,2,3-triazole and tetrazole. Metalation of alkyl substituents in the a-position of the ring succeeds with 1,2,5-oxadiazole, 1,2,4-thiadiazole, benzotriazole and tetrazole. 

Tetraphosphine ligands, 995 Tetrapyridyls metal complexes, 91 geometry, 91 Tetrapyrroles metal complexes, 79 T etraselenoether metal complexes, 666 Tetrasulfur tetranitride metal complexes, 799 Tetrathiolane, bis(imino)-metal complexes, 591 Tetrathiooxalic acid metal complexes, 585, 606 Tetrathiosquaric acid metal complexes, 606 Tetrazole, 2-methyl-metal complexes, 77 Tetrazole, pentamethyl-metal complexes, 77 Tetrazoles metal complexes, 76 pK,ll... 

Despite the weak basicity of isoxazoles, complexes of the parent methyl and phenyl derivatives with numerous metal ions such as copper, zinc, cobalt, etc. have been described (79AHC(25) 147). Many transition metal cations form complexes with Imidazoles the coordination number is four to six (70AHC(12)103). The chemistry of pyrazole complexes has been especially well studied and coordination compounds are known with thlazoles and 1,2,4-triazoles. Tetrazole anions also form good ligands for heavy metals (77AHC(21)323). 

A number of studies have been reported concerning azide-isocyanide condensations to give tetrazoles. Early work by Beck and co-workers 18, 19) describes the addition of various isocyanides to metal azido species [Au(N3)4]", [Au(N3)2]", Au(PPh3)N3, and M(PPh3)2(N3)2, M = Pd, Pt, Hg. The products are carbon-bonded tetrazolato-metal complexes. It is not known whether metal isocyanide complexes are intermediates in these reactions. More recently inverse reactions with azide ion addition to metal isocyanide complexes were carried out, with similar results. From... 

See Other A-METAL DERIVATIVES, SILVER COMPOUNDS, TETRAZOLES... 

See entry nitramine- metal complexes See other a-nitro compounds, tetrazoles... 

See entry METAL azotf.tr azot. ides See other tetrazoles... 

See related metal azotetrazolides See other iv-oxides, tetrazoles... 

Major advancements in the chemistry of pyrazoles, imidazoles, triazoles, tetrazoles, and related fused heterocyclic derivatives continued in 2000. Solid-phase combinatorial chemistry of pyrazoles and benzimidazoles has been particularly active. Synthetic routes to all areas continue to be pursued vigorously with improvements and applications. Notably, metal-promoted and cross-coupling reactions of all classes seemed to be a dominant theme in 2000. Applications of pyrazole-, imidazole-, and 1,2,3-benzotriazole-containing reagents to a wide array of synthetic applications remained active. 

We are investigating the template formation of 2-D and 3-D metal-di-cyanamide anionic networks, for instance of type Mn(dca)3, by use of [M(N,N)3]n+ cations such as [M(2,2 -bipy)3]2+. A hexagonal sheet network was formed in [Fen(2,2 -bipy)3][Fen(dca)3]2 in which the cations fitted beautifully within the hexagonal windows. The cation remained LS between 4-300 K [66], Attempts to make the Con(2,2 -bipy)32+ analogue unfortunately led to dissociation of dca and bipy and formation of a zig-zag chain structure in the weakly-coupled HS complex [Con(dca)2(2,2 -bipy)2]n. The complex [Fen(propyl-tetrazole)6]2+, which has a very sharp SCO transition [42], unfortunately did not yield a network product. 

Method a. The most frequent approach is the treatment of cr-halogenoazines by metal azides. Tetrazoles that have been synthesized recently via this methodology are compiled in Table 6. Inspection of these data reveals that all these transformations proceed in good yields. 

Qu6guiner and co-workers found that some diazinylazides suitable for formation of fused tetrazoles can be obtained via metallation of the diazine ring as shown in Scheme 19 <1996S838>. 

We first consider the Demko and Sharpless article (2001) on the synthesis of substituted tetrazoles from nitriles in water (excerpt 5D). This excerpt is particularly useful because it illustrates several types of content that authors typically discuss in synthesis papers. The authors begin by proposing two possible mechanisms for the tetrazole reaction, a two-step mechanism and a concerted mechanism. The mechanisms are presented in a scheme (Scheme 1). In the accompanying text, the authors cite evidence for both mechanisms, highlight salient features of the mechanisms, mention the results of kinetic studies, and point out that the role of zinc metal is as yet unclear. 

Table 1 Metals complexed with substituted tetrazoles.

Metal salts of 5-substituted tetrazoles (83) undergo ready alkylation on heating with alkyl halides in a wide range of solvents (Equation (9)). The products are mixtures of 5-substituted-1 A- and 2N-... 

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