4-Alkyl-substituted tetrazole 1-oxides

Alkyl-substituted tetrazole 1-oxides 560 have been prepared by alkylation of the corresponding 1-hydroxytetrazole 555 with methylvinyl ketone to give a mixture of N-oxide 560 and the O-alkylated isomer 556 (1989BAU1488). Methylation of the A/-hyd roxytetrazole 555 with trimeth-yloxonium tetrafluoroborate afforded a mixture of N-oxide 560 (Alk=Me), an isomeric N-oxide of unknown structure, and the 1-methoxytetrazole 556 (Aik=Me) (1984BAU142) (Scheme 171). 

The 2-substituted tetrazole 1-oxides 550 were prepared from the corresponding hydroxytetrazoles 549 by methylation with trimethyloxonium tetrafluoroborate in CH2C12 at 20°C (1984BAU142) or by benzoylation of 1-hydroxytetrazole 549 (1913G71) (Scheme 165). Since N-alkylation and... 

Preparative methods and chemical properties of tetrazole-5-thiones (tetrazole-5-thiols) have been summarized in a review <2004RJ0447>. The most significant results in this field were obtained in the last decade while studying the alkylation of tetrazole-5-ylthiones (tetrazole-5-ylthiols), and the oxidation of 1-substituted 5-alkylsulfatetrazoles to the corresponding sulfinyl and sulfonyl derivatives. Special attention should be paid to the Kocienski-modified Julia olefination based on the application of 5-alkylsulfonyltetrazoles to the activation of chemical reactions. 

Pyridine A-oxides were converted to tetrazolo[l,5-a]pyridines 172 by heating in the presence sulfonyl or phosphoryl azides and pyridine in the absence of solvent <06JOC9540>. 3-R-5-Trinitromethyltetrazolo[l,5-a]-l,3,5-triazin-7-ones 173 have been prepared from the alkylation of 5-trinitromethyltetrazolo[l,5-a]-l,3,5-triazin-7-one silver salt with different alkylation agents <06CHE417>. The use of 2-fluorophenylisocyanide in the combinatorial Ugi-tetrazole reaction followed by a nucleophilic aromatic substitution afforded tricylic tetrazolo[l,5-a]quinoxaline 174 in good yields and with high diversity <06TL2041>. 

Other intramolecular conversions show the formation of tetrazolo[l,5-a]pyridines through the conversion of pyridine A -oxides into the corresponding 2-azidopyridines. These azides exist in equilibrium with the tetrazoles, resulting from the cycloaddition of the azide with the pyridine ring. The ratio of the equilibrium is dependent on the substitution of the heterocycle however the tetrazole usually dominates the azide species and can be converted into several other derivatives via hydrogenation, alkylation or arylation. ... 

Sulfoxides are oxidized to sulfoximides by HN3 in the presence of H2SO4 [1, 19]. The nucleophilic substitution of chloride by azide is accelerated, when the solution of HN3 and alkyl halide is allowed to react in a column filled with acidic AI2O3 [20]. The exchange of halide substituents of arenes by azide requires activating groups in other positions of the aromatic system. Pyridine derivatives frequently yield tetrazoles [8]. Aromatic C-nitroso compounds and twice the molar quantity of HN3 form the aromatic azide, N2, and H2O... 

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